The Theropod Database Blog

Agnolin and Novas's (2011) cheating for unenlagiine monophyly?

2012-01-17T16:02:00.000-08:00

Here's a quick example of the fun I find when checking matrices for my analysis. Agnolin and Novas (2011) took Hu et al.'s (2009) matrix and recoded some paravians, as well as adding three new characters to support unenlagiine monophyly- maxilla elongate, postantral wall extensive, teeth grooved. They got a result that's fairly unique in placing unenlagiines as avialans instead of dromaeosaurids. I'm adding the data into my matrix and notice the matrix has five new characters added instead of three, all of which are only present in Buitreraptor and Austroraptor. Well, except the last one, which is seemingly the third they list (grooved teeth) since its codings would suggest it is tooth-based (though wrongly coded for Garudimimus, ornithomimids and Confuciusornis) and present in Sinornithosaurus (and incorrectly in Compsognathus). As if two phantom characters weren't bad enough, the authors clearly didn't actually check if taxa had them, instead merely going through the matrix and marking anything with cranial material '00000'. This includes taxa which can't be coded for maxilla elongation or maxillary postantral wall elongation like Tanycolagreus, Coelurus, Mononykus, Falcarius, Alxasaurus, Protarchaeopteryx and Caenagnathus, and even some taxa with no cranial material like Archaeornithomimus and Anserimimus. Sure none of those taxa are close to unenlagiines so their coding really doesn't matter here, but it sets such a bad precident. Someone who didn't notice this could go through the matrix and see Protarchaeopteryx is coded as lacking a posteriorly extensive postantral wall and think the authors must have examined the material since it's certainly not illustrated or stated in the literature, and thus code it that way in their own matrix. But no, I've seen the specimen and the whole maxillary area is crushed so much that you can't even tell if the hole in it is the antorbital fenestra or just damage, let alone see any internal details of the thing. I'm not even going to go through their new character codings because I can't trust them one bit.

And by the way, contra Agnolin and Novas, their matrix generates 16210 most parsimonious trees of 1409 steps, not 145 trees of 1440 steps. I was suspicious about the added unenlagiine characters, both real and phantom, but it turns out that the trees have the same topology when either the two phantom characters or all five new characters are excluded. So I guess they weren't cheating for unenlagiine monophyly after all.

It's amazing how young most theropod specimens are

2012-01-17T04:54:00.000-08:00

Theropod analyses contain so many characters that are ontogenetically variable. Not just the numerous fusion characters (e.g. premaxillae, parietals, dentaries, cervical ribs, pygostyle, scapulocoracoids, pelvis, ischia, tibiotarsi, tarsometatarsi), but also less obvious things. Skull shape, orbit shape, maxillary fenestra position, postorbital orbital process presence, nasal rugosity, premaxillary tooth serration, pubic boot size, and more. We know that if you try to code juveniles for these characters, you get the wrong topology. Juvenile tyrannosaurines end up basally placed in that clade (Carr, 2005; near certainly Brusatte et al., 2009 for Alioramus); juvenile confuciusornithids end up basal to Pygostylia (Gao et al., 2008 for Zhongornis). And yet, basically no one accounts for this when coding. You might think that it shouldn't matter that much since comparatively few juvenile theropods are known, but I'm checking basically phylogeny-neutral fusions like braincase, neurocentral sutures and between sacral centra for my upcoming analysis and I'm surprised by just how few adult specimens we have. Among basal coelurosaurs, for instance-

Tanycolagreus' holotype has visible and open dorsal sutures, free sacral centra and is 63% the size of another specimen.
Coelurus' holotype has visible cervical and some dorsal sutures, open sutures on other dorsals and on caudals, and free sacral centra.
Ornitholestes' holotype has an unfused braincase, visible presacral and some proximal caudal sutures.
Nedcolbertia has open proximal caudal sutures on even the largest specimen.
Nqwebasaurus has open dorsal and caudal sututes.
Santanaraptor has visible caudal sutures.
Mirischia has open and visible dorsal sutures, open sacral sutures and sutured sacral centra.
Compsognathus' largest specimen has open and visible cervical sutures, visible dorsal, sacral and caudal sutures, and free and sutured sacral centra. The holotype is 62% its size.
Huaxiagnathus has open caudal sutures.
Sinocalliopteryx has a completely unfused braincase, at least visible cervical sutures and visible dorsal sutures.
Juravenator has open sacral and caudal sutures and free sacral centra.
Scipionyx has everything free of course.
In fact, among sampled basal coelurosaurs (excluding tyrannosauroids and maniraptoriforms), only Aniksosaurus seems to be perhaps an adult based on obliterated sutures on a cervical and a caudal.

Similicaudipteryx's holotype is probably an adult based on obliterated presacral and sacral sutures and has a pygostyle. Referred specimen STM22-6 is 64% its size (length proxied by femoral length) and also has one, but STM4-1 is 17% its size and doesn't. Zhongornis is 26% the size of adult Confuciusornis and didn't either, but specimens are known only 64% the size of the largest adults and have pygostyles. Did Sinosauropteryx have a pygostyle? Of course not you'd say, the holotype has a series of sixty-four unfused caudal vertebrae (the two larger described specimens don't preserve the distal tail). The largest specimen lacks fused neurocentral sutures on its proximal caudals, has sutured but unfused sacral centra, and did not fuse at least one sacral rib to its vertebra. So it's immature and the holotype 64% its size. Thus the holotype must be quite a bit less than 64% adult size which falls within the range of pygostyle uncertainty in Similicaudipteryx, and so would be better coded unknown. Of course I consider it unlikely given its phylogenetic position, but codings shouldn't assume that. Now remember that every ontogeny-related character has its own timing (that probably varied between taxa, but our sample sizes and description quality doesn't even let us go there), and you can see the problem.

References- Carr, 2005. Phylogeny of Tyrannosauroidea (Dinosauria: Coelurosauria) with special reference to North American forms. Unpublished PhD dissertation. University of Toronto. 1170 pp.

Gao, Chiappe, Meng, O'Conner, Wang, Cheng and Liu, 2008. A new basal lineage of Early Cretaceous birds from China and its implications on the evolution of the avian tail. Palaeontology. 51(4), 775-791.

Brusatte, Carr, Erickson, Bever and Norell, 2009. A long-snouted, multihorned tyrannosaurid from the Late Cretaceous of Mongolia. Proceedings of the National Academy of Sciences. 106(41), 17261-17266.

Please do a better job at alvarezsauroid taxonomy

2012-01-13T08:54:00.000-08:00

Among my Database updates were two new alvarezsaurid papers- Agnolin et al. (2012) describing Bonapartenykus and Xu et al. (2012) monographing Linhenykus. They both raise some interesting issues for the clade, showing alvarezsaur authors need to get their taxonomic act together.

Bonaparte (1991) initially put Alvarezsaurus in Alvarezsauria, but this was largely ignored since his Alvarezsauridae covered known taxa for almost two decades. Similarly, Livezey and Zusi (2007) used Alvarezsauroidea, but that was basically an afterthought in their huge inaccurate Aves analysis and like Alvarezsauria was redundant with Alvarezsauridae as then known. Hu et al. (2009) were the first to propose a phylogenetic definition for either and went with Alvarezsauroidea, defining it as a stem-based clade. Choiniere et al. (2010) then first published a proposed non-alvarezsaurid alvarezsaur (Haplocheirus), and followed Hu et al.'s choice. Later authors have similarly used Alvarezsauroidea, so we have consensus. Hoorah. Except... now Agnolin et al. want to start using Alvarezsauria again "in order to emphasize this morphologically distinctive theropod group", and propose basically the same definition, considering it a senior synonym of Alvarezsauroidea. Yet due to the ICZN, Bonaparte named Alvarezsauroidea the same time he named Alvarezsauridae, so there's no date or author priority, and plenty of big theropod clades end in -oidea (Coelophysoidea, Megalosauroidea, Tyrannosauroidea). As for the subjective level of morphological distinction, might I remind the authors they're writing in the twenty-first century. None of their reasons justify disrupting a taxonomic consensus.

Similarly, once people decided to follow the ICZN and use Parvicursorinae over Mononykinae, the former was given a node-based definition equivalent to the one Mononykinae had (Choiniere et al., 2010). But now the same group of authors (Xu et al., 2012) want to change it to a stem-based definition that ends up including more basal taxa like Linhenykus and Xixianykus too. Why? Because the latter "are morphologically very similar to members of this node-based Parvicursorinae" and "the most informative option is to treat Parvicursorinae as a stem-based taxon." But under their broader Parvicursorinae, the most basal forms will undoubtedly be very similar to Patagonykus, so by their same logic we would then expand the definition again. That's why we should be past these 50's-style typological arguments- evolution is a continuum. Again, even ignoring the faulty logic, phylogenetic taxonomy is only really useful if we leave the names and definitions alone so that when anyone says "Parvicursorinae" everyone will know where it goes in their phylogeny. It's as if people are using phylogenetic taxonomy, but don't really get the point of why it was introduced in the first place.

On a related note, Agnolin et al. propose Patagonykinae for Patagonykus and Bonapartenykus, but never properly define it with a node- or stem-based definition (and external reference taxon for the latter). Not that it's particularly useful, as the clade is united by all of two synapomorphies and has only been found in one analysis of course.

So far, the detailed alvarezsauroid analyses have been based on adding taxa to Longrich and Currie's (2009) little alvarezsaurid analysis, which results in Xixianykus and Linhenykus being basal as noted above. Instead, Agnolin et al. add Ceratonykus, Albinykus, Xixianykus and Linhenykus to Choiniere et al.'s big theropod analysis. Seems smart, until you realize that Choiniere et al. just left tons of known states uncoded. For instance, of all theropods, only Stokesosaurus langhami(!) is coded as lacking the traditional alvarezsaurid character of procoelous caudals. So the analysis is terribly untrustworthy. In any case, Agnolin et al. find a novel topology where Ceratonykus and Albinykus are basal (proposed by their original describers to be sister to the derived Mononykus and Shuvuuia respectively), Albertonykus is sister to Mononykus instead of being basal, and Linhenykus is sister to Shuvuuia instead of being basal. Compare below.

Previously published consensus-

|--outgroups
`--+--Linhenykus

   `--+--Albertonykus
`--+--Xixianykus
         `--+--Parvicursor
`--+--+--Shuvuuia
               | `--Albinykus
   `--+--Mononykus
                  `--Ceratonykus

Agnolin et al. (2012)-

|--outgroups
`--+--+--Ceratonykus
   | |--Xixianykus
   | `--Albinykus
   `--+--Parvicursor
`--+--+--Shuvuuia
         | `--Linhenykus
   `--+--Mononykus
            `--Albertonykus

While I don't trust the latter matrix as noted above, I am open to alternate alvarezsaurid topologies since Longrich and Currie's matrix is small, and hasn't included Albinykus or Bonapartenykus (I added all other known alvarezsauroids and reinforced Alifanov and Barsbold's suggested placement for Ceratonykus at least). What's irritating though is that Agnolin et al. go on to use their topology to propose and define two new clades. One is Mononykini (Mononykus olecranus <- Parvicursor remotus, Patagonykus puertai, Alvarezsaurus calvoi), based on one character which Parvicursor actually also has. Whoops! The other is Ceratonykini, defined as (Ceratonykus oculatus + Xixianykus zhangi). This is based on two characters, which only Xixianykus and Albinykus have. Whoops again!* Do I even have to say that Agnolin et al. don't test to see how many extra steps the old consensus topology takes to constrain in their analysis? Note that when applied to the standard topology, their definition of Ceratonykini ends up covering a much wider set of taxa, including Mononykini. So not only do we have the awkward nested tribes, but the concept is different than intended by Agnolin et al.. And the whole thing is based on meager character evidence that's incorrect anyway. Surely if you find a new topology from the consensus, you should wait until someone else finds it in a different matrix before applying a name to your novel clade. Unless your new analysis has strong support compared to the old topology, and you should pay attention to see if that support is based on accurate anatomy. And even if you feel the urge to name a new clade with strong and accurate support, please choose a definition that works with the old topology if possible. Agnolin et al. could have just called it Xixianykini and defined it as (Xixianykus zhangi <- Mononykus olecranus). That retains the same position in both trees (sister to Parvicursorinae), being unaffected by the controversial taxa, and Xixianykus actually has the proposed diagnostic characters. It's so easy.

So alvarezsaur authors, please don't redefine clades (especially for typological reasons) and please don't name new clades based on poor, inaccurate support, with definitions that don't work well in other topologies.

* Okay, I was writing this post at my parents' from memory of morphology, and now that I'm back home with the Ceratonykus pdf, it may also have the supposed ceratonykine characters (distal tarsals fused to metatarsals; metatarsals fused). At least the right metatarsus seems to, though the left is more ambiguous. Fusion is never explicitly mentioned, though they are called 'tarsometatarsals' [sic]. I was right about Parvicursor's second cnemial crest though, ha! In any case, I stand by my point that such low character support is problematic to name new clades from.

References- Bonaparte, 1991. Los vertebrados fosiles de la Formacion Ryo Colorado, de la ciudad de Neuquen y cercanyas, Cretacico superior, Argentina. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Revista (Seccion Paleontologya). 4, 15-123.

Livezey and Zusi, 2007. Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion. Zoological Journal of the Linnean Society. 149 (1), 1-95.

Hu, Hou, Zhang and Xu, 2009. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus. Nature. 461, 640-643.

Longrich and Currie, 2009. Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: Implications for the systematics and ecology of the Alvarezsauridae. Cretaceous Research. 30(1), 239-252.

Choiniere, Xu, Clark, Forster, Guo and Han, 2010. A basal alvarezsauroid theropod from the Early Late Jurassic of Xinjiang, China. Science. 327, 571-574.

Agnolin, Powell, Novas and Kundrat, 2012. New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of north-western Patagonia with associated eggs. Cretaceous Research. DOI: 10.1016/j.cretres.2011.11.014

Xu, Upchurch, Ma, Pittman, Choiniere, Sullivan, Hone, Tan, Tan, Xiao and Han, 2012. Osteology of the alvarezsauroid Linhenykus monodactylus from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China, and comments on alvarezsauroid biogeography. Acta Palaeontologica Polonica. http://dx.doi.org/10.4202/app.2011.0083

(Almost) Famous: I'm (mis)quoted in Feduccia's new book!

2012-01-03T18:17:00.000-08:00

Today Brad McFeeters informed me that Feduccia (2011) quoted me from a 2003 DML post in his new book! This is so great...

"Among the more amusing websites available for this group is the message board "Dinosaur Mailing List" (sponsored by the University of Southern California), whose mission is to "foster dialogue on science pertaining to dinosaurs." Although there is much of interest on the site, sifting the grain from the chaff can be a daunting task, and numerous amateurs use the site to vent their anger at dissenters, standing like Swiss Guards at the Vatican over all matters pertaining to dinosaurology, including entries in Wikipedia. After I was interviewed as Discover's "scientist of the month" in 2003 (the article was titled "Plucking apart the Dino-Birds"), a new thread appeared on the Dinosaur Mailing List site. "'Tis Time to Get Medieval on Alan Feduccia" stated: "Let Feduccia make his bold claims...Let the General go into battle with his army...But!!!! On the other side of the table will be sitting our knights." A follow-up entry even called for "a scientific crucifixion." It indeed seems that the weaker the science, the more contentious and vitriolic its adherents.[6]"

Going to the references, we find...

"6. Dinosaur Mailing List [dinosaur@usc.edu; sponsored by the University of Southern California]; M. Mortimer, "'Tis Time to Get Medieval on Alan Feduccia," Dinosaur Mailing List, 3 January 2003, 22:36:31-0880."

But wait, I never wrote that. As Brad noted, it was Kris Kripchak! He misread my reply! Feduccia can't even get quotation right. What's especially amusing is my response to Kris embodies respect for evidence and science, and the ideal of letting dissenters be heard-

"The problem of course, is that they are ignoring the evidence. It would be interesting if some scientific organization were capable of forcing scientists to address evidence against their theories, the alternative being to lose their degrees or something. But this would only lead to stagnation, as there are also many honest scientists out there who are trying to support potentially correct alternative theories, but might be prevented if they couldn't yet deal with the problems in their ideas. Critics force us to closely examine our theories and are useful for catalyzing paradigm shifts and theory modifications. I suppose a committee could be formed to examine cases and determine when someone was just stubbornly holding on to an idea with no reason, but it would all be too subjective to work. Methodologies are as controversial as morphologies are.

Besides, ABSRDists, despite their innumerable flaws, perform useful work for the paleontological community. They describe taxa (Cryptovolans, Scansoriopteryx, Eoenantiornis, etc.) and perform research (Ruben et al. on nasal turbinates, Harwell et al. on croc respiration) that may not have been performed as quickly otherwise. And mortality will see to it that defunct theories are banished from scientific journals eventually, as younger workers are less likely to believe falsehoods as evidence against them piles up.

Science works, it just takes time."

But hey Feduccia, if you really want a 2003 DML quote by me, here's one that's properly attributed and which I still stand by-

Nov. 26 "Indeed, Feduccia and his colleagues are either incredibly ignorant, or are horrendous liars."

Happy New Year! The Database is updated!

2011-12-31T18:35:00.000-08:00

Check it out! All the 2011 taxa are there. I'm off to party....

Surprise! Jeholornis palmapenis isn't valid.

2011-12-31T17:31:00.000-08:00

What's that you say? ANOTHER supposedly new Jehol basal avialan is just a junior synonym of a known species?! Shock! Gasp! This time it's none other than the armless Jeholornis palmapenis (insert priapic joke here). On the plus side, at least the description is better than others so far published, so this will help when coding Shenzhouraptor sinensis for matrices.

O'Connor et al. (2012) listed several characters supposedly distinguishing this taxon from Jeholornis prima.

The single preserved maxillary tooth and second empty alveolus contrast with IVPP V13274 (the prima holotype), V13550 and V13553 (both referred to prima), which have been reported to lack maxillary teeth. Yet jeholornithid teeth are often unpreserved due to their small size and low number, as seen by palmapenis' lack of dentary teeth (considered preservational by O'Connor et al.) and LPM 0193's (the Shenzhouraptor holotype) lack of any recognizable teeth. Even palmapenis only preserves one of the at least two maxillary teeth it had on that side. Thus the absence of maxillary teeth in other specimens may easily be preservational.

The presence of two pairs of anterior dorsal pleurocoels was listed as diagnostic (grading into a single pair posteriorly), but pleurocoel number often varies between different vertebrae and even sides of the same vertebra in theropods. Anterior pleurocoel number has not been described in any other jeholornithid specimen, but IVPP V13353 shows single pairs in dorsals nine and eleven, and three pairs in ten. Until palmapenis is shown to be consistantly unique in pleurocoel number, this character is not considered diagnostic.

Comparison of palmapenis ilium (top; after O'Connor et al., 2012) with prima (bottom; after Zhou and Zhang, 2003). Note the ventral edge of the postacetabular process (blue) is not significantly more concave in palmapenis. Note also the obvious breakage of the ilium (circled in red), making the dorsal border look highly convex. The upper right picture shows superimposed and flipped images of the anterior left ilium and posterior right ilium to show the dorsal margin (surrounded by green) is straight. Note that when the dorsal margins are lined up this way, the preserved posteroventral portion conveniently follows the outline of the other pubic peduncle.

The ilium is supposedly strongly convex dorsally, but it's clear the anterodorsal portion has merely been broken off, with no dorsal margin remaining anterior to the acetabular midpoint. The margin posterior to this is slightly convex as in other jeholornithid specimens. The anterior dorsal margin is preserved on the disarticulated left ilium, which forms a similar overall ilial dorsal convexity to other jeholornithids when rotated into place. Similarly, though the postacetabular process was described as strongly concave ventrally, the concavity is almost identical to that in IVPP V13353 (20% distance from line stretching from top of acetabulum to ventral postacetabular tip is 20% of ilial depth above acetabulum, compared to 19%) and other jeholornithids (the supposedly straight margin of IVPP V13274 looks slightly curved in the photo, and any difference would be insignificant in any case).

The dorsally curved ischium was also said to be diagnostic, but the distal ischium is unpreserved in the prima holotype, with the reconstructed portion being part of the tibia or fibula instead. Indeed, O'Connor et al. state ischial curvature is unclear in other Jeholornis specimens. LPM 0193 shows a dorsally curved ischium, albeit less so than in palmapenis.

In the tail, the transition point was stated to be more gradual (in central elongation) and posterior (at caudal seven instead of six) in palmapenis than IVPP V13550. Yet the transition point is also different in IVPP V13353, where the first elongated caudal is five, and IVPP V13274, where it seems to be at four (an unlabeled caudal is disarticulated adjacent to the last sacral). Differences in transition point abruptness are present as individual variation in other taxa, such as two nearly identical Microraptor specimens (CAGS 20-7-004 and 20-8-001), where the difference between lengths of caudals three and four is 9% in one and 53% in the other). Both caudal differences are thus more probably individual variation.

Finally, the diagnosis lists "elongated caudals possess chevrons with hooked articulations", but these articulations are not mentioned again and photos show normal, straight dorsal, anterior and posterior ends as in other paravians.

Of the diagnostic characters listed for prima by O'Connor et al., the ones not mentioned above are all unknown in palmapenis (except the robust dentary, which is true for all jeholornithids). In the text, the dentaries are said to appear unfused unlike the prima holotype, but they note this may be due to poor preservation. It may also be due to ontogeny, as palmapenis is smaller and has an unfused metatarsus. The text also states the ilium differs in having a bround rounded preacetabular process supposedly unlike IVPP V13274, but this is due to the latter being in medial view and not showing the ventral flange that would be lateral to the cuppedicus fossa, as seen in IVPP V13353 and LPM 0193.

So of the listed differences from prima, only the difference in maxillary dentulousness can even be plausibly considered true and not subject to individual variation. Ironically there are some valid differences not mentioned in the text. The dentary is a third deeper than the prima holotype and IVPP V13350, which is opposite the expected trend for a juvenile. The ischium slightly expands at its tip, unlike the Shenzhouraptor holotype. But since the first difference is not observable in the Shenzhouraptor type (whose anterior dentary angles beneath the skull) and the second difference is not observable in the prima type (whose distal ischium is broken off), these would form a weak differentiation from either species. As both character states are derived in Avialae, Shenzhouraptor and prima could not be united by their counterpart states. Instead, until they are shown to have a consistant variation between multiple specimens, the differences are more readily ascribed to individual variation as is found in any theropod known from large sample sizes (Allosaurus, Tyrannosaurus, Microraptor, Archaeopteryx). Jeholornis palmapenis is here made a junior synonym of Shenzhouraptor sinensis.

Referennces- Zhou and Zhang, 2003. Jeholornis compared to Archaeopteryx, with a new understanding of the earliest avian evolution. Naturwissenschaften. 90, 220-225.
O'Connor, Sun, Xu, Wang and Zhou, 2012. A new species of Jeholornis with complete caudal integument. Historical Biology. DOI: 10.1080/08912963.2011.552720

Merry Christmas! It's Xu's Thesis

2011-12-26T22:55:00.000-08:00

I received a wonderful Christmas present this year- a copy of Xu's (2002) thesis on Liaoning deinonychosaurs which I've wanted for a decade now. It's referenced in most of Xu's publications, but not in many others, and since it's not available in pdf, the info is difficult to come by. This is one of the best publications on theropods I've read, so I'll sum up the contents here.

The first section is an osteology of the holotype of Sinornithosaurus. The cranial and pedal sections have been published (as Xu and Wu, 2001 and Xu and Wang, 2000), but the axial description was most interesting to me. It preserves 21 presacral vertebrae and the first nine caudals, yet these are not easily identified in the original tabloid description, unlike the pectoral girdle, manus and pelvis, which show most of their characters in the original figures.

The second section is an osteology of Microraptor's holotype, but also a specimen otherwise unmentioned in the literature- incomplete skeleton IVPP V13475 from the Jiufotang Formation, missing only some caudal vertebrae and the left manus. This provides us with the Microraptor skull description I've been waiting for, and is what the reconstruction in Xu et al.'s (2011) paper is from, and what many of the codings for Microraptor in Xu and Zhang's (2005) matrix are from. The rest of the description is less useful now that we have Hwang et al.'s (2002), but does feature interesting details like a large coracoid fenestra as in Sinornithosaurus and a straight pubis unlike other microraptorians.

The third section is an osteology of the then-undescribed Graciliraptor, so "Graciliraptor lujiatunensis" Xu, 2002 is a nomen nudum used prior to 2004. The description is better than the published version, but not by much since it was published in a real journal, and the specimen is fragmentary to begin with.

The fourth section is my favorite- a detailed osteology of the holotype and paratype of Sinovenator. The species name is given as changae, as opposed to changii, since Li noted it was grammatically incorrect. Creisler noted this on the DML that year too, but suggested changiae. Since it's named after a woman named Chang, I think changae would be right, but as I note on the Database, the Fourth Edition of the ICZN no longer requires emendations based on this reasoning (Article 31.1.3). Nomenclature aside, the description is excellent and includes such needed things as an anterolateral view of the coracoid, posterior view of the braincase, and multiple views of presacral vertebrae. Since we really don't have any detailed published descriptions of basal troodontid anatomy, and Sinovenator is basically complete (missing most of the palate, the quadratojugal, part of the mandible, half the cervicals, the post-26 caudals, ribs, and part of the hand), this section is vital to anyone studying paravian phylogeny.

The next section is about the feathers of Liaoning dromaeosaurids, which I normally would find boring, except that among the specimens described and photographed are Microraptor gui paratypes IVPP V13477 and V13320. Of course, M. gui was a year away in 2002, so Xu refers to them as Sinornithosaurus sp. and Microraptor sp. respectively. Interestingly, IVPP V13320 has completely serrationless teeth, while most Microraptor specimens have only distally serrated (posterior) teeth, and NGMC 00-12-A has posterior dentary teeth with serrations on both carinae.

The last section is one I would normally be very excited about- the phylogenetic analysis. But it's basically the same as Xu and Zhang's (2005) with one less character and without Scansoriopteryx, Shenzhouraptor and Pedopenna (careful readers will note two mentions of Shenzhouraptor as an unnamed new bird without a pygostyle and one mention of Zuolong as an unnamed basal coelurosaur). Xu runs lots of variations (cranial only, postcranial only, only basal taxa, only derived taxa, excluding various taxa) that would have been very interesting back in 2003, but since so many new taxa are lacking, are now more of historical interest like my Evaluating Phylogenetic Analyses section. One good thing is that he describes several of the characters in depth and even provides graphs showing ratio distributions, so that they can be evaluated better than most TWG characters.

Xu ends with extensive measurement tables for the specimens described in the osteologies, but unfortunately not for the M. gui paratypes. I would have liked more illustrations, but Xu's descriptions are top notch, and are badly needed for taxa described in tabloids like Sinornithosaurus and Sinovenator. I don't know why most of this material was never published, since it's been written up for almost a decade now. Similarly, I can only hope something of this caliber is written up for Beipiaosaurus and Mei. Unfortunately, I only have a hard copy, so cannot send pdfs yet.

References- Xu and Wang, 2000. Troodontid-like pes in the dromaeosaurid Sinornithosaurus. Paleont. Soc. Korea Special Publication. 4, 179-188.
Xu and Wu, 2001. Cranial morphology of Sinornithosaurus millenii Xu et al. 1999 (Dinosauria: Theropoda: Dromaeosauridae) from the Yixian Formation of Liaoning, China. Canadian Journal of Earth Sciences. 38, 1739-1752.
Hwang, Norell, Qiang and Keqin, 2002. New specimens of Microraptor zhaoianus (Theropoda: Dromaeosauridae) from northeastern China. American Museum Novitates. 3381, 1-44.
Xu, 2002. Deinonychosaurian fossils from the Jehol Group of Western Liaoning and the coelurosaurian evolution. PhD Thesis. Chinese Academy of Sciences. 325 pp.
Xu and Zhang, 2005. A new maniraptoran dinosaur from China with long feathers on the metatarsus. Naturwissenschaften. 92, 173-177.
Xu, You, Du and Han, 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature. 475, 465-470.

Top 10 Most Poorly Described and Illustrated Mesozoic Theropods

2011-12-02T05:48:00.000-08:00

Look at that, I managed to skip a month between posts. The hazards of coding, illness and other such excuses. Here's a quickie that was fueled by my annoyance at any significant primary literature while coding Adasaurus. These are the theropods whose publically available information is the most paltry compared to the completeness of their remains, and have been officially described already in the literature. The relative importance of the taxon isn't a factor, and taxa whose remains are lost aren't considered due to the impossibility of their redescription.

10. Anserimimus
Anserimimus' holotype is a skeleton missing only some cervicals and the skull, but only the scapulocoracoid, manus and metatarsus were described and illustrated by Barsbold (1988). Kobayashi and Barsbold (2006) helped a bit, as does Bronowicz's (2011) fragmentary but well described specimens. But what keeps this from scoring higher is the availability of good photos of the mount (e.g. this) and Kobayashi's (2004) coding it for several matrices.

9. Tie between Cristatusaurus, Deltadromeus and Afrovenator
These taxa all have a common theme- Sereno described them (well, he described Suchomimus, which I sink into Cristatusaurus). Published by the king of the Science tabloid, featuring a Paulian skeletal and several zoomed in line drawings, these taxa have yet to be redescribed in detail. While there are photos of mounted skeletons available, these are all casts. The best source of information on these are the matrices of Rauhut (2003) and Benson (2010).

8. Aucasaurus
Basically complete, but only the proximal tail, arm and lower hindlimbs have been illustrated and briefly described. Recently, the braincase was also described, though I lack that paper so far. Ceratosaur matrices like Carrano and Sampson (2007) have some info.

7. Inosaurus
Known from quite fragmentary remains, but very poorly described and only illustrated by two partial vertebrae (apparently my tracing survives unattributed online). Is it even dinosaurian?

6. "Chilantaisaurus" zheziangensis
Dong (1979) gave this proximal tibia and partial pes a fairly useless description and illustrated two pedal digits in ventrolateral view and curving towards the viewer. :| Therizinosaurian affinities have been suggested, but it's not been examined since.

5. Kaijiangosaurus
Only a few vertebrae, pectoral girdle and proximal/distal metatarsal outlines have been illustrated, and the description has yet to be translated from Chinese. An online photo shows a lot more is known, but also that size differences mean more than one individual/taxon are present.

4. Conchoraptor
Ah, Conchoraptor. You might be asking how can this be obscure when there are so many skeletons casted. I've even seen two in person. The problem with Conchoraptor is that it's unsure just which specimens belong to it, besides the holotype (of which we have illustrations of the skull, and a manus and metatarsus that presumably belong to it or a paratype). None of the articulated skeletons photographed online have the right manual proportions or slender metatarsal II, and crestless skulls like ZPAL MgD-I/95 (the one described by Osmolska, 1976 and which Kundrat has recently been describing braincase details of) and the one on Witmer's lab page identified as "Ingenia" could belong to other oviraptorids. No one has ever provided a modern diagnosis, described the holotype in any detail or justified the referral of other specimens. This makes depending on matrices more risky than for other taxa listed here, since their OTU could be chimaerical for all I know.

3. Rinchenia
This has been illustrated in the literature even more seldomly than Conchoraptor, since at least ZPAL MgD-I/95 has papers dedicated to it. We only have the skull, mandible, overly schematic ilium and a single caudal vertebra illustrated. Lucky for us, Auditore was able to obtain photos of the holotype and illustrate it as detailed by Cau on his blog. As for Conchoraptor, Norell et al. (2001), Lu (2004) and Maryanska et al. (2002) all provide codings, which can be trusted more for Rinchenia since there's only the holotype (though I note a recent incorrect trend of referring IGM 100/42 to it).

2. Adasaurus
The muse for this post only gets second place. For Adasaurus we must depend on a few schematic drawings (pelvis, metatarsus, pedal digit II), since Barsbold (1988) neither described it besides noting a couple features, nor does he allow photos to be circulated. There was a photo of the holotype online which has since disappeared, but shows Barsbold's pelvis illustration is inaccurate, and to make it worse Kubota (pers. comm. to Senter, 2010) indicates the supposed small sickle claw doesn't belong. I'm just hoping Kubota plans to redescribe the taxon like Kobayashi did for Barsbold's basal ornithomimosaurs. Until then, we depend on codings from Norell et al. (2001), Senter (2007) and Longrich and Currie (2009), and a few scattered notes. Hopefully Turner et al.'s upcoming dromaeosaurid monograph has some juicy photos.

1. Chilantaisaurus? sibiricus
There are a lot of fragmentary taxa known from a tooth or a vertebra that are poorly described (usually in a useless archaic way) and illustrated in a photo from a single view. What makes sibiricus stand out is that Riabinin (1914) didn't even identify which element the holotype was, let alone try to describe its features. He just said it was hollow and belonged to the limb of a fairly large theropod, probably a megalosaurid (named as Allosaurus? sibiricus). Even worse, he didn't illustrate it, only providing six measurements (proximal width 48 mm, proximal depth 39 mm, distal width 68 mm, distal depth 62 mm, cavity width 22 mm, cavity depth 17 mm). Huene (1932) identified it as a distal metatarsal IV without rationale, but said only that it did not permit exact characterization and probably belonged to an allosaurid (renamed Antrodemus? sibiricus). Molnar et al. (1990) then said it was "almost identical with that of C. tashuikouensis in form and proportions of the distal condyle", so questionably referred it to that genus. You now possess the entirity of published information on sibiricus. Makes the available information on Adasaurus seem like an overflowing feast.

Cladistics good, Aurorazhdarcho bad

2011-10-25T00:46:00.000-07:00

Today I'm reporting on two papers, one good, one bad. Both involve cladistics, but besides that are basically unrelated.

Tom Holtz notified the DML of a new paper by Brazeau (2011). I highly recommend anyone making or examining a cladistic analysis read this work. He basically outlines many of the problems I describe in the Evaluating Phylogenetic Analyses page of my website.
- Don't make "pseudo-ordered" characters of the form "bone x absent (0); bone x lacks feature A (1); bone x has feature A (2)", because if it's unordered PAUP has no reason to know to group all taxa with bone x together. If it's ordered, it solves that problem, but has the probably undesired effect of assuming feature A is related to the loss of the bone.
- Don't have multiple characters implicitly coding for the same thing, with absence of that thing a state in addition to states coding for the presence/absence of a feature on the thing. So "bone x absent (0); bone x present (1)" and "bone x absent (0); bone x present and without feature A (1); bone x present and with feature A (2)" should not both exist. Have one character for the bones's absence/presence, and another character for each feature of the bone. Just code taxa without the bone as inapplicable for characters about that bone's feature. But be sure to set PAUP to collapse 0 length branches if you use inapplicable characters (TNT and NONA collapse them automatically).
- Don't make compound characters. Each character should code for only one variable.
- Remember that "0" does not mean "primitive". 0 has to be a distinct state just like 1, 2 or any other number. So don't make a character like "deltopectoral crest shape not described by any of the other states (0); crest round (1); crest triangular (2)", because there are lots of other shapes besides round and triangular, but PAUP could easily make state 0 synapomorphic for some clade. That could end up grouping taxa with rectangular, pentagonal, etc. crests together as having the same condition, which is clearly not justified.
- As a consequence of this, making ordered multistate characters is better than making a series of less inclusive bistate characters.

The second paper was announced today- the description of a new taxon of pterosaur. Frey et al. (2011) described Aurorazhdarcho, which is a damned cool name. Unfortunately, the paper goes downhill from there.

First, they assign Aurorazhdarcho to the new family Protazhdarchidae. Are there really people who still think you can make up a family-group name that's not eponymous with an existing genus? Without a Protazhdarcho (which doesn't exist), there can be no Protazhdarchidae. And Frey et al. can't use the excuse that Protazhdarchidae is "just a clade" since they explicitly say "nov. fam." and "we propose to erect a new family, the Protazhdarchidae..." Tim Williams brought up the possibility on the DML that maybe the genus was originally named Protazdarcho and later changed, but the family name wasn't caught in time (though barring a VERY last minute change or editorial messiness I would hope the peer reviewers would still catch it), and if that's the case I apologize to the authors for this insulting paragraph. Regardless, my insults in the next two paragraphs still apply. ;)

Second, Protazhdarchidae is monotypic, so is useless anyway. Maybe I was too hasty in dismissing Jaime's suggestion for purely monotypic theropod families in the year 2100, since apparently it's not just Ji and other Chinese workers who are stuck in the archaic typological mindset. The taxonomic world has moved beyond subjective difference being a reason to name a new clade/grade, please join the rest of us in the 21st century.

Third, Frey et al. include the highly flawed section "Problems with cladistic analysis". Note they don't actually include Aurorazhdarcho in an analysis. Why not? "The main reason is that the low wing attachment is reason enough to align the specimen with the azhdachoid construction, which separates the group from all other Pterosauria." I suppose Halloween IS a good time for Huene's ghost to rear its head, insisting on the importance of key characters. We then get this lovely gem-

"If the low position of the glenoid fossa is regarded as original tetrapod, the azhdarchoid pterosaur construction has retained the low articulation of the front limbs and thus must have separated in the early history of the Pterosauria, possibly during the Triassic. Then, the high wing articulation could have evolved several times independently within the Pterosauria. If the low wing articulation is regarded as derived, the re-development of the primitive position of the glenoid fossa has to be explained. To resolve this question, a reinvestigation of the shoulder girdle of early Pterosauria would be necessary. For now, this problem remains unresolved pending an engineering approach concerning the consequences of low wing attachment, too. Hence, the character should be dismissed because of its evident functional impetus and unclear origin (Frey et al. 2003a)."

Did anyone else hear a distinguished gentleman in a sepia photograph read the above statements? A single primitive character does not mean an entire clade is basal- we must examine the entire set of characters to determine which are more likely to be reversals or convergences. We don't have to explain why any character evolved, nor should our ability to hypothesize why one state could evolve from another affect our choice in character polarity. I'm very interested in what exactly all the characters we use were actually good for, but the analysis comes first THEN the evolutionary scenario. Frey et al. are guilty of the same thing BADists are- wanting to know the scenario first and basing the phylogeny off that. As for their last sentence, since every(?) character that's not the result of genetic drift has some functional importance (and how would we ever test that in extinct taxa?), that's not a reason to exclude them from analyses. And since origins are only made clear once you run an analysis, excluding a character due to its 'unclear origin' is just nonsensical.

The rest of their "problems" are basically of the form "character x influences character y since both are parts of some functional whole, and until we know how these influences work, we shouldn't include either character in cladistic analyses." So glenoid position influences deltopectoral crest shape and so on. Frey et al. are fundamentally wrong in their demand to know function before phylogeny, and that anatomy alone isn't enough to know when characters are strictly correlated. All you need to do is check the matrix to see if every taxon with character x also has character y, and if every taxon without x also lacks y. Now if you do find exact correlation and it's logically impossible to have a condition with x and without y and vice versa, THEN you can delete the character. Otherwise you might have a character complex like the paravian sickle claw where claw hyperextendability, size and curvature are certainly all functionally related, but should still be coded as separate characters since they're independent (e.g. Archaeopteryx lacks large size, Borogovia lacks strong curvature). Now I suppose some characters might be correlated due to combinations of osteology that are only logically impossible once soft tissues are taken into account, and not just simple muscular biomechanics as Frey et al. suggest, but even such details as involving expression of the same gene at the same time. Yet we'll never know most soft tissue anatomy for most fossil taxa (and even living taxa are poorly studied in this regard), so to rule out such correlation in our matrices is basically impossible. We can either try to determine phylogeny now while excluding the logically correlated characters, or wait forever until we have fully examined a complete living growing example of each taxon to eliminate the possibility of correlation for each character. I vote for the former.

Incidentally, given Frey et al.'s lack of a modern phylogenetic perspective, I don't trust their placement of Aurorazhdarcho in Azhdarchoidea. Maybe it is, I'm not qualified to say, but I await the results of someone using a modern approach.

References- Brazeau, 2011. Problematic character coding methods in morphology and their effects. Biological Journal of the Linnean Society. 104, 489-498.

Frey, Meyer and Tischlinger, 2011. The oldest azhdarchoid pterosaur from the Late Jurassic Solnhofen Limestone (Early Tithonian) of Southern Germany. Swiss Journal of Geosciences. DOI: 10.1007/s00015-011-0073-1

Xiaotingia commentary, is Archaeopteryx a deinonychosaur?

2011-10-21T06:19:00.000-07:00

I just wrote this for the DML and figured it could be useful to post here.

The majority view, as in the conclusion found by almost every cladistic analysis which has tackled the problem, is that Archaeopteryx is a basal avialan. The recent controversy has been over the analysis in Xu et al.'s (2011) description of Xiaotingia. This is a version of the Theropod Working Group analysis which goes back to Norell et al. (2001). Specifically Xu et al. (2011) added a few taxa and several characters to...
- Zhang et al.'s (2008) analysis which added Epidexipteryx and a few characters to...
- Senter's (2007) analysis which completely recoded and added many characters and taxa to...
- Kirkland et al.'s (2005) analysis which added several characters and a few therizinosaurs to...
- Hwang et al.'s (2004), which is based on Xu et al.'s (2002), which is based on more analyses still all the way back to Norell et al. (2001).

So it's a re-re-re-re-re-analysis of a huge dataset. Running this dataset with Xiaotingia results in Archaeopteryx being a basal deinonychosaur instead of a basal avialan. Note this isn't a big move, since Deinonychosauria and Avialae are sister groups. It just moves from the base of one group to the base of the other. Note also that despite what the hype would indicate, this result isn't very well supported. Forcing Archaeopteryx back to its normal position as a basal avialan only takes TWO more evolutionary steps. That's not significant at all, and furthermore the analysis itself is flawed as detailed below.

When you run an analysis like this, certain characters need to be "ordered". So that for instance, taxa with six sacral vertebrae are seen as intermediate between taxa with five and taxa with seven sacrals. If you don't order the character, "six sacrals" is counted as a character that has no definite relationship to other numbers of sacral vertebrae, so you'd get weird results like grouping Rahonavis and Shenzhouraptor together to the exclusion of more derived birds because of their shared primitive sacral number. Also, ordering changes the amount of steps a character takes to evolve, since if it's unordered, you can go from five to nine sacrals as easily as you can go from five to six sacrals. When we try to find out if Xu et al. ordered their characters, we have to follow the lineage of analyses all the way back to Kirkland et al.'s (2005) version, which only says one character was ordered but doesn't say which. Xu et al. seem to ignore that anyway, since I get their results by running their analysis unordered. Running Xu et al.'s analysis with all characters ordered adds over 100 steps, which of course completely overpowers our two step difference we noted above. While not every character should be ordered, many should be. Importantly, when characters are ordered, Archaeopteryx comes out as a bird.

So how much of Xu et al.'s result is due to not having the right characters ordered? We don't know unless someone goes through the tedious steps of looking through all the characters and choosing which should be ordered. You can see how this could be important for Archaeopteryx, since any intermediate state it has between birds and deinonychosaurs will be counted as equally different from both instead of being a bit closer to birds (assuming the deinonychosaurian condition is primitive).

Another problem is that Xu et al.'s analysis doesn't include all of the relevent taxa and characters that other versions of the analysis do. Senter's newest (2010) analysis (which is a modification of his 2007 one) includes most of the same taxa but has many new codings and takes seven more steps to place Archaeopteryx in Deinonychosauria. Zanno et al.'s (2009) analysis (which has a rather different lineage going back to Hwang et al. 2004 and so doesn't include any of Senter's numerous modifications) contains a different mix of characters, adds Mahakala and Shanag, but lacks scansoriopterygids, Sapeornis, Protopteryx, NGMC 91 and Bambiraptor. Forcing deinonychosaurian Archaeopteryx is six steps longer in it. Makovicky et al.'s (2010) analysis (which is more similar to Zanno et al.'s) includes yet a different mix of characters and taxa needs eight more steps. Most recently, Turner et al. (2011) have a TWG-based analysis centered on deinonychosaurs and birds, including taxa not found in the Xiaotingia analysis like Hesperonychus, Graciliraptor, Tianyuraptor, Austroraptor, Mahakala, Jinfengopteryx, two undescribed basal troodontids, Jixiangornis and a lot of birds. Based on their taxon sample I bet they also included the numerous bird-related characters of Clarke's analyses. And this analysis found Archaeopteryx to be a bird, though I can't say how well supported that is since they haven't released their data matrix yet (grrr).

So we can see that most analyses find Archaeopteryx to be 6-8 steps more likely to be a bird, while Xu et al. found it to be 2 steps more likely to be a deinonychosaur. Each analysis includes some data others don't, and all have miscodings. Until someone combines the information (which I'm finishing up), we won't know if say adding Xiaotingia to Turner et al.'s analysis would make Archaeopteryx a deinonychosaur, or if adding Jinfengopteryx to Xu et al.'s analysis would make Archaeopteryx a bird.

Until that time, I'd say it could be either, but that both the number of analyses and the strength of support in those analyses slightly favor it being a bird.

Theropoda in the Amazing Year 2100

2011-10-15T19:22:00.000-07:00

One of my pet peeves is the cavalier attitude many dinosaur paleontologists have recently in regard to the priority and validity of old taxa. Whether it's lazy dismissal of genera as nomina dubia without an analysis showing this is true, dumping family-level names based on supposed nomina dubia despite the ICZN having no rules about this, making up new definitions for established clades, or just plain old replacement of clade names because the eponymous genus isn't as complete or deeply nested as another. If this trend continues, we may face the following horrifying vision of the future...

Theropoda
- Coelophysoidea (based on a complete neotype for Coelophysis bauri, the only known material for the first 66 years having been ignored as archosaur scrap; IT'S ALREADY TRUE!)
- Sinodilophosauridae (people still refuse to use Dilophosauridae, but the describers of what was originally Dilophosaurus sinensis came up with their own name for this clade)
- Averostra (because enough people misused Bakker's Neotheropoda so that they forgot he created it for this node and started using a term published 16 years later instead)
-- Ceratosauria
--- Majungasauroidea (Abelisaurus was deemed too fragmentary, and Carnotaurus is still only known from one specimen. Majungasaurus itself is now based on a complete neotype found in 2068)
---- Masiakasauridae
---- Majungasauridae
-- Tetanuriformes (someone finally got enough followers after redefining Tetanurae to be less inclusive, thus Tetanurae has different meanings depending on what year a paper was published)
--- Suchomimia
---- Tayntonsauridae (after a incomplete articulated megalosaur was found in Megalosaurus' type beds, it was named to 'solve' the confusion surrounding Megalosaurus' association. All Megalosaurus remains were then referred to Tayntonsaurus)
---- Suchomimidae (Yes, ignoring Spinosauridae, Baryonychidae, Irritatoridae and Cristatusaurus)
--- Tetanurae
----Sinraptoroidea (after Allosaurus fragilis was shown to be a nomen dubium, people incorrectly said a family level name couldn't be based on it)
----- Sinraptoridae (no comment needed)
----- Neoallosauridae (people declared Allosaurus, Labrosaurus, Creosaurus and Epanterias to be undiagnostic in a footnote of the paper describing Big Al as Neoallosaurus in 2035)
----- Carcharodontosauria
------ Neovenatoridae
------ Acrocanthosauridae
------ Shaochilongidae
------ Tyrannotitanidae
------ Carcharodontosauridae (ignoring the stable stem-based definition of Carcharodontosauridae, people kept redefining it to be less and less inclusive)
---- Tyrannosauroidea (despite including the following two families, both named prior to Tyrannosauridae...)
----- Coeluridae
----- Compsognathidae
----- Tyrannosauridae
---- Avesternes (someone named it in 2019 and people started to ignore Maniraptoriformes)
----- Ornithomimosauria (based on a neotype for Ornithomimus edmontonicus, even though O. velox was the type species and brevitertius has priority over edmontonicus)
----- Eunothronychia (Therizinosauria was defeated the same way it gained usage, once graffami was given its own genus)
----- Citipatia (Oviraptor was too fragmentary, so the clade was renamed once Citipati's holotype was fully described in 2023. IGM 100/42 remains undescribed and called the Zamyn Kondt oviraptorid as of 2100)
----- Bimedicamentodontidae (Troodon is a long forgotten name, and no the family hasn't been subdivided yet despite there being 73 described diagnostic genera)
----- Dromaeosauridae (miraculously unaffected, but Barsbold's estate owns Adasaurus, which no one is allowed to circulate holograms of)
----- Shuvuuiformes (because of... well, you get the drift by now)
----- Birdia (we finally got sick of the semantic arguments)

Only you can prevent this terrifying prediction from becoming reality. Support priority, follow the ICZN until another code is viable (the Phylocode remains unofficial as of 2100, but rumors are Phylonyms is almost complete and that it will start as of 1-1-21xx), and remember a named taxon is valid until shown otherwise by a detailed redescription and comparison.

Planet Dinosaur Review

2011-09-17T21:28:00.000-07:00

Since I reviewed Dinosaur Revolution, I might as well tackle the other big dino documentary that came out this month. As with Dinosaur Revolution, this review only covers the first episode, which in this case was about Cenomanian North Africa.

Planet Dinosaur's special effects range from decent to sad. While I could go on about the little details like Ouranosaurus chewing like a mammal, having depressions where its laterotemporal fenestrae are, Microraptor lacking primaries attached to its second finger and having wings which are too short, etc., the simple truth is that the dinosaurs are less accurate and less believable as real objects. The maniraptorans (Troodon, Microraptor, Epidexipteryx) are especially poor. That's not to say it's all bad. The Rugops (possibly an Aucasaurus from the Auca Mahuevo episode) and Sarcosuchus look pretty good, the Spinosaurus is decent except for its short tail, and the Ouranosaurus dying had nice motions and rapid breathing. Seeing this show really made me realize how good the models and animation were in Dinosaur Revolution though. It's such a shame the talent/money spent on the latter couldn't have been used for a program like Planet Dinosaur.

As far as behavior goes, it was refreshing to see dinosaurs acting like dinosaurs. There are a few stupid things, like Spinosaurus eating part of a fish, then leaving to catch more ("with prey plentiful, Spinosaurus can afford to be wasteful"). Or Rugops' subsequent portrayal as an obligate scavenger. Or Spinosaurus slashing the fish with its hands, only to eat tiny bits at a time. But at least nothing they do is human-like. The behavior is largely defended by reference to actual studies (see below), and the show does a good job of making a story based on these. The larger narrative of Spinosaurus being the largest and last spinosaurid and dying from climate change was flawed because Late Cretaceous African dinosaurs are poorly known, and Hone et al. (2010) and Candeiro et al. (2004) described Santonian spinosaurids. But Candeiro et al.'s conclusion was doubted in their 2006 paper and Hone et al.'s study is quite new. Bearing in mind I don't know how accurate the paleoclimatology was, the larger story felt more plausible than Dinosaur Revolution's apparently tacked-on story of how dinosaur parenting helped their success.

My favorite part of Planet Dinosaur is that it manages to explicitly incorporate numerous journal articles. These are shown in informational panels with the year of publication, age, country, and figures from the original articles or photos of specimens referenced by them. They even managed to rotate one of Stromer's Spinosaurus vertebra drawings in 3D, haha. We have Stromer (1915), Dal Sasso et al. (2005), Amiot et al. (2010), Dal Sasso et al. (2009), Sereno et al. (1996), Tanke and Currie (2000), Sereno et al. (2008), Kellner (2004), Charig and Milner (1986), and a biomechanical strength analysis of Carcharodontosaurus' jaws. I don't know how much I agree with some of the conclusions (like amphibious spinosaurids), but at least they're actually from the scientific literature and not just random made-up possibilities.
There are ocassional errors, like overlaying a tyrannosaurid dentary on Sinraptor's skull, or using Stromer's reconstruction as the basis of the Spinosaurus skeletal, resulting in one of the worst reconstructions I've seen. It's good they knew to tilt it horizontal and give it the right skull, but the anatomy! Sacral neural spines lateral to the ilium, the femur articulating with the postacetabular process, two sets of pubes... I could insult it all day.

Please put this travesty out of its misery

And yet other details of their informational panels are accurate, such as Irritator and Siamosaurus being inconspicuously listed as additional spinosaurids on the map. Overall, it's quite good. I actually learned what Onchopristis was, and that there's a partial Spinosaurus maxilla with an Onchopristis tooth embedded in it (not just MSNM V4047 with its embedded vertebra). There's also apparently a Spinosaurus neural spine found in 2008 in Morocco that had been broken in life, which I had never heard of. Any time a dinosaur show manages to teach ME something, I'm impressed.

So I quite liked Planet Dinosaur. It's almost the exact opposite of Dinosaur Revolution- generally inaccurate restorations behaving fairly realistically, packed full of references to specific discoveries in the literature, telling us what we know and why. I'll be watching the following episodes, and contra my earlier statement I'll probably tune in to the other Dinosaur Revolutions too. I'll just have to treat the latter like the Transformers 2 of dinosaur programs- pretty to watch, but turn off your brain. On the other hand, I'll be interested to see if Planet Dinosaur presents any more discoveries I hadn't heard of.

Dinosaur Revolution review

2011-09-13T04:19:00.000-07:00

Well, that was painful. I decided to join the trend and review the show that's been so hyped- Dinosaur Revolution. Little did I know my yearly allowance of eyerolls would be used up. I only watched the frirst episode "Evolution's Winners" and frankly have no desire to sample more.

First the good. The models were usually excellent, with non-pronated hands and all that good stuff. I especially enjoyed the dilophosaurian snouts on the Cryolophosaurus, and the Mongolian mammals which weren't just shrews or mice. I also liked the homage to Dryptosaurus and Ceratosaurus artwork in the Cryolophosaurus section (though I don't think they could really stand on their tails, given how most theropod chevrons look). The Gigantoraptor's feathering was more problematic, as it seemed more like a naked theropod covered in feathers than an actual feathered creature like a bird, where body outlines are hidden and feathers interact and fold. Its wings were always held out in front, which for a display is fine, but even the female who wanders up is posed this way. The animation itself was a mixed bag. Most moved smoothly, but the Saurosuchus looked unnatural for instance. Similarly, the rendering was good for most, but the therapsids in the opening seen looked plasticy. What's that you say? My "good" paragraph's actually mostly full of criticisms? Guess that prepares the way for the rest of the review...

What made Dinosaur Revolution most difficult to watch is the rampant anthropomorphism. Basically none of the subjects actually behaves like a reptile, or a bird, or even a non-ape mammal for that matter. They're chock full of human mannerisms. You can always tell what they're supposed to be feeling, as if brains that size could even house such emotion. But it's not just behavior. My jaw dropped at the blatant 'sexy eyelash' marks on the female Eoraptors. Why not just go the whole hog and give them real eyelashes they can flutter alluringly? Then the male's heart (shaped like a heart of course) could project from its chest like a piston. Would have been almost as realistic as the expectant smile he shows as she approaches in the actual program. Even ignoring the behavior, the plotlines have so many "entertaining" improbable portions, like the Eoraptor unwittingly throwing a therapsid into Saurosuchus' mouth, that any illusion you're watching reality is destroyed. And what was up with that swarm of hostile flies chasing the Antarctic fauna and killing the lizard... for blood! Is this a 1950s horror movie or something?

Which would have all been excusable if the show at least taught us something. Then it'd be a Dinosaur Train for adults, which wouldn't be my idea of a good program to watch, but would at least educate the part of the public that finds documentaries boring. But no, I don't think there was any actual paleontological data contained in that hour, besides most of the portrayed anatomy and a few basic facts like "birds are dinosaurs" and "Cryolophosaurus is from Antarctica". I say "most" because while the models were largely accurate, they sometimes contained some fictional aspect. The rhamphorhynchoid tail fin on the female Eoraptors, for instance. Or the highly elaborate wattles and soft horns on the male Gigantoraptor. And when it comes to behavior, we have bower-building Eoraptors, color flushing Cryolophosaurus which killed the young of rival males, a stomping and twirling Gigantoraptor mating dance, Glacialisaurus which lived in harems (which we so know from the partial hindlimb...), etc. It's not that these soft parts or behaviors are impossible, but Joe Public's only going to remember Gigantoraptor as "that goofy rainbow-colored thing that dances" or Eoraptor as "those raptors that cutely chirp and build mounds to select mates, and then care for their baby who adorably falls down, awwww". So you're emphasizing the fictional aspects of these animals, while not going into any of the actual known interesting facts about them.

But maybe the show could have retained some use if all of this human-like/fictional appearance and behavior was there to illustrate some greater true scientific fact, that even network execs think viewers could remember. Alas, no. The implication of the Eoraptor portion was that dinosaur success was due to more complex parental care, but my impression has been that evidence for such care is limited to maniraptorans, supposed evidence for care in hadrosaurs (and thus Ornithischia) has been refuted, and that baby sauropods were too small to associate with adults and aren't apparent in herd trackways. And even the mosasaur cares for its babies enough to get revenge on sharks for eating them (vengeance is such a widespread trait in squamates...). As does the Cretaceous mammal, more realistically. If you want to make the point dinosaurs were probably often brightly colored with display structures as the Gigantoraptor portion tries to, a far superior method would be to show say ten different possibilities for a few species in quick succession. Changing colors and adding wattles wouldn't be that resource intensitive and would get the idea across to laymen without making it seem like we know they had definite soft features and patterns (I'm guessing the Yixian pigments were unknown when this was made). The Cryolophosaurus portion taught us about the factual behavior... of lions. The mosasaur segment taught us... er... "a mother's protective instinct is a force of nature than can change the world." And the Glacialisaurus one taught us "a little bad luck goes a long way." That's certainly scientific. Maybe the next episode will teach us "the disadvantaged underdog can succeed with perseverance and faith in himself." Sigh

To sum up, watch if you like largely accurate-looking dinosaurs acting like humans in zany situations and learning valuable life lessons. If you want a show that clearly indicates which parts are based on paleontology, shows dinosaurs as they may have been, and teaches you something about them, keep dreaming.

Tehuelchesaurus and how to describe the affinities of a taxon

2011-09-09T18:46:00.000-07:00

I've often complained about the tendency for authors to view their most parsimonious cladogram as "the right" tree, such as here and here. I note that it's usually more helpful to describe how parsimonious different hypotheses are, since while new analyses usually change the topology somewhat, they rarely support relationships that were strongly rejected before. Carballido et al. (2011) recently redescribed the sauropod Tehuelchesaurus, and in addition to a detailed osteology and several other important discussions, their paper contains a phylogenetic analysis that did things just the way they should. The analysis (249 characters, 45 taxa) is based on Wilson's (2002) analysis with added data, including numerous newly added macronarians. Some characters were ordered, taxa which cause polytomies were deleted a posteriori, and Tehuelchesaurus emerged as a basal camarasauromorph sister to Galveosaurus, not a relative of Omeisaurus as originally thought by Rich et al. (1999). But instead of simply letting the matter rest there, Carballido et al. included the section "Testing Alternative Positions for Tehuelchesaurus." Music to my ears. They tested not only the Omeisaurus alternative (9 steps longer), but also positions slightly more (1 step longer) and less (2 steps longer) than Galveosaurus, and noted the character support for all of these. In addition, the authors wrote the following which basically covers any plausible position-

"Other positions within basal camarasauromorphs (in any position within the Janenschia/Tastavinsaurus clade, as sister taxon to Europasaurus, more basal than Europasaurus, and as sister taxon to Camarasaurus) and as a macronarian outside Camarasauromorpha, but more derived than Haplocanthosaurus, require three additional steps. Placing Tehuelchesaurus as sister taxon of Haplocanthosaurus results in a suboptimal tree four steps longer than the MPTs, and as the most basal macronarian needs even five additional steps. Even more steps are required to place this taxon in the Titanosauriformes (seven additional steps as a basal somphospondyl and eight additional steps as a basal brachiosaurid).

Any position outside Macronaria also results in considerably suboptimal tree lengths. Five additional steps are needed to make Tehuelchesaurus the most basal diplodocoid, but any position within higher diplodocoids results in trees that are at least ten steps longer than the MPTs. Likewise, placing Tehuelchesaurus outside Neosauropoda requires six additional steps, and any placement among basal, nonneosauropodan taxa results in trees at least nine steps longer than the MPTs. Thus, the possibility of a Jurassic Patagonian clade of sauropods, including Patagosaurus and Tehuelchesaurus, can also be rejected, as it requires 12 additional steps."

The paper succeeds in giving you a much clearer idea of Tehuelchesaurus' relationships than any one cladogram could. Anybody describing a new taxon should follow their example.

Carballido, Rauhut, Pol and Salgado, 2011. Osteology and phylogenetic relationships of Tehuelchesaurus benitezii (Dinosauria, Sauropoda) from the Upper Jurassic of Patagonia. Zoological Journal of the Linnean Society. DOI: 10.1111/j.1096-3642.2011.00723.x

Do we have dromaeosaurid evolution backwards?

2011-08-17T21:18:00.000-07:00

The basic evolution of Maniraptora has seemed pretty well established in the past decade, thanks to TWG papers describing Sinovenator, Mei, Mahakala, Xiaotingia and such. The basal paravian was a little bird-like taxon, like Microraptor on the dromaeosaurid end or Jinfengopteryx on the troodontid end, with genera like Rahonavis and Anchiornis breaking the boundaries even more. Going further towards the base of Maniraptora, the cranial similarities between scansoriopterygids and basal oviraptorosaurs have suggested a short-snouted herbivorous ancestor, while Shuvuuia and Pelecanimimus have similar skulls that suggest the first maniraptoriform was not a macropredator. Large, more obviously carnivorous taxa like eudromaeosaurs are seen as reversals to a more traditional theropod lifestyle. It's a nice story and may be right, but what if it's wrong?

Dromaeosaurid morphology forms a continuum from the extreme of Achillobator with its deep snout, mesially serrated teeth, low DSDI, rather short coracoid, posteriorly facing glenoid, relatively short arms, deep brevis fossa, large anterior pubic boot and proximally placed obturator process, though Deinonychus, Velociraptor, Bambiraptor, Sinornithosaurus, Microraptor, Buitreraptor/Unenlagia and ending at Rahonavis. Even if the unenlagiines are avialans though, dromaeosaurids need a lot of reversals no matter which direction evolution went. Note that stratigraphy doesn't strongly support either option. We have Utahraptor from the Barremian which is very similar to Achillobator, and dromaeosaurid-like teeth with mesial serrations resembling both dromaeosaurines and velociraptorines in the Late Jurassic. Then again, there's the microraptorian-like Graciliraptor and Shanag which also lived early, and the possible microraptorian "Paleopteryx" from the Morrison.

There's also a possible transitional form between basal coelurosaurs and dromaeosaurids- Ornitholestes. Like dromaeosaurids, Ornitholestes has a third premaxillary tooth much smaller than the first two, short cervical vertebrae with tall neural spines, prominent anterior cervical epipophyses, a crest-like ventral tuberosity on the humerus, an enlarged second pedal ungual and a transversely expanded metatarsal IV. It's also similar to paravians in the elongate distal caudals and bifurcated chevrons. Deriving dromaeosaurids from something of Ornitholestes-grade would explain why they are almost unique among derived maniraptorans in having prefrontals, which unlike the dental characters of eudromaeosaurs, are not plausibly due to macropredatory habits. In this scenario, microraptorians would be convergent with birds in their aerial characters.

Is there any other evidence for this idea? Don't troodontids show the same pattern as dromaeosaurids, going from Jinfengopteryx/Anchiornis to Mei/Sinovenator to Sinornithoides/Byronosaurus to Troodon? Maybe not. Jinfengopteryx and Anchiornis can switch to Avialae easily, and the same may be true for Mei and Sinovenator. They're often avialans in the in progress Lori matrix, even with Xu et al.'s troodontid characters. Lori itself emerged sister to Sinornithoides in Hartman et al.'s SVP poster and is Jurassic in age, with serrated teeth. Maybe that's the basal grade for troodontids, and birds are related but evolved serrationless teeth, long arms, dorsal ischial processes and such on their own branch.

The Jurassic Haplocheirus also supports this idea, since it shows serrated teeth and a general morphology so primitive that Cau's Sumrukia matrix found it to clade with compsognathids. Note therizinosaurs also have mesial and distal serrations, and that Falcarius has made the clade more basal in most matrices, unlike earlier ideas they were related to oviraptorosaurs. Maybe coelurosaurs were of the compsognathid-coelurid grade all through their evolution, with ornithomimosaurs, alvarezsaurids, therizinosaurs, dromaeosaurids and troodontids+birds each developing their birdlike and/or herbivorous characters separately. This idea is kind of anti-Paulian or anti-BCF in nature and has plenty of precedent in the literature. Ostrom long suggested Ornitholestes as a dromaeosaurid ancestor, and Makovicky (1995) found the two to be sister taxa to the exclusion of birds based on vertebral characters.

Of course the real test is with cladistic analyses, so how does the idea fare? The in progress Lori matrix finds a fairly traditional tree with Ornitholestes sister to Maniraptoriformes, microraptorians and Unenlagia basal among dromaeosaurids, and is somewhat unusual in finding troodontids sister to birds. Constraining Ornitholestes to be a dromaeosaurid and the dromaeosaurid topology 'backwards' from the consensus (Achillobator,Dromaeosaurus(Deinonychus,Velociraptor(Microraptor,Sinornithosaurus))) results in trees 11 steps longer. Not too bad when you consider enforcing Longrich and Currie's (2009) plausible-seeming traditional dromaeosaurid topology is 7 steps longer than the minimum.

And the best paper written about a theropod is...

2011-08-09T02:14:00.000-07:00

I'm sure I can come across as a grumpy old carmudgeon thanks to my frequent criticisms of papers, even good ones like Benson et al. (2011). Critiquing is fun and I think more important than praise when it comes to scientific papers, but for a change, here's a paper I was floored by.

I was lucky enough to be sent a copy of Dal Sasso and Maganuco's new Scipionyx monograph, and boy does it deliver! Scipionyx is one of those Science/Nature taxa that's initially described in two pages with a couple figures, then goes for years until a decent description comes out (See how I work criticism into even an article designed to praise, heh. Btw, of that list, Enantiornis has since been redescribed, and papers on Guanlong, Buitreraptor and Haplocheirus are in the works. Woo!) Luckily, the illustrations in Dal Sasso and Signore's 1998 paper were superb and covered all the material, so waiting wasn't as painful as it is for some other taxa. Even so, if every 'tabloid taxon' were given this good of a treatment once they were redescribed, I'd have no complaint waiting a decade for them. The monograph is simply unparalleled in every aspect. Quality diagnosis of autapomorphies. Huge illustrations and color photos, extensive explanatory diagrams, x-rays, ultraviolet, different angles. Measurements of everything. Eleven pages discussing the ontogenetic indicators. A phylogenetic analysis using a good base (Senter's TWG modification), codes taxa completely, has explicit coding changes based on new papers and most relevent taxa included (exceptions are Proceratosaurus and Bagaraatan). Then there's the long description of all the soft parts most taxa don't leave us. And the taphonomy. And the physiology, discussing Ruben's terrible ideas. And the quality reconstructions. And the discussion of diet, given its multiple prey remains. The tome ends with several life restorations, of which my favorite is Riboli's. See, that's why I don't write more glowing reviews- saying "x is good, y is good, etc." just gets repetitive and uninteresting. Sort of like how ancient theologians said much more about the tortures of Hell than the joys of Heaven. ;)

As for negatives, Scipionyx and Orkoraptor are grouped together based on the supposed caudal pleurocoels of the former. Yet those are so small they look more like nutrient foramina to me, which have caused similar confusion in Acrocanthosaurus and some therizinosauroids. But Dal Sasso and Maganuco correctly discuss how the Senter matrix does not include relevent taxa and characters from Benson et al.'s study, and that the latter does not include enough coelurosaur information. Also, I would disagree with a couple coding choices for ontogenetically variable characters in Scipionyx, which are discussed in Appendix 5. But hey, what other papers even mention why they code ontogenetically variable characters in young specimens? So really, even the few problems were elaborated on to the point that I can't count them against the authors. The work is simply a masterpiece.

Anyone who wants to write a description of a theropod, look at what Dal Sasso and Maganuco created, and copy its format and scope to the best of your ability.

Dal Sasso and Maganuco, 2011. Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy: Osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy, and palaeobiology. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 281 pp.

Pneumatic disappointment

2011-08-06T18:34:00.000-07:00

Benson et al. have a new paper out on theropod postcranial pneumaticity which I was extremely excited about, but the paper itself came as quite the disappointment. Not the general conclusions, which I agree with, but the data collection. The abstract reads "We review recent work on the significance of pneumaticity for understanding the biology of extinct ornithodirans, and present detailed new data on the proportion of the skeleton that was pneumatised in 131 non-avian theropods and Archaeopteryx." With supposed pneumatic ilia in Piatnitzkysaurus and others, Buitreraptor's pneumatic furcula, Shixinggia's pneumatic femur and other recent records, examining 131 theropods for postcranial pneumaticity would be quite enlightening. It's one of those features that is easily missed unless looked for, not often described, and rarely apparent in photos or illustrations. This is especially true for coelurosaurs, since most of the reported unusual pneumatic bones have been from them. All of the authors (Benson, Butler, Carrano and O'Connor) have done excellent detailed work before, so my expectations were high.

The meat of the paper is appendix S1, which contains all of the primary data. It's available here for those who are interested. The first problem is that it's all axial, so there goes my hope of getting some real info on how common appendicular pneumaticity is. More disappointing though is that only 12 of the 99 coelurosaurs are coded from seeing real specimens. The rest is all from the literature. Not that I'm one to frown on using literature, since that's where much of my data comes from too. And Benson et al. are usually good at determining which data can be coded from the literature and noting when information is from a figure, data matrix, etc.. But the information is basically what I could (and have) accumulated myself, with a few new additions thanks to personal communications with Balanoff and Brusatte, but then again I have my own sets of unpublished photos and AMNH observations with data not used by Benson et al.. I suppose I should be happy since this backs up my thesis that papers covering many taxa usually rely mostly on the literature and that my own upcoming paper explicitly describing codings in coelurosaurs is comparable in this measure to one written by four professional leaders in the field. But this time I was hoping for something more, akin to what Nesbitt et al. (2009) did for theropod furculae.

Benson, Butler, Carrano and O'Connor, 2011. Air-filled postcranial bones in theropod dinosaurs: Physiological implications and the 'reptile'-bird transition. Biological Reviews. DOI: 10.1111/j.1469-185X.2011.00190.x

Epichirostenotes and how it changes coding

2011-07-26T16:49:00.000-07:00

Sullivan et al. (2011) just named two new caenagnathids, Ojoraptorsaurus boerei for a partial pubis and Epichirostenotes curriei for ROM 43250, a specimen from the Horseshoe Canyon Formation described as Chirostenotes by Sues (1997). Jaime Headden wrote a great post on the situation here and I agree with his assessment. I'm extremely doubtful Ojoraptorsaurus can be diagnosed, given the large amount of interspecific variation in most theropods and the low number of comparable caenagnathids. But that's not too important considering it's just a partial pubis. My main concern here is a more practical one about Epichirostenotes.

Ischia previously referred to Chirostenotes (from Sues, 1997). A- RTMP 79.20.1, which is still placed in Chirostenotes pergracilis. B- ROM 43250, now the holotype of Epichirostenotes curriei. The only other shared elements are ilial fragments and a sacrum for which no differences have been noted.

How should we now code Chirostenotes? The genus has been used in many analyses, including the Theropod Working Group matrix, which I've been correcting for the description of a new paravian. In that matrix, it is apparently based on a combination of the Chirostenotes, Macrophalangia and Caenagnathus holotypes, as well as partial skeletons RTMP 79.20.1 (Currie and Russell, 1988) and ROM 43250. It wouldn't be too important, except ROM 43250 is our only described source for coding Chirostenotes' maxilla, braincase, cervicals, dorsals, caudals and pubis. So if we leave it out, we're losing a lot of information. And without a more complete caenagnathid to code, and few overlapping elements, there's a large chance it won't group with Chirostenotes, so could harm oviraptorosaur topology (like coding Caenagnathus separately did for Senter, 2007). But combining it with Chirostenotes could be misleading once Elmisaurus and Hagryphus are added, since nothing argues ROM 43250 isn't closer to these latter genera. While ROM 43250 isn't comparable to either, a second specimen from the same formation (metatarsal II CMN 9570, unmentioned by Sullivan et al.) is distinctive from Elmisaurus due to its lack of fusion and straight distal end. These are plesiomorphies though, so do not argue strongly for its referral to Chirostenotes. And the metatarsal isn't comparable to ROM 43250 anyway, so any referral to Epichirostenotes is based purely on size and provenence. But nothing argues the Horseshoe Canyon specimens aren't Chirostenotes either, since so far the apomorphies of Chirostenotes are only known from the mandible (assuming Caenagnathus collinsi is properly synonymized) and other parts of the metatarsus. The minor differences between the ischia of Epichirostenotes and RTMP 79.20.1 are just like those found between individuals of Tyrannosaurus rex, Microraptor zhaoianus and other species. The distinction boils down to size (which could easily be ontogenetic) and provenence. Now this doesn't make Epichirostenotes a nomen dubium, because the braincase and maxilla are certainly distinct from comparable named theropods, it's just that no other named caenagnathid can be compared for the most part.


Tyrannosaurus rex ischia to show interspecific variation. Left- FMNH PR2081 left and right (from Brochu, 2003); Right top- CM 9380 (from Osborn, 1906); Right bottom- AMNH 5027 (from Osborn, 1916).

Note how the Tyrannosaurus ischial variation mirrors that between Chirostenotes and Epichirostenotes. The latter's ischial diagnosis is-
1. "Ischium long and expanded posteriorly; broad behind obturator process." There is no known comparative length difference, since Epichirostenotes doesn't preserve an ilium and Chirostenotes doesn't preserve a pubis. The posterior expansion and breadth posterior to the obturator process refers to the greater depth in Epichirostenotes. As seen most distinctly between the upper right and lower left pictures above.
2. "obturator process expanded and triangular." This refers to the greater depth of the obturator process and non-rectangular tip in Epichirostenotes. As seen between the two left pictures above.
3. "having a prominent anterior proximal hook-like projection." This refers to the pubic peduncle being longer and more ventrally projecting in Epichirostenotes, enclosing the obturator notch more. Note the two right pictures above also differ in the length and angle of the ventral portion of the pubic peduncle.
Also notice the other differences within Tyrannosaurus. The lower right pic has a narrower body proximal to the obturator process. It also has a longer and more rounded proximodorsal process. The two right pics have curved shafts compared to those on the left.

So it's a very awkward situation. I'd bet curriei really is a distinct species from pergracilis, if only because that seems to be true for other theropods compared between those formations (though the published evidence for this is usually as tenuous as the current case). But the known remains don't justify that anatomically, and whether curriei is more closely related to Chirostenotes than Elmisaurus or Hagryphus is basically unknowable. If it is closer to pergracilis, then I could see only the most extreme splitter keeping them as separate species based on known remains, let alone genera. Maybe CM 78000 and 78001 will help sort things out, and it would have been prudent to wait until Sues and Lamanna finish describing them before dealing with the taxonomy of ROM 43250. I think for now I'll just call ROM 43250 Chirostenotes? curriei and keep the Chirostenotes OTU intact that way. There's no evidence against it at least, even though it's not necessarily true. And it's not unheard of for other taxa in the matrix. The Struthiomimus OTU has always included both the Dinosaur Park S. altus and the unnamed Horseshoe Canyon species represented by AMNH 5257 and exceptionally complete RTMP 90.26.1. If someone were to name the latter "Epistruthiomimus unnecessari" based on Longrich's comment the metacarpus is more slender, would we have to break up our Struthiomimus OTU? Note that like the caenagnathid situation, the described differences between species are few and of debatable significance, while there has been no study showing they form a monophyletic group based on apomorphies. So the facts are the same, but the new genus for ROM 43250 just complicates matters.

Testing Harding's idea- Constraining topologies based on adding taxa in stratigraphic order

2011-07-15T18:47:00.000-07:00

On the DML, Grant Harding proposed an idea. Run cladistic analyses using only the earliest taxa, then sequentially add later taxa, but each time constrain the topology to match the trees found using only earlier taxa. I tried it using my corrected TWG matrix, which at the moment covers all the taxa and characters up to Hwang et al. (2004).

So for example, the first run included only Jurassic taxa- Sinraptor, Allosaurus, Ornitholestes, Compsognathus and Archaeopteryx. The tree found was (Sinraptor,Allosaurus(Ornitholestes(Compsognathus,Archaeopteryx))), which is standard. It disagrees with the total data tree in having Ornitholestes and Compsognathus switched, presumably because of the lack of ornithomimosaurs, therizinosaurs, other compsognathids, etc.. If this were a more complete analysis, you'd have Haplocheirus, scansoriopterygids, Pedopenna, Lori and Anchiornis there as well as all the non-maniraptoriform Jurassic coelurosaurs.

I then added the taxa which lived slightly later- Shenzhousaurus, Incisivosaurus and Sinovenator. I constrained the analyses to only find trees agreeing with the relationships found using the Jurassic taxa. This resulted in- (Sinraptor,Allosaurus(Ornitholestes(Compsognathus(Shenzhousaurus(Incisivosaurus(Sinovenator,Archaeopteryx)))))). This matches the total tree besides the point noted above. Again, a more complete analysis would have Dilong, Kinnareemimus, Nqwebasaurus, Graciliraptor, Mei, Sinusonasus, "Eoconfuciusornis" and maybe a few other birds.

In any case, I added the following groups next-
- Harpymimus, Pelecanimimus.
- Utahraptor.
- Caudipteryx, Confuciusornis, Sinornithosaurus, Huaxiagnathus, Sinosauropteryx.
- Deinonychus, Microvenator, Sinornithoides, Alxasaurus, Microraptor, IGM 100/44.
- Garudimimus, Segnosaurus, Erlikosaurus, Achillobator.

Then I hit a snag. The next group was Patagonykus, Unenlagia comahuensis and U? paynemili. None of these taxa has a definite position in the cladogram when constrained to match the topology of the previous taxa. The Unenlagia species are both some kind of paravian, while Patagonykus is at least as derived as compsognathids, but is not an ornithomimosaur, therizinosaur, avialan or eudromaeosaur. And there's no way to constrain a tree to include uncertain relationships like these. The only taxon left to include before the big end Campanian-Maastrichtian group was Alvarezsaurus, but it didn't help, since it emerges as a compsognathid-grade taxon without affecting Patagonykus' relationships. So that's a problem with this kind of analysis. The same is true of the many early fragments that show character combinations unique to certain clades (e.g. Jurassic dromaeosaurid teeth with high DSDIs). These are normally useless to include in analyses since they don't have different codings than more complete later specimens, but in this variety of analysis, they'd be potentially useful early on but would form polytomies later if not deleted.

Another issue is that many taxa have unconstrained ages, and adding these in order of their earliest possible age, mean age, etc. is going to likely change the results.

To get a finished result of sorts, I simply did not constrain the position of Patagonykus, Unenlagia or U? paynemili in the final run with Campanian-Masstrichtian taxa, since they come out somewhere within their polytomies in the total data analysis anyway, though I did still force Alvarezsaurus to be compsognathid-grade. The end result was a tree 19 steps longer than the unconstrained tree. The primary differences are-

- Alvarezsaurus is by compsognathids due to its position before parvicursorines were added.
- Ornitholestes (thanks to the Jurassic analysis), therizinosaurs (thanks to Alxasaurus when analyzed with basal ornithomimosaurs) and Patagonykus+parvicursorines (probably due to following therizinosaurs) are outside Maniraptoriformes.
- Pelecanimimus is an ornithomimosaur due to alvarezsaurids not being included until after it was added.
- Microvenator is a basal maniraptoran due to the absence of more complete caenagnathoids until later runs.
- Caudipteryx is an oviraptorosaur thanks to clading with Incisivosaurus early on.
- Troodontids are paraphyletic to dromaeosaurids instead of to birds (except that Sinovenator is still an avialan), and Microraptor is a basal dromaeosaurid instead of a basal avialan.

So some results are closer to the consensus while others aren't. I suppose the real test will be to see if any of these relationships are found when I add more taxa and characters to the complete analysis.

Rieppel's reptile matrix and the turtle problem

2011-06-28T16:54:00.000-07:00

Which group turtles are most closely related to is one of the greatest problems in vertebrate paleontology. Traditionally parareptiles, deBraga and Rieppel (1997) and variations on that matrix find them to be close to Sauropterygia in Lepidosauromorpha, while molecular analyses find them to be archosauromorphs. Recently, Lyson et al. (2010) added Proganochelys and Eunotosaurus to the Rieppel matrix, along with six characters they share, and found turtles now clade with it inside Parareptilia instead. What Lyson et al. don't mention is that diapsid turtles are only seven steps longer. Not much of a difference, but it's something, right? I'm not so sure. Looking at the characters, there are huge problems. I give Peters a lot of (deserved) flack for the poorly designed characters in his amniote analysis, but this honestly isn't any better. Let's examine some problems...

Composite Characters
Many characters describe more than one variable in morphology, which is not useful. These can have states describing different variables (e.g. teeth serrated vs. teeth large) or multiple variables described in a single state (e.g. teeth large and serrated vs. teeth small and unserrated). A common variant is to have "x feature absent" as a state of a character which otherwise describes different morphologies (e.g. teeth serrated vs. teeth unserrated vs. teeth absent). The only way an absent state should be in a character that's not simply "absent vs. present" is if the variable is number (e.g. two centrales vs. one centrale vs. no centrale) or size (e.g. quadratojugal large vs. quadratojugal small vs. quadratojugal absent). Characters with this issue are-

1. Premaxilla exposure: exposure anterolateral to external nares small restricted to low posterolateral process forming less than one-half the height of the premaxilla (0); posterolateral process tall reaching dorsal process (1).
6. External nares exposure: dorsal process of premaxilla broad restricting nares to a lateral exposure (0); dorsal process narrow resulting in dorsal exposure of nares (1).
8. Choana palatal exposure: parallel medial border of maxilla (0); deflected posteromedially (1); hidden in palatal view (2).
17. Lacrimal morphology: present and contributing to exteral nares (0); present at least as long as tall, but excluded from external nares (1); if present snall[sic], restricted to orbital margin, or absent entirely (2).
30. Postorbital/supratemporal relationship: in contact (0); not in contact (1); supratemporal absent (1).
38. Quadrate excavation: absent along posterior edge (0); posterior edge deeply excavated forming a concave region (1); quadrate greatly reduced (2).
42. Quadratojugal morphology: present and horizontal dimension exceeds vertical dimension by a factor of at least three (0); present but vertical dimension exceeds horizontal by a factor of at least two (1); present, but greatly reduced and restricted to condylar region (2); absent (3).
49. Pineal foramen position: located in the middle of the body from the parietal (0); displaced posteriorly (1); displaced anteriorly (2); absent (3).
51. Lower temporal fenestra: absent (0); present quadratojugal included (1); present quadratojugal excluded (2); open ventrally (3).
52. Postparietal: present and paired (0); present but fused (1); absent (2).
60. Orientation of paroccipital process: extends laterally forming 90° with parasaggital plane (0); paroccipital process deflected posterolaterally at an angle of about 20° from the transverse width of the skull (1); paroccipital process deflected dorsolaterally at an angle of nearly 45° (2).
65. Ventral braincase tubera: absent (0); present and restricted to basioccipital (1); present, very large, and restricted to basisphenoid (2).
73. Interpterygoid vacuity: anterior end tapers sharply (0); anterior border cresentric (1); absent (2).
74. Suborbital fenestra: absent (0); present but with contribution from either maxilla or jugal along lateral border (1); present, but with both maxilla and jugal excluded from lateral border (2).
75. Cultriform process: long, exceeding length of parasphenoid body and reaching forward to the level of the posterior limit of the internal nares (0); short, not reaching the level of the internal nares (1).
81. Ectopterygoid: present and edentulous (0); present and dentigerous (1); absent replaced by medial process of jugal (2); absent replaced by lateral process of pterygoid (3).
83. Coronoid process: absent (0); present formed by coronoid (1); present formed by dentary (2).
94. Tooth implantation: set in deep sockets ( ); loosely attached to medial surface of jaw (1); ankylosed to jaw (2).
100. Vertebral central articulations: amphicoelous (0); platycoelous (1); other (2).
106. Trunk neural arches: swollen with heavy zygapophyseal butress (0); narrow, strongly excavated neural arch with no heavy butress (1); swollen, but with narrow tall zygapophyseal butress (2).
118. Acromion process: absent (0); present, blade-like, parallelogram in lateral aspect, and arising from the lateral edge of the scapula (1); present, triangular in lateral aspect, and arising from ventromedial border of scapula (2).
126. Supinator process: large angled away from humeral shaft (0); large confluent with shaft (1); small or absent (2).
136. Pubic tubercle: if present small and directed anteroventrally (0); large and strongly turned ventrally (1).
139. Femoral shaft: short and stout (0); sigmoidally curved and slender (1).
141. Femoral trochanter major: absent (0); present and deflected distally from the proximal head of the femur (0); pyramidal in shape and nearly in line with the head of the femur (2); similar in shape to state (1) but positioned at mid-shaft length (3).
149. Astragalus/calcaneum relationship in adult: never fused (0); fused (1); hinge present (2).
159. Fifth pedal digit: longer than first digit (0); shorter and more lightly built than first (1).

Lyson et al.'s new character 176 is also a composite-

176. Dermal skull tuberosities: absent (0); tuberosities present (1); tuberosities and pits present (2); honeycomb texture present (3).

Unordered Characters
All characters were ran unordered, but some kinds of characters need to be ordered, when one state is intermediate. Sometimes the intermediate state isn't placed between the others, which means the states have to be switched and recoded in the matrix for the ordering to work. Other times, some of the states should be ordered, but others don't belong in the same character since they describe different variables (as noted above). These can only be fixed by dividing the character. Characters with this issue are-

19. Skull proportions: preorbital skull length equal to postorbital length (0); preorbital length exceeds postorbital skull length (1); postorbital length exceeds preorbital skull length (2).
35. Squamosal lateral exposure: ventral process long, descends to level limit of orbital margin (0); ventral process short, terminates prior to reaching ventral orbital margin (1); ventral process absent or restricted to region above dorsal limit of orbit (2).
42. Quadratojugal morphology: present and horizontal dimension exceeds vertical dimension by a factor of at least three (0); present but vertical dimension exceeds horizontal by a factor of at least two (1); present, but greatly reduced and restricted to condylar region (2); absent (3).
47. Parietal skull table: broad with the mid-line, transverse, width not less than half of the length measured along the element’s midline (0); constricted with the length exceeding the width by at least three times (1); forming saggital crest (2).
49. Pineal foramen position: located in the middle of the body from the parietal (0); displaced posteriorly (1); displaced anteriorly (2); absent (3).
53. Supratemporal: present and large with its transverse dimension nearly equal to its parasaggital dimension (0); present but reduced so that its transverse dimension is less than half of its parasaggital dimension (1); absent (2).
55. Tabular: present but restricted to dorsal region of occiput (0); present but ventrally elongate descending to lvel[sic] of occipital condyle (1); absent (2).
59. Posttemporal fenestra: absent (0); present but diameter less than half of the diameter of the foramen magnum (1); large posttemporal fenestra with a diameter at least eqqual[sic] to that of the foramen magnum (2).
76. Palatal process of pterygoid: extends anterior to the anterior limit of the palatine (0); forms oblique suture with palatine but process ends before reaching anterior limit of palatine (1); forms transverse suture with palatine (2).
78. Dentition on transverse flange: present as a shagreen of teeth (0); present but with one large distinct row of teeth along the posterior edge of the transverse flange (1); edentulous (2).
82. Mandibular joint: even with occiput (0); behind occiput (1); anterior to occiput (2).
88. Splenial: enters mandibular symphysis (0); present but excluded from mandibular symphysis (1); entirely absent (2).
89. Angular lateral exposure: exposed along 1/3 the lateral face of the mandible (0); exposed only as a small sliver along the lateral face (1); absent from lateral aspect (2).
100. Vertebral central articulations: amphicoelous (0); platycoelous (1); other (2).
115. Interclavicle: anterior end rhomboidal (0); T-shaped but with broad transverse bar with its anteroposterior dimension at least 1/4 the transverse width of the bar (1); T-shaped but transverse bar slender with its anteroposterior dimension much less than 1/4 the transverse width (2).
117. Scapula: short and broad with its height not exceeding its width (measured at the level of the glenoid) by more than three times (0); tall and blade-like with its height exceeding the width by at least a factor of four (1); tall and slender nearly cylindrical in cross-section (2).
126. Supinator process: large angled away from humeral shaft (0); large confluent with shaft (1); small or absent (2).
129. Radius/ulna ratio: radius shorter than ulna (0); radius longer than ulna (1); radius and ulna subequal (2).
142. Intertrochanteric fossa: well defined (0); reduced (1); absent (2).
150. Astragalus/distal tarsal IV articularion: articulation poorly defined (0); articulation well defined (1); articulation absent (2).
158. Number of pedal centralia: both lateral and medial centralia present (0); medial pedal centralia lost (1); both centralia lost (2).
161. Pedal phalangeal formula: 2, 3, 4, 5(4), 4 (0); 2, 3, 4, 4, 3 (1); 2, 3, 3, 4, 3 or less (2).
165. Body osteoderms: absent (0); present but few restricted to mid-line (1); present but spread all over back (2).
166. Osteodermal ridges: absent (0); fine regular spaced ridges (2); heavy irregularly spaced ridges (3).

Lyson et al.'s new character 176 also has states that should be ordered once it is divided into 2 separate characters-

176. Dermal skull tuberosities: absent (0); tuberosities present (1); tuberosities and pits present (2); honeycomb texture present (3).

Characters Which Do Not Cover All Possibilities
The character states must combine to cover the possible range of morphologies, but sometimes gaps are left between them, which makes coding taxa within that gap problematic. Examples of this are-

20. Prefrontal/palatine antorbital contact: narrow forming less than 1/3 the transverse distance between the orbits (0); contact broad forming at least 1/2 the distance between the orbits (1).
26. Frontal proportions: length exceeds width by at least four times (0); length no greater than twice the width (1).
27. Frontal morphology: parallelogram shaped (0); hour-glass shaped (1).
42. Quadratojugal morphology: present and horizontal dimension exceeds vertical dimension by a factor of at least three (0); present but vertical dimension exceeds horizontal by a factor of at least two (1); present, but greatly reduced and restricted to condylar region (2); absent (3).
45. Stapes morphology: robust with its greatest depth exceeding one-third of its total length (0); slender with the length at least four times the depth (1).
47. Parietal skull table: broad with the mid-line, transverse, width not less than half of the length measured along the element’s midline (0); constricted with the length exceeding the width by at least three times (1); forming saggital crest (2).
59. Posttemporal fenestra: absent (0); present but diameter less than half of the diameter of the foramen magnum (1); large posttemporal fenestra with a diameter at least eqqual[sic] to that of the foramen magnum (2).
61. Paroccipital process morphology: slender with anteroposterior dimension not exceeding dorsoventral dimension (0); heavy with anteroposterior dimension at least 1/3 greater than dorsoventral dimension (1).
64. Basi/parasphenoid ratio: narrowest transverse width no more than 60% of the maximum length measured from basipterygoid process to posteriomost limit (0); narrowest part (waist) exceeds 80% of the length (1).
114. Clavicle: interclavicular process of clavicle broad and blade-like with the maximum anteroposterior length at least 1/3 of its transverse dimension (0); slender with its anteroposterior length less than 1/5 of the transverse dimension (1).
124. Humeral shaft/distal end ratio: shaft length less than 1/3 the maximum width of the distal end of the humerus (0); shaft long at least four times the width of the distal end (1).
154. Metatarsal V: long and slender with length exceeding the width of the base by at least three times (0); short and broad with base width equivalent to at least twice the length of the element measured along its midline (1).

Poorly Defined Characters
These are too numerous to mention, but many characters lack a quantification. Some are especially bad, like "Limbs: short and stout (0); long and slender (1)."

The latter two kinds of characters don't really affect the matrix, they just make coding new taxa problematic since you could have a different concept of "stout" or "large" or how curved or angled something has to be to count. Who knows if Li et al.'s coding of Odontochelys or Lyson et al.'s coding of Proganochelys and Eunotosaurus used the same concepts as deBraga and Rieppel's original codings? Even considering only the first two kinds of character errors though, 47 of the 168 characters are affected. That's 28%.

Ordering the (non-composite) characters is easy enough. After deleting Testudines (since Proganochelys was used as a major source, and is now its own OTU), it takes 7 more steps to place turtles in Diapsida in Lyson et al.'s original matrix. After proper ordering, the topology is the same except kuehneosaurs are now sister to a clade of lepidosaurs and sauropterygians instead of in a trictomy with both groups. It now takes 8 more steps for diapsid turtles. After proper ordering and deleting the composite characters, the consensus tree differs in that Macroleter is closer to derived parareptiles than lanthanosuchids and Acleistorhinus, and Sauria breaks down except for Trilophosaurus+Rhynchosauria and sauropterygians, with prolacertiforms oddly basal. It now only takes three steps to place turtles in Diapsida though. In all of these analyses, they are sister to sauropterygians when in Diapsida.

Factor in the small number of characters and taxa, and my conclusion is that amniote matrices aren't good enough to tell us much about turtle relationships yet.

Qiliania a confuciusornithid?

2011-06-26T05:42:00.000-07:00

Another quiet month due to working on publishable projects, but here's something I noticed when getting an update for my site ready.

Ji et al. (2011) described the new bird taxon Qiliania, based on a pelvis and hindlimbs. They included it in O'Connor et al.'s Shanweinao matrix, along with three unnamed Xiagou enantiornithines, Soroavisaurus and Archaeorhynchus. It emerged as an enantiornithine, which is what the authors describe it as. But then there's this statement- "DNHM D2522 (the holotype of Rapaxavis pani; Morschhauser et al., 2009) and PKUP-V1069 (the holotype of the basal ornithuromorph Longicrusavis houi; O’Connor, Gao & Chiappe, 2010) were removed (see Supporting Information)."

Well that's weird. Why would you remove those two taxa? Unfortunately, the supplementary information just lists tree descriptions and gives the codings for the added taxa. They're the only undescribed taxa from O'Connor et al.'s Shanweinao matrix, but O'Connor is an author of Qiliania too. O'Connor was first author of the Longicrusavis description, which was submitted almost a year before the Qiliania paper was submitted. The Rapaxavis description came out two months before the Qiliania paper was submitted. So I can't see any reason the Qiliania authors wouldn't trust the codings and have the resources to check them.

In any case, the interesting point is that when Rapaxavis and Longicrusavis are left in, the cladogram is different. Confuciusornithids, 'Jeholornis' (= Shenzhouraptor) and Sapeornis now form successively more distant outgroups to Ornithothoraces. Zhongornis is a confuciusornithid as I proposed. Relationships in Enantiornithes are almost completely different, with all the CAGS specimens avisaurids, a clade of Las Hoyas taxa with Eoenantiornis sister to it and a Gobipteryx+Vescornis clade. In Ornithuromorpha, hongshanornithids and songlingornithids are sister taxa. But most important for a paper on Qiliania, that genus is now a confuciusornithid.

This is based on the short ischium, posteriorly excavated tarsometatarsus (also in avisaurids) and J-shaped metatarsal I (also in some enantiornithines). Forcing it to be an enantiornithine is only one step longer (which rearranges enant topology again), so I'm not arguing Ji et al. were wrong to place it in that clade, but I do wonder why they excluded taxa which were already coded. At the least, this shows the importance of including taxa in analyses and suggests Qiliania may be better placed as Pygostylia incertae sedis.

Incidentally, O'Connor et al.'s matrix is also the one Kurochkin et al. (2011) used for their Mystiornis paper. They added Anchiornis, Mei, Avisaurus, Vorona and Mystiornis and found the latter four formed a clade one node closer to Aves than Archaeopteryx. With Anchiornis being in a polytomy with this clade and more derived birds, this suggests a systematic coding error by the authors for their added taxa, which can unfortunately not be confirmed since the matrix was not published. I added Mystiornis, Avisaurus and Vorona myself and found the latter two fall out in their normal positions (derived enantiornithine and basal ornithuromorph), while Mystiornis is an ornithothoracine outside of Longipterygidae and Hongshanornis+Aves. When these taxa and Ji et al.'s taxa are all ran together, Mystiornis is sister to Avisauridae (similar to Cau's Megamatrix) and Qiliania stays as a confuciusornithid.

Theropod Working Group matrix recoded

2011-06-07T20:27:00.000-07:00

The result of recoding all the taxa is-

Notice there are a couple odd things probably caused by a lack of characters- Alxasaurus sister to Erlikosaurus (one more step needed to change), Caudipteryx outside Oviraptorosauria (also one more step). Yet there are also some interesting plausible groupings such as the derived Harpymimus, alvarezsauroid Pelecanimimus, alvarezsaur-therizinosaur clade, basal Oviraptor, Zanabazar+Troodon and ornithurine Unenlagiinae. Note also that it resembles the standard topology more than TWG's original in a non-maniraptoriform Ornitholestes, paravian Troodontidae and more basal Caudipteryx.

For those interested, the following number of additional steps are needed for-

Carnosaurian tyrannosaurids as in Molnar et al. (1990)- 4.

Maniraptoran tyrannosaurids as in Sereno (1999)- 8.

Ornitholestes as an allosaurid (Paul, 1988)- 11.

Ornitholestes less derived than tyrannosaurids- 3.

Ornitholestes as a maniraptoran- 2.

Ornitholestes as a dromaeosaurid as in Makovicky (1995)- 11.

An ornithomimosaur-alvarezsaurid clade- 2.

Alvarezsaurids as basal maniraptorans outside therizinosaurs+oviraptorosaurs+paravians- 3.

Alvarezsaurids as basal paravians- 2.

Alvarezsaurids as avialans- 11.

Alvarezsaurids as ornithurines- 10 (13 with Alvarezsaurus too, which otherwise goes to Oviraptorosauria).

Alvarezsaurids and therizinosaurs joining with ornithomimosaurs as in Sereno (1999)- 5.

Enigmosauria- 2.

Oviraptorosauria being closer to birds than dromaeosaurids or troodontids- 10.

Arctometatarsalia as in Holtz (1994)- 45.

"Pneumatocrania" as in Holtz (1992/1994)- 28.

Bullatosauria- 22.

Deinonychosauria- 15(!).

Archaeopteryx being a troodontid - 4.

Dromaeosaurids being ornithurines (closer to birds than Archaeopteryx as in Paul)- 3 (troodontids also join them)

Unenlagiines being dromaeosaurids- 1.

Senter's (2007) eudromaeosaur topology- 8.

Longrich and Currie's (2009) eudromaeosaur topology- 9.Russell and Dong's (1994) crazy topology- 23.

Of course, without important taxa like basal tyrannosauroids, the mess of basal coelurosaurs, Deinocheirus, Shenzhousaurus, Haplocheirus, Falcarius, Beipiaosaurus, Protarchaeopteryx, Incisivosaurus, Pedopenna, Buitreraptor, Mahakala, Shanag, Microraptor, Austroraptor, Mei, Sinovenator, Jinfengopteryx, scansoriopterygids, Anchiornis, Shenzhouraptor, Dalianraptor, Jixiangornis and omnivoropterygids, those numbers aren't too important. But adding these taxa and the new characters of more recent TWG analyses is the next step...

The myth of coding from specimens firsthand and the untapped resource of photos

2011-05-31T18:57:00.000-07:00

You've probably heard it many times. Advice from professional paleontologists about the proper way to code specimens. For instance, here's Brochu from the DML in 2000-

"One thing I've noticed as associate editor of JVP is that reviewers are growing less patient with phylogenetic analyses that do not address the specimens themselves, and which instead code taxa from publications. This is being viewed increasingly as unacceptable, and I wholeheartedly embrace that view. It's the specimens that are our primary data."

I completely agree that the specimens are our primary data and that coding from specimens is preferrable to any other resource. When I was younger back in 2000 and such, I would picture a paleontologist poring over a specimen in his hands, turning it this way and that under the light, only to triumphantly type a 0 or 1 into Nexus Data Editor and move on to the next character. If only the world were so kind. The dirty truth is that this is generally not the way things work, and indeed can't be, given financial and business considerations.

Any decent cladistic analysis needs a large number of taxa, and for most analyses this means specimens will be spread over the world. For the original TWG analysis of Norell et al., seeing all the relevent specimens would mean going to the AMNH, BMNH, BPM, BSP, BYU, CEU, CMN, DINO, FMNH, GMV, HMN, IGM, IVPP, JM, LH, MNU, MOR, MUCP, NGMC, PIN, PVPH, ROM, RTMP, UA, UCMZ, USNM, WDC, YPM and ZPAL collections. China, Mongolia, Russia, Argentina, Poland, England, Spain, Germany, Canada and over ten states of the US. If you're lucky, you'll see the specimens on a traveling exhibit (with the caveat it usually makes them harder to examine up close) or on loan to another museum. Many museums have casts, but these are of varying quality. Realistically, very few paleontologists are going to have the resources to see all the specimens. Travel cost is simply too high.

But people do manage to travel, and many papers indicate specimens were consulted for coding. I myself visited the AMNH twice, and they happened to have many IGM specimens at the time as well. When I write my papers, I'll put down my reference for Saurornithoides as "AMNH 6516". But the truth is my codings don't come from looking at the specimen in person. I saw it, I held it, sure. But when you visit a museum collection, you get 6 hours or so per day, since they're only open for so long. And there are usually several revelent specimens in a museum, sometimes an extremely large number (AMNH, IGM, IVPP, MOR, RTMP, etc.). Moreover, there are usually rules about removing only one specimen from cabinets at a time, filling out cards to replace them in the meantime, etc.. And you want to be careful, since nobody wants to be "the one who dropped Ornitholestes' skull". If I were to try to code Ornitholestes for the TWG matrix while looking at it in the AMNH collections, it would near certainly take my entire time for that day and more. Any good matrix has at least a couple hundred characters, often several hundred. It takes time to code. And while people have the resources to visit museum collections, I highly doubt most have the resources to return every day for a week or two. And realistically, matrices aren't made by having a list of characters, and running through them for every taxon, a taxon at a time. Often comparing taxa will lead to new interpretations (as in my therizinosaur accessory trochanter example) or a taxon's morphology will lead you to redefining your states or adding a new character. Who's going to go back to New York to see if Ornitholestes has more than ten maxillary teeth after they've rewritten their character to be "11 or more teeth" instead of "9 or more"? And once you have a new/revised matrix several years down the line, and new taxa have been discovered, are you supposed to go on your whorlwind worldwide tour again? Curators can do these things for specimens in their care, as can other researchers who live by a museum or have specimens on loan to them, but nobody can do them for the majority of specimens.

So how do people "code from specimens"? They take photos. Lots of photos. And they code from those. They're often better than the literature because they're in color and from as many angles as you want, but with the internet publication quality is improving. There would be almost no reason to see Australovenator for myself, for instance, since Hocknull et al. did such a good job of photographing it. There are certainly things photographs don't show well- sutures and restoration on some specimens, depth of depressions, some texture. But these are hardly numerous enough to justify hundreds of dollars to see yourself. "The literature" has gotten a bad name, but its photos can be just as good as your own, and its descriptions are usually written by people with as much or more knowledge and experience as you. This is good news for all of us though, since it means anyone can have access to the same resources the professionals use for most specimens, without travel costs. The internet's gone a long way to providing a Shiny Digital Future for publication access, but I think we could do more.

What if there was an online database of specimen photos, in high resolution color, that anyone could access? The museums' permission would be needed of course, and undescribed specimens could be excluded if under study, but it sure beats everyone spending their resources to photograph the same things. It's also better than the current situation where people have photos of poorly described specimens, but aren't allowed to distribute them, even if they've been in the literature for over a decade and have no plans for redescription. The odd thing is, a person is generally allowed to travel to the collection and take their own photos, but not recieve or distribute those which have already been taken. I don't want people to think I'm just bitter about lacking access myself, as there are plenty of specimens I have photos of (both taken myself and kindly provided by others) and aren't allowed to distribute. So I'm on both sides. But surely such a system is broken when we're witholding information from each other that we could get for hundreds of dollars in travel fees and won't be redescribed soon anyway.

I'd be willing to throw my (distributable) photos into such a project if someone were to set it up. The primary obstacle besides getting museum permission would be the huge storage space, but it could probably even be done on Flickr or Picasa. What does everyone think?

Accessory trochanters in therizinosaurs

2011-05-27T17:59:00.000-07:00

While doing my work on the TWG matrix, I noticed something interesting. A brief intro to the structures described here is helpful. Theropods have an anterior trochanter (also called lesser trochanter) on the front of their proximal femur. In birds and various maniraptoriforms it partially or completely fuses to the greater trochanter to form a trochanteric crest. First recognized in Microvenator, a lot of taxa also have another trochanter right below the anterior trochanter, called the accessory trochanter. Supposedly, therizinosauroids have a low, separate anterior trochanter but no accessory trochanter. I think people have just been confusing their accessory trochanter for an anterior trochanter, while the real anterior trochanter is fused in a trochanteric crest. Note the figure below...

The top row is from Hutchinson's (2001) femoral paper. The anterior trochanter is 'lt' while the accessory trochanter is 'at'. I've outlined the accessory trochanter in purple in all figures. On the left bottom we have basal therizinosaur Falcarius (from Zanno, 2010a), which Zanno correctly realized has both an accessory trochanter and an anterior trochanter which is closely appressed to the greater. The outline drawing is of Alxasaurus (from Russell and Dong, 1994), which was supposed to have a low cylindrical anterior trochanter. But note that it is low in position like an accessory trochanter instead and that the greater trochanter is as wide as those taxa which incorporate the anterior trochanter into a trochanteric crest. Next on the bottom row is an anterior view of Segnosaurus (from Zanno, 2010b). Here too the anterior trochanter is supposed to be low (labeled flt), but again I think it matches an accessory trochanter more. Finally, in the lower right is Chirostenotes (from Currie and Russell, 1988) in anterior view. It was described as having a very low anterior trochanter, which would be quite unlike any avetheropod, but makes sense as an accessory trochanter. As ornithomimosaurs and basal oviraptorosaurs have the most distinct accessory trochanters, it makes sense that therizinosaurs and Chirostenotes would too.

References- Currie and Russell, 1988. Osteology and relationships of Chirostenotes pergracilis (Saurischia, Theropoda) from the Judith River (Oldman) Formation of Alberta, Canada. Canadian Journal of Earth Sciences. 25, 972-986.
Hutchinson, 2001. The evolution of femoral osteology and soft tissues on the line to extant birds (Neornithes). Zoological Journal of the Linnean Society. 131, 169-197.
Russell and Dong, 1994. The affinities of a new theropod from the Alxa Desert, Inner Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences. 30, 2107-2127.
Zanno, 2010a. Osteology of Falcarius utahensis: Characterizing the anatomy of basal therizinosaurs. Zoological Journal of the Linnaean Society. 158, 196-230.
Zanno, 2010b. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

Charig's thesis- "Mandasuchus" and "Teleocrater"

2011-05-24T02:55:00.000-07:00

Fitting with the basal archosaur theme of this month, here's something I've been meaning to post for a while. One of the rarest Mesozoic archosaur papers of all is Charig's (1957) unpublished thesis. Unlike Zhao (1985), which I could at least order, no one can get a copy of Charig's work. You're not even allowed to photocopy it without permission of the copyright holder, and Charig died in 1997. Even if you somehow managed to get permission from his children, it'd still cost $176 to photocopy (assuming rates have stayed the same over the last decade, which they certainly haven't here). George Olshevsky (DML, 2001), who's seen most every dinosaur paper in existence, believed "when he was alive he embargoed all the copies so that no one could obtain it." In October 2001 John Jackson went to the Cambridge Library and made notes ("paraphrasing here and there, from fairly arbitrarily chosen sections, with bits missed out"), which he gave permission to distribute. The previous person who accessed it did so in 1986, giving some idea of how rare it is. As Charig's nomina nuda are well known, the publication is 54 years old, and he won't be publishing on them, I think the information is fair to share. So without further ado, here's the closest any of us will probably get to reading Charig's thesis-

"Unfortunately the word “Nyasasaurus” does not appear in my notes.
 
The work is in two volumes: the illustrations: 53 plates, each with a facing
page of titles; and the volume of text of just over 500 pages.

Notes on:
Charig, A. J. 1957. New Triassic archosaurs from Tanganyika, including
Mandasuchus and Teleocrater. Dissertation Abstracts, Cambridge University.

[My comments in […] brackets.]
 
Mandasuchus longicervix, known from 3 specimens, and Teleocrater tanyura,
known from 2 specimens; in both genera, skull poor and post-cranial good.
 
General notes:
 
Both have closed acetabula.  Mandasuchus differs from Prestosuchus (from the
upper Rio do Rasto beds) in that Mandasuchus’s cervical vertebrae are
elongated (Prestosuchus’ are not, as far as is known).
 
The dermal armour differentiates the family [presumably Mandasuchus’s
family] from Stagolepidae (from the upper Tr of Laurasia).
 
There are no good grounds for considering the acetabulum of Spondylosaura[?]
to be open.  The neck of Spond. is more elongated than Mandasuchus.
 
Teleocrater has greatly elongated cervicals, unlike any other pseudosuchian
described, but closely resembling Coelophysis, yet it has a closed
acetabulum, and limbs like other pseudosuchians.
 
 
Diagnosis of Mandasuchus:
 
A pseudosuchian tending to large size.  The skull is unknown, except for
fragments of the maxilla and dentary, the former showing a large antorbital
vacuity; jaws long.  Dentition thecodont; teeth recurved, laterally somewhat
compressed, with anterior & posterior borders crenulated.
 
Vertebrae with the length of centrum never much less than the diameter and
usually greater than diameter.  Centra lightly amphicoelus; floor of neural
canal deeply concave in each centrum, except in posterior caudal region;
zygapophyses moderately oblique; tops of neural spines, especially in
anterior part of column, flattened and expanded to bear dorsal scutes.
 
Axial and caudal intercentra only.  More than 25 pre-sacral vertebrae
present.  Eight cervical vertabrae (by arbitrary definition) including
atlas; axis slightly elongated, other cervical vertebrae much elongated (up
to 50% over typical dorsals), elongation being greatest in 5th; axis and 3rd
cervical with prominent keel, faint ventromedial ridge in others; neural
spines low; axial and cervical ribs present, the later crocodiloid.
Seventeen or more dorsal vertebrae, centra mostly rounded beneath, some
slightly flattened; typical archosaurian shift in position of rib
articulation, parapophysis borne entirely on centrum in 2nd dorsal, on both
centrum and neural arch in 3rd & 4th, and on neural arch only on 5th;
diapophysis supported by oblique radiation buttress in anterior dorsals;
parapophysis and diapophysis tend to form “spectacles-shaped” rib
articulations then fuse in posterior dorsals; most if not all dorsal
vertebrae with hyposphene.  Two sacral vertebrae [in life probably].  Caudal
verts, except most anterior members, flattened ventrally and with
haemopophyses (absent in first three); distal caudals with small median
pre-neural spine between prezygapophyses, anterior to neural spine proper;
rami of proximal end of each haemopophysis joined by bridge, at least in
distal part of tail.
 
Major limb bones long and slender, with hollow shafts; propodials longer
than epipodials; bones of forelimb about two-thirds as long as hindlimb.
 
Scapula broad both dorsally and ventrally, only moderately inflected;
coracoid with small foramen; dermal elements of pectoral girdle not known.
Humerus with high deltopectoral crest, well-marked supinator process and
ectepicondylar groove, no entepicondylar foramen or groove; ulna without
olecranon; no manus.
 
Acetabulum closed.
 
Ilium with short anterior spine, long posterior spine, well-developed
supra-acetabular crest, forming most of the acetabulum; pubis long, with
small obturator foramen, twisted proximally in typical pseudosuchian manner,
distally plate-like and directed steeply downwards, thickening of lateral
corner of distal end; ischium also elongate, peduncle flattened laterally
and with sharp anteroventral edge, possibly not meeting its fellow in
mid-line but diverging from it distally, distal end slightly thickened.
 
Femur slightly sigmoidal, with prominent 4th trochanter high on shaft;
fibula with anterior muscle process; fibulare crocodyloid, pes otherwise
unknown.
 
Paramedian dorsal scutes, not corresponding in number with verts but more
numerous, keeled externally, each notched posteriorly and overlapping
anterior spine of scute behind it, without ornament.
 
 
Teleocrater:
 
First impression is a vertebral column of a saurischian type, associated
with the ilium and limb bones of a pseudosuchian.  The verts resemble a
coelurosaur very closely; long, especially anterior, cervicals, and
generally lightly constructed.  But the acetabulum certainly closed; humerus
has supinator process and ectepicondylar groove; femur has no well-defined
head set at an angle to the shaft, and is without a 4th trochanter; tibia
shorter than femur; fibula has lateral trochanter.
 
This specimen was found in a heterogeneous field-collection [but other
material easily distinguished from the Teleocrater stuff].  It seems most
unlikely that 28 verts from a saurischian, without any corresponding limb
bones, would be found together with 9 well-preserved pseudosuchian girdle
and limb bones lacking any corresponding verts, and the dimensions of the
two sets of bones being strictly comparable.
 
The genus must be referred to the pseudosuchians because of the apparently
closed acetabulum.  Neither specimen has known dermal scutes, but then the
type lacks the top of every neural spine, and the other specimen is too
incomplete.  The ilium and limb bones of Teleocrater, though typically
pseudosuchian in form, resemble no other known particularly, though not
widely different from Mandasuchus, despite great differences between the
vertebrae of the two.  On the other hand, the vertebral column *does*
resemble coelophysis.  There is a general resemblance between Teleocrater
and Coelophysis in their hollow, thin-walled bones.  Teleocrater is a little
smaller on average than Coelophysis.  In both, verts are long and slender,
especially in the neck and tail, and the centra are usually amphicoelous.
 
Von Heune’s axis [his Coelophysis one] resembles the Teleocrater vertebra in
extreme elongation and in the marked and asymmetric concavity of its ventral
profle, the apex of which lies in front of the middle of the vertebra.  It
seems that in both animals the anterior face of the centrum must have lain
more dorsally than the posterior, showing the head was held above the level
of the body.  There is further resemblance in the nature of the ventral
surface of the centrum: concave or flattened in front between a pair of
sharp edges, bearing a medial ridge in the middle part (much longer in
Coelophysis) and rounded behind.  The posterior face is roughly circular,
and fairly deeply concave in both.  The most striking similarity is between
the flange-like diapophyses and zygapophysial ridges of the two verts,
giving both a highly characteristic appearance.  The detailed arrangement of
the flanges and ridges is almost exactly the same.
..
..
..
Dorsal Vertebrae:
In both [Coelophysis and Teleocrater] still slender and rather elongate, but
a little stouter towards the sacrum.  There is also a resemblance in the
gradual change in position of [the?] parapophysi…
..
..
..
Caudal region:  There is also a general similarity here between [_T_ and
_C_].  _C_ however differs from Teleocrater in having no facets or
intervertebral spaces for haemapophyses (though Case opines chevrons would
be expected), and their ventral surfaces are rounded without traces of
longitudinal grooves or ridges.  In Teleocrater only the last 4 of the 15
caudals preserved have rounded ventral surfaces without haemapophysial
facets.  In both Teleocrater and _C_ the centra are weakly amphicoelous, the
flattened transverse processes, the bases of which are axially long in the
anterior cuadals, diminish down the series and disappear; the zygapophyses
remain, even in the smallest vert, and the anterior pair project in front of
the centrum; and the neural spines, which also diminish and disappear, have
an anterior edge rising obliquely backwards, and a posterior edge rising
almost vertically.
..
..
..
The lilum of _C_ and Teleocrater is utterly different.  In Teleocrater the
acetabulum is almost certainly closed. The anterior spine in Teleocrater is
extremely short.  The posterior spine in Teleocrater is broken off but seems
to have been long, and the beginning of a strong medial crest is preserved.
Case ’27 described an isolated ilium from Texas, similar in size to _C_
longicollis but “somewhat different in form.”  It was actually very
different, and is definitely not from _C_, but rather similar to Teleocrater
though about twice as large; any acetabular perforation must have been very
small.  Extremely long anterior spine and correspondingly long, very heavy
posterior spine, bearing a high medial crest.
 
The fumur of _C_ and Teleocrater differ mainly in the head in Teleocrater
being not at all bent towards the median side.  Teleocrater’s femur more
powerfully built but relatively even longer  (compared to _C_’s equivalent
to 5 of its dorsal verts) in Teleocrater equivalent to six or seven anterior
dorsal verts.  The shaft is sigmoidally curved and there is no ext.
trochanter.  The only similarities between femur of _C_ and Teleocrater are
the absence of a properly developed fourth trochanter, and the form of the
broadened, club-shaped distal end with its weakly developed condyles.
 
Tibia:
Not the remotest resemblance between the two animals.
 
Fibula: in _C_ “but little expanded.”  This differs from Teleocrater.
 
Summary:
_C_ and Teleocrater only similar in their vertebral columns.  This
similarity is no more than might be expected between any two coelurosaurs.
However there is a particularly close resemblance in the anterior cervicals,
with their highly elongate centra and characteristic flanges; this form is
most unusual and yet almost identical.
..
..
..
General Taxonomics:
Both Mandasuchus and Teleocrater are from the “upper bone bed” of
Tanganyika, and share a common tendency to resemble the saurischia to an
unusual extent.  This tendency, particularly in Teleocrater, is more
pronounced in the vertebral column than the girdle and limbs.  The two
genera are strikingly different: Mandasuchus (and other prestosuchids)
generally reminiscient of pachypodosaurs, Teleocrater very like
coelurosaurs.
 
[He considers the vert. column similarities between Teleocrater and
Mandasuchus enough to suggest acet. perforation occurred independently in
the two saurischian groups (and between 4-6 times overall).]
 
 
 
His thesis also deals with other archosaur bits from the Maleri beds of
India, all of which were described in Von Heune (‘40c): Palaeont. Indica
(n.s.) 32 memoir no. 1, 1-42.
 
 
From the Summary:
The only important difference between Mandasuchus and Prestosuchus is
Mandasuchus’s cervical verts are elongated while the latter’s (as far as is
known) are not.  It is proposed to erect a new family: Prestosuchidae for th
e two, the most diagnostic feature of which would be the dermal armour,
clearly distinguishing it from the Stagonolepidae."

Thanks to John for this interesting look at an obscure document.

Is Saltopus a silesaurid?

2011-05-20T16:35:00.000-07:00

Saltopus was recently redescribed by Benton and Walker (2011), who included it in Brusatte et al.'s (2010) archosaurian matrix. The result is that Saltopus is a dinosauriform more derived than Pseudolagosuchus but outside Silesauridae(including Lewisuchus)+Dinosauria. Since many recent analyses have synonymized Pseudolagosuchus and Lewisuchus, Tim Williams asked on the DML whether Saltopus would also be a silesaurid if Pseudolagosuchus and Lewisuchus were combined in Brusatte et al.'s matrix. Thanks to Tim, I have the Saltopus paper, so now the question can be answered.

First, I made a NEXUS file from Brusatte et al.'s matrix. Characters 52, 156, 159 and 170 had to have their states switched so that they could be properly ordered. More characters were ordered than Brusatte et al. had, with only 14, 51 and 96 left unordered. I then made a new OTU combining Lewisuchus' and Pseudolagosuchus' codings. Only two codings differed. Character 134 is the ventral emargination of the femoral head in anterolateral view seen in lagerpetonids. This was scored as present in Lewisuchus as well, and while Romer's (1972) figure does seem to show it, Arcucci (1998) determined this is actually a tibia. The other differing character is 148, the tibiofemoral ratio, which again is caused by the misidentified tibia. Thus the femoral codings of Lewisuchus were not taken into account for the combined OTU. The resulting tree is below-

|--Erythrosuchus
`--+--Euparkeria
   `--+--Proterochampsidae
      |--+--+--Paleorhinus
      | | `--+--Mystriosuchus
      | |     `--Rutiodon
      | `--+*-Stagonosuchus
      |     |*-Tikisuchus
      |     |--+--Qianosuchus
      |     | `--+--+--Aetosaurus
      |     |     | `--+--Desmatosuchus
      |     |     |     `--Stagonolepis
      |     |     `--+--Gracilisuchus
      |     |        `--+--Erpetosuchus
      |     |           `--+--Protosuchus
      |     |              `--+--Sphenosuchus
      |     |                 `--Terrestrisuchus
      |     `--+--+--Revueltosaurus
      |        | `--+--Ornithosuchus
      |        |     `--Riojasuchus
      |        `--+--+--Rauisuchus
      |           | |--Saurosuchus
      |           | |--+--Batrachotomus
      |           | | `--Prestosuchus
      |           | `--+--Postosuchus
      |           |     `--Teratosaurus
      |           `--+--+--Arganasuchus
      |              | `--+--Fasolasuchus
      |              |     `--Ticinosuchus
      |              `--+--Yarasuchus
      |                 `--+--+--Lotosaurus
      |                    | `--+--Effigia
      |                    |     `--Shuvosaurus
      |                    `--+--+--Arizinasaurus
      |                       | `--Bromsgroveia
      |                       `--+--Poposaurus
      |                          `--Sillosuchus
      `--+--+--Scleromochlus
         | `--+--Dimorphodon
         |     `--+--Eudimorphodon
         |        `--Pteranodon
         `--+--+--Dromomeron
            | `--Lagerpeton
            `--+--Marasuchus
               `--+--Lewisuchus (inc. Pseudolagosuchus)
                  `--+--Saltopus
                     `--+--+--Silesaurus
                        | `--+--Eucoelophysis
                        |     `--Sacisaurus
                        `--+--+--Psittacosaurus
                           | `--+--Heterodontosaurus
                           |     `--Lesothosaurus
                           `--+--Herrerasaurus
                              `--+--Plateosaurus
                                 `--Coelophysis

Note that basically, the combined Lewisuchus+Pseudolagosuchus goes where Pseudolagosuchus used to. So it really doesn't answer our question. Also note that proper ordering changed a lot of relationships within Suchia from Brusatte et al.'s tree.

To resolve whether Saltopus would be a silesaurid in a topology where Lewisuchus is a member of the family, I constrained the results to agree with Nesbitt's tree for all taxa used in both analyses. The result is 47 steps longer and is interesting in-

- finding Gracilisuchus sister to Revueltosaurus+Aetosauria (as in some trees of Nesbitt's).

- finding Erpetosuchus sister to Crocodylomorpha (as in Brusatte et al.).

- finding Arganasuchus to be a pseudosuchian outside Ornithosuchidae, Gracilisuchus+Aetosauria, Poposauroidea and Teratosauridae+Crocodylomorpha.

- finding Stagonosuchus to be the most basal loricatan.

- finding Tikisuchus to be a teratosaurid (rauisuchid of Nesbitt) (as in Brusatte et al.).

- finding Yarasuchus the most basal poposauroid (as in Brusatte et al.).

- finding Bromsgroveia to be at least as derived as Arizonasaurus but outside Lotosaurus+Shuvosauridae (as in Brusatte et al.).

- finding Scleromochlus to be a pterosauromorph (as in Brusatte et al.).

Saltopus forms a polytomy with Dinosauria and all four silesaurids, so may be a silesaurid or may not. And we're no closer to answering the question that when we began. It might be more useful to code it for Nesbitt's matrix.

Where are the pterosaurs recoded for Nesbitt's matrix, you may ask. I'm afraid once again work on a paper to be published has superceded this more recreational study. Luckily, it's work that coincides with my TWG analysis and should result in coauthorship of a new taxon. I will say that Nesbitt didn't code several pectoral and forelimb characters for pterosaurs, which when coded make them less likely to be archosaurs. However, the braincase of Pteranodon makes them more likely to be archosaurs. So after adding Preondactylus and Pteranodon, and recoding Eudimorphodon and Dimorphodon (but with no hindlimb characters looked at yet), they're still avemetatarsalians and take 17 steps to move them outside Archosauria by Peters' 'key taxa'.

Sharovipteryx in Nesbitt's matrix

2011-05-08T23:35:00.000-07:00

The last of Peters' (2000) "key taxa" to placing pterosaurs outside Archosauriformes is Sharovipteryx. Another taxon which was originally poorly illustrated and described, Gans et al. (1987) did a mediocre job redescribing it, and good photos are available of some areas. Unwin et al. (2000) provide some new information. Like Longisquama, Peters' imagination is at play in the 2000 paper. The forelimbs were not exposed at the time and the skull is in dorsal view, not ventral.

After coding, Sharovipteryx joins the other discussed taxa somewhere basal to Erythrosuchus. The topology is- (Sharov(Cose,Lango)(Longi(Valle,Megalanc))). As before, 13 more steps are needed to take pterosaurs out of Archosauriformes. They're still closest to simiosaurs, then Longisquama, with Sharovipteryx the next outgroup.

Next up, the pterosaurs themselves.

Simiosaurs in Nesbitt's matrix

2011-05-08T18:25:00.000-07:00

Simiosaurs such as Megalancosaurus are one of the most controversial groups of diapsids. While generally placed among basal archosauromorphs, they've also been considered non-saurians (Senter, 2004), euryapsids (Muller, 2004), lepidosauromorphs (Peters, 2007) and theropods (Olshevsky, 1991). They've also been attached to both pterosaur (Peters, 2000; Renesto and Binelli, 2006) and bird (Feduccia and Wild, 1993) ancestry.

Enforcing Cosesaurus and Longisquama to be pterosauromorphs is five steps longer, and they along with simiosaurs and Langobardisaurus end up as basal avemetatarsalians. Enforcing Cosesaurus and Longisquama to be pterosauromorphs and placing the clade outside Archosauriformes is thirteen steps longer. In this topology, they are prolacertiforms, simiosaurs and closest to pterosaurs, with Longisquama one node out. This is ten steps longer than Renesto and Binelli's (2006) topology where simiosaurs+pterosaurs are sister to archosauriforms and prolacertiforms with Langobardisaurus and more basal. Enforcing Megalancosaurus to be a theropod is 34 steps longer (Longisquama and Vallesaurus follow it). I neglected to mention last time that Olshevsky also placed Cosesaurus in Theropoda, which takes 41 more steps, with simiosaurs, Longisquama and Langobardisaurus following. So Olshevsky was near certainly wrong about either Megalancosaurus or Cosesaurus being theropods, though Longisquama is more equivocal.

Notice the trend for how much less parsimonious it is to contrain pterosaurs as non-archosauriforms.
- Longisquama added. 23 more steps.
- Longisquama and Cosesaurus added. 22 more steps.
- Longisquama, Cosesaurus and Langobardisaurus added. 15 more steps.
- Longisquama, Cosesaurus, Langobardisaurus and simiosaurs added. 13 more steps.

Next up before I add Preondactylus and Pteranodon (and check the other pterosaurs' coding) is Peters' (2000) last "key taxon" Sharovipteryx. Will it make non-archosauriform pterosaurs even more parsimonious?

Langobardisaurus in Nesbitt's matrix

2011-05-07T17:33:00.000-07:00

Continuing the series, I added the tanystropheid Langobardisaurus to Nesbitt's new archosauriform analysis. Langobardisaurus is another taxon which Peters (2000) considered key to connecting prolacertiforms with pterosaurs. It's very odd in its own right, especially its somewhat artiodactyl-like skull. Luckily, several specimens have been well described and it's better preserved than Longisquama or Cosesaurus. Once coded, it groups with Longisquama and Cosesaurus, but this clade can vary in position. It can be anywhere outside Pseudosuchia or Ornithodira. Constraining prolacertiform pterosaurs is now only 15 steps longer, compared to 22 steps before Langobardisaurus was added. What will happen when Vallesaurus and Megalancosaurus are added?

Cosesaurus in Nesbitt's matrix

2011-05-07T13:36:00.000-07:00

I haven't written the Cosesaurus entry for my site yet, but to me it always seemed the BANDits best bet, though instead they went with the weird Megalancosaurus and parafeathered Longisquama. Cosesaurus looks outwardly like a little theropod, though of course it differs in the details. Like Longisquama, its anatomy has not been redescribed since the 70s and the existing reconstructions involve lots of imagination. The thing's preserved as a sandstone impression, and Ellenberger (1977) saw lots of feathers and drew numerous lines in and around the skull that have no guarantee of reflecting morphology. Peters (2000) handled it better, but like in Longisquama identified antorbital fenestrae and suture details that Ellenberger didn't see, which makes me suspicious. So again I coded it conservatively, using only the sutures agreed upon by both authors and Peters' interpretation of the pelvis. I'm curious about including Cosesaurus not only because it's one of Peters' proposed non-archosaurian pterosaur relatives but also to address the argument that pterosaurs only clade with avemetatarsalians because there's nothing better in the matrix. Would Cosesaurus also clade with avemetatarsalians despite its primitive anatomy? Would it draw pterosaurs out of Archosauria?

The answer is that Cosesaurus emerges basal to Erythrosuchus, in a polytomy with Mesosuchus, Prolacerta, proterosuchids and higher archosauriforms. If Longisquama is included as well, both clade with Prolacerta. So it seems Nesbitt's matrix handles basal taxa just fine. Only four steps move it sister to pterosaurs in Avemetatarsalia though, which is somewhat worrying. It takes 22 more steps to move pterosaurs out with them in Prolacertiformes.

We'll see how this develops with the addition of unambiguous tanystropheid Langobardisaurus, a couple simiosaurs, Preondactylus and Pteranodon. I'll also be checking the general pterosaur codings when coding them, to make sure Nesbitt didn't assume homology a priori by e.g. coding manual digit IV as unknown in amount of reduction.

Longisquama in Nesbitt's matrix

2011-05-07T03:09:00.000-07:00

Here's an interesting one. Longisquama has an extremely controversial phylogenetic position. It's been placed outside Sauria, as a lepidosauromorph, a tanystropheid, a non-dinosaurian archosauromorph and even a theropod. See my discussion here for details. Nesbitt's matrix cannot test most of these, since it only covers archosauriforms. But I was curious what would happen if it was added to the matrix, since it's been allied with pterosaurs by some, and the BAND crowd insists it's an archosauriform. Not that the latter would believe a cladistic analysis, but meh...

Unfortunately, Longisquama's morphology is also controversial, and has yet to be studied in depth. Such basic features as the antorbital fenestra and tooth implantation are not agreed on by all authors. So I coded Longisquama twice. One uses Peters' (2000) interpretation of skull elements and the sternum-interclavicle structure. The other uses the minimum codable without dividing the skull into discreet elements and treating the aforementioned pectoral structure as "bony wisps that defy interpretation" as interpreted by Senter (2003).

Perhaps unsurprisingly, its position depends on how it's coded. Coding it conservatively results in Longisquama being outside Archosauriformes alongside Mesosuchus and Prolacerta. Constraining it and pterosaurs to be sister taxa is only two steps longer, and puts both in Avemetatarsalia. Constraining it as a theropod is seven steps longer, and it emerges as the basalmost one. Coding Longisquama as Peters illustrates it (this was before he thought he saw the hindlimbs and such) results in it being a pterosauromorph, with pterosaurs in their usual position. Constraining it to be outside Archosauriformes is only three steps longer.

In conclusion, Longisquama desperately needs redescribed. Ignore the parafeathers, we need its basic anatomy established. While moderately rejected as a theropod, I'd say it could equally well be a non-archosauriform or a pterosauromorph regardless whose reconstruction is used.

Lukousaurus in Nesbitt's matrix

2011-05-07T02:09:00.000-07:00

Back in ye olde days when I was new to the DML, I wrote a post on Lukousaurus to determine its phylogenetic affinities- http://dml.cmnh.org/2000Sep/msg00086.html . I didn't have anywhere near the amount of knowledge and resources I do now, and I considered it an abelisaurid or sphenosuchian. Times have changed and now we have Nesbitt's huge new analysis which is perfect for coding Lukousaurus in. It doesn't have abelisaurids, but does have Dilophosaurus and Allosaurus along with several sphenosuchians. Note the caveat that Lukousaurus is coded from Young's 1948 figures and description. So after entering Lukousaurus, there are 4683 MPTs with Lukousaurus as an archosaur in all of them. It is not a member of Ornithosuchidae, Revueltosaurus+Aetosauria, Poposauroidea, Loricata or Dinosauromorpha. So it's probably some sort of basal pseudosuchian...

By the way, I noticed when coding that as in Smith et al.'s matrix, Marasuchus is not coded for its maxilla, even though Nesbitt lists the specimen as one of those he used for scoring, and lists the maxilla's presence in the material. Also Coelophysis is oddly coded for osteoderm character 408, despite lacking osteoderms.

More added taxa to follow...

Nesbitt's excellent new analysis

2011-05-04T16:39:00.000-07:00

I just wanted to state my praise for Sterling Nesbitt and his amazing new archosaurian phylogeny paper. The taxon sampling is extensive, with discussions of which material is used for each taxon. The characters are described in great detail and illustrated wonderfully, with the specimens they're found in often listed. Alternative phylogenies are examined and character support is discussed. The matrix seems completely coded. I chuckled at the dismissals of Lucas' "superficial" taxonomic discussions. :) This is surely one of the best archosaurian analyses published, and that includes ALL archosaurian analyses, on theropods, birds, crocs, you name it. But it just wouldn't be like me to not include some criticisms, so I offer the following...

On page 236, Nesbitt discusses the position of pterosaurs, which is as basal avemetatarsalians. Note this doesn't mean much in regard to the controversy of their wider relationships among reptiles, since simiosaurs, Longisquama and tanystropheids were not included. Nesbitt tries to counter Bennett's (1996) statement that pterosaurs don't have many synapomorphies of archosauriform clades more inclusive than Ornithodira with a list of the synapomorphies of Crurotarsi sensu lato, Archosauria, Archosauriformes, etc., detailing which are found in pterosaurs. This is all fine except that 13 of the characters are simply stated to be "not known in basal pterosaurs". I can't help but wondering if these (generally difficult to observe features in the braincase, tarsals and such) are known to be absent in derived pterosaurs. If so, they should still count against pterosaurs being in the listed clades. In fact, I wonder why no derived pterosaur like Pteranodon was included, when derived members of other clades (e.g. Alligator, Allosaurus, Velociraptor) were used to increase the informativeness of characters.

Note Nesbitt's Rauisuchidae should be called Teratosauridae, assuming Teratosaurus is in its standard position by Polonosuchus and Postosuchus.

I would have liked to see Doswellia, Trialestes, "Zanclodon" arenaceus, Erpetosuchus (oddly included in the character descriptions, but not the matrix), Hallopus and/or Macelognathus, Scleromochlus and Preondactylus included.

On page 187, Nesbitt is right to note that many analyses have "Characters just listed with no, little, or
vague explanations". How reduced is "reduced"? How tapered is "tapered"? Unfortunately, Nesbitt's characters sometimes have the same problem. For instance, character 282 is "Pubis, length: (0) shorter or subequal to the ischium; (1) longer than ischium." The word "subequal" should be expunged from character descriptions, since it's not quantified. If I have a taxon with a puboischial ratio of 101%, that's presumably subequal. But what if it's 103%? 106%? Everyone's conception will be different, and this will lead to miscodings. Or character 259- "Metacarpal IV: (0) present; (1) reduced to a nubbin or absent." When is a metacarpal a "nubbin"? Or character 266- "Ilium, crest dorsal to the supraacetabular crest/rim: (0) vertical; (1) anterodorsally inclined." Vertical compared to what basis of horizontal (sacrum axis, axis between anterior and posterior tips, axis formed by ventral extent of peduncles, etc.), and would 92 degrees count as vertical or inclined? These kinds of issues are found in almost every analysis, so this isn't a critique of Nesbitt as much as it's an urging to all of us to explicitly define our character states.

But these issues aside, the paper is extremely well done. Besides the above taxa, someone should use this matrix to place Arganasuchus, "Cryptoraptor", Lagosuchus, Lukousaurus, Razanandrongobe, Saltopus, Spondylosoma, Stagonosuchus, Yarasuchus and Zanclodon.

Nesbitt, 2011. The early evolution of archosaurs: Relationships and the origin of major clades. Bulletin of the American Museum of Natural History. 352, 292 pp.

Pneumatocrania and Holtz's thesis

2011-05-01T20:03:00.000-07:00

Everyone knows Holtz's famous 1994 paper revolutionizing theropod phylogeny. What fewer people have seen is the 1992 thesis that preceded it, which included its own phylogenetic analysis. The analysis had largely similar characters (128 vs. 126) and included Procompsognathus, Piatnitzkysaurus, Eustreptospondylus and Chilantaisaurus in addition to the taxa from 1994. It also split Ornithomimosauria into Harpymimus, Garudimimus and Ornithomimidae, and did not include Abelisauridae.

The results are similar to the 1994 paper, with the following differences.
- Procompsognathus is outside Eutheropoda.
- Elaphrosaurus is a non-avetheropod tetanurine more derived than Torvosaurus, though on page 264 he notes the characteristics of abelisaurids indicates they and Elaphrosaurus are neoceratosaurs.
- Megalosaurus is a basal carnosaur (along with Piatnitzkysaurus).
- Chilantaisaurus is carnosaur in a trichotomy with Allosaurus and Acrocanthosaurus, and Eustreptospondylus is sister to this group.

Some new names are proposed.
- Eutheropoda is the group containing Ceratosauria sensu lato and Tetanurae, but not Procompsognathus. It's been used informally this way online since the 90s, including on Holtz's site, but I think Novas et al. (2003) have been the only authors to publish it. They used it in the same way (excluding Herrerasaurus and Eoraptor this time), but it's just an abstract.
- Eumaniraptora is first used here, though in a different sense than what was later adopted once it was published in 1997. In Holtz's thesis, Eumaniraptora is what we would now call Maniraptoriformes- the group containing paravians, oviraptorids and arctometatarsalian taxa.
- Holtz used Dinoaves for the Paraves group of dromaeosaurids and Archaeopteryx, though this originally referred to something like Tetanurae when Bakker coined it.
- Arctometatarsalia is proposed here, with the same content as the 1994 paper.
- Pneumatocrania is a name that hasn't made it to the internet before now. It was Holtz's name for his clade of oviraptorids and 'arctometatarsalians', since they were diagnosed in part by pneumatic skulls. Of course, we now know dromaeosaurines reduced their pneumaticity and most of the characters used are problematic (see characters 17, 64, 68, 69, 103, 115, 116 and 121 in my link above), so the topology hasn't been found since.

My favorite part of the thesis is the detailed discussion of twenty-nine poorly known theropod taxa. This includes prescient aspects such as a maniraptoriform Microvenator and a suggestion of elaphrosaur affinity for Chuandongocoelurus almost a decade before I thought the same thing on the DML. It also features some common but incorrect ideas of the early 90's though, such as neoceratosaurian spinosaurids and Carcharodontosaurus.

Thanks to Tom Holtz for permission to write about this interesting piece of theropod history.

References- Holtz, 1992. An unusual structure of the metatarsus of Theropoda (Archosauria: Dinosauria: Saurischia) of the Cretaceous. Unpublished PhD thesis. Yale University. 347 pp.

Holtz, 1994. The phylogenetic position of the Tyrannosauridae: Implications for theropod systematics. Journal of Paleontology. 68(5), 1100-1117.

Novas, Haro and Canale, 2003. Un nuevo terópodo basal de la Formación Ischigualasto (Carniano) de la provincia de San Juan, Argentina. Ameghiniana. 40(4), 63R.

Maxillary fenestra - a preview

2011-04-28T01:29:00.000-07:00

Last time I described my in progress paper. While one of the downsides to preparing something for publication is that I have to keep the results to myself until it's out, here's a preview of what the paper will be like, using the classic "maxillary fenestra" character. So far I've only dealt with the characters and taxa of the first TWG matrix- Norell et al., 2001, NEA01 below). I list the improved version of the character, the old version, include comments on its original use and other issues, then list the distribution with explicit references (to two specimens if possible). Note while many of the codings can be backed up by personal observation, the literature references allow other workers to check even without access to the specimens. Entries with asterisks are those differing from Norell et al.'s codings, which are elaborated upon and figured when a coding is changed to another (unless the original coding was "?"). This makes coding differences explicit and transparent, and will facilitate resolution.

4. Maxilla - lateral surface of antorbital fossa anterior to antorbital fenestra - solid (0); with maxillary fenestra entering maxillary antrum (1).

=4 in NEA01. Pronounced, round accessory antorbital fenestra absent (0) or present (1).

Comments- An extremely commonly used character in theropod analyses, Gauthier first (1984) used it to distinguish tetanurines then included it in a matrix for that purpose in 1986 (character 37). Note the medial wall of the maxillary antrum may not be fenestrated, leading to the appearance of a maxillary fossa instead of a fenestra as in Byronosaurus (IGM 100/983; Makovicky et al., 2003- fig. 7). The condition in oviraptorids is interpreted here differently than in most sources. The basal oviraptorosaur Incisivosaurus shows a large fenestra at the anterior rim of the antorbital fossa and a smaller fenestra posterodorsal to it. As these match the position of the promaxillary and maxillary fenestrae (respectively) in dromaeosaurids, they are homologized here. Oviraptorids have the same arrangement of fenestrae, but their promaxillary fenestra is enlarged and maxillary fenestra highly reduced, as exemplified by Citipati.

Something I threw together to approximate a figure I want in the final paper. Saurornitholestes maxilla RTMP 94.12.844 (left), Incisivosaurus skull IVPP V13326 (center) and Citipati skull IGM 100/978 (right) showing proposed homology of promaxillary (red) and maxillary (blue) fenestrae. Incisivosaurus from Balanoff et al. (2009), Citipati from Norell et al. (2002).

0- *Pelecanimimus LH 7777 (Perez-Moreno et al., 1994- fig. 2). Only one accessory fenestra is reported, which has usually been identified as a maxillary fenestra. However, its low position at the ventral border of the antorbital fossa matches ornithomimosaur promaxillary fenestrae and it is here identified as such.

Erlikosaurus IGM 100/111 (Clark et al., 1994- figs. 1 and 2). Note that the antorbital fossa wall is incomplete, but any fenestra would have to be positioned more ventrally than in other taxa if it was in the now broken area.

Chirostenotes ROM 43250 (Sues, 1997- fig. 1). While there are two fossae in the antorbital fossa, both are anterior to the maxillary antrum, which has a solid lateral wall.

*Conchoraptor ZPAL MgD-I/95 (Elzanowski, 1999- fig. 2). Labeled maxillary foramen is probably the promaxillary as noted above.

0+1- *IGM 100/42. Present on the left side, but not the right based on photos. Note Barsbold et al. (1990- fig. 10.1) incorrectly illustrate the area.

1- Sinraptor IVPP V10600 (Currie and Zhao, 1994- fig. 4 as pneumatic opening 8, following Witmer, 1997- 42).

Allosaurus AMNH 600 (Osborn, 1903- fig. 1), USNM 4734 (Gilmore, 1920- fig. 12).

Gorgosaurus CMN 2120 (Lambe, 1917- fig. 8), RTMP 83.35.100 (Witmer, 1997- fig. 30).

Tyrannosaurus AMNH 973 (Osborn, 1912- fig. 22), FMNH PR2081 (Brochu, 2003- fig. 8).

Ornitholestes AMNH 619 (Osborn, 1916- fig. 1).

*Harpymimus IGM 100/29 (Kobayashi and Barsbold, 2005a- 100).

Garudimimus IGM 100/13 (Kobayashi and Barsbold, 2005b- fig. 2). The authors' identifications are switched, as ornithomimosaurs' ventral fenestra enters the promaxillary recess (Tahara and Larsson, 2011- 130).

*Gallimimus ZPAL MgD-I/1 (Osmolska et al., 1972- pl. 30). While Norell et al. (2001) coded this differently, the plate seems to show promaxillary and maxillary fenestrae separated by a horizontal bar as in other ornithomimosaurs. Kobayashi (2004) codes this as polymorphic in his version of the TWG matrix, perhaps indicating some specimens differ from ZPAL MgD-I/1.

Struthiomimus RTMP 90.26.1 (Sereno, 2001- fig. 13).

Caudipteryx BPM 001 (Zhou et al., 2000- pl. 3), NGMC 97-9-A (Ji et al., 1998- fig. 6).

*Rinchenia IGM 100/32A.

Sinornithoides IVPP V9612 (Currie and Dong, 2001- 1754).

Saurornithoides AMNH 6516 (Norell et al., 2009- fig. 3).

Zanabazar IGM 100/1 (Norell et al., 2009- fig. 22).

Byronosaurus IGM 100/974 (Bever and Norell, 2009- fig. 7), IGM 100/983 (Makovicky et al., 2003- fig. 3).

Troodon CMN 12392 (Currie, 1985- fig. 2), MOR 246-11 (Varricchio et al., 2002- 566).

Sinornithosaurus IVPP V12811 (Xu and Wu, 2001- fig. 2).

*Saurornitholestes RTMP 94.12.844 (Currie and Varricchio, 2004- fig. 4.2).

Tsaagan IGM 100/1015 (Norell et al., 2006- fig. 3).

Velociraptor AMNH 6515 (Sues, 1977- fig. 1), IGM 100/25 (Barsbold and Osmolska, 1999- fig. 1).

Deinonychus YPM 5232 (Ostrom, 1969- fig. 6).

Achillobator FR.MNUFR-15 (Perle et al., 1999- fig. 2).

Archaeopteryx JM SoS 2257 (Paul, 2002- pl. 7), WDC-CSG-100 (Mayr et al., 2007- fig. 5).

*Confuciusornis GMV-2130 (Chiappe et al., 1999- fig. 15), GMV-2131 (Chiappe et al., 1999- fig. 16). While Norell et al. (2001) scored this feature as absent, the single accessory fenestra is here identified as a maxillary fenestra due to its posterior placement and the lack of a dorsal maxillary process which could contain a promaxillary recess.

?- Shuvuuia. Both Chiappe et al. (2002- 92, fig. 4.3) and Sereno (2001- fig. 12) identified maxillary fenestrae in IGM 100/977. However, the right maxillary fenestra in Chiappe et al.'s figure 4.3 is located far anterior to the left, and Sereno's figure 10 shows it is a break in the maxilla anterior to the antorbital fenestra. Sereno also places the maxillary fenestra anteriorly, and his reconstruction differs from the material in having a defined dorsal edge to an antorbital fossa anterior to the antorbital fenestra. While there at first glance does appear to be a well defined ventral edge, this is more probably caused by dorsoventral crushing which ventromedially displaced the portion of the maxilla anterior to the fenestra. This is confirmed by IGM 100/1001 (Chiappe et al., 2002- fig. 4.5), which shows no fossa anterior to the antorbital fenestra. The supposed left maxillary fenestra of Chiappe et al. is defined posteriorly by an anteriorly curved structure with a flared base, which does not contact the maxilla dorsally. This is congruent with a palatine, but not part of the maxilla. As Chiappe et al. (2002- 92) note, no specimen preserves a medial antorbital fossa wall, so the presence of a maxillary fenestra is unknown.

*Oviraptor (coded 1 by Norell et al., 2001). Norell et al. coded this based on what is here identified as the promaxillary fenestra. While there is a hole in the proper position for a maxillary fenestra in the left maxilla (AMNH 6517, Clark et al., 2002- fig. 11), numerous other holes are also present which are caused by damage.

"Ingenia" (coded 0 by Lu, 2004). As Lu identifies the promaxillary fenestra of oviraptorids as a maxillary fenestra, his statement "Ingenia" lacks the opening is here applied to the promaxillary fenestra.

First publication submitted, second in progress

2011-04-26T19:32:00.000-07:00

And it's been a while again. Why, you ask? One reason is two weeks ago, I finally got my first paper submitted with David Marjanovic as coauthor. Unlike blog posts, manuscripts require a ton of double-checking and tweaking, so that took quite a while. Now for the peer review process...

And now that my first paper is in the system, I've been working on my second. This one is a detailed reanalysis of the Theropod Working Group matrix. Back on the DML I once praised invertebrate zoologist Ronald Jenner for his paper on how flawed current cladistic practices are. Unfortunately, as you would have gathered from my posts, things have only gotten worse since then. Jenner notes "Rather than representing occasional lapses of judgement, most of the identified errors are symptomatic of a generally cavalier attitude towards character study. A major aim of future cladistic analyses of the Metazoa must therefore be the correction of the many errors through a more detailed and explicit approach to character study." And "It is a striking observation that none of the recent cladistic studies of the Metazoa comprehensively support all data matrix entries with source citations." These are both just as true for theropod analyses.

I figure what better place to start than the TWG matrix? It's accurate in general, uses species-level OTUs, covers a wide and controversial swath of taxa, and most importantly is used by the majority of coelurosaur workers when they describe a new taxon. Over thirty papers have used variants, including over 120 taxa. The goal is not to make a new analysis, since that's a huge long-term project. Instead, the TWG characters (including those from all derivative analyses) will be discussed and refined, but kept as close to their original intent as possible. States will be explicitly and quantitatively defined, and codings will be defended with references to exact specimens or literature. The resulting trees will then be discussed with an emphasis on how parsimonious various alternative topologies are, and how much of the proposed evidence has been incorporated into the dataset.

This way future workers will have a better dataset to plug their taxa into, and any coding disagreements can be more easily resolved. It will also give us a better idea of the current state of coelurosaur phylogenetics and provide suggestions for which characters should be added in future modifications to further our understanding.

Eodromaeus thoughts

2011-03-29T17:50:00.000-07:00

I just added Eodromaeus to the Database and noted a few things.

- PVSJ 563 was listed as a paratype, but this is a typo (Sereno, pers. comm.).

- Eodromaeus specimens were thought to be Eoraptor until 2000, but Sereno (pers. comm.) confirms there are indeed several specimens besides the holotype correctly referred to Eoraptor that await description.

- Several of Eodromaeus' listed autapomorphies are shared with Herrerasaurus, such as the ventrally convex maxillary alveolar margin (more poorly developed in Sanjuansaurus), large distal carpal 5 overlapping distal carpal 4 with a posteroventral heel (note Sereno misidentified carpal 5 as 4 in 1993- Ezcurra, 2010), and pubic apron with sinuous lateral margin (in Sanjuansaurus too, but not developed much in Staurikosaurus). Of course Eodromaeus specimens are adult so it's not a synonym, but these might be saurischian/theropod plesiomorphies.

- The supposed small herrerasaurid forelimb MACN-PV 18.649a mentioned by Ezcurra and Novas (2007, 2008) may be referrable to Eodromaeus. It was referred to Herrerasauridae due to- enlarged distal carpal V; manual phalanx I-1 longer than metacarpal I; strongly curved manual unguals; metacarpals IV-V ventral to the others. All of these are present in Eodromaeus as well. Ezcurra (2010) states that it differs from Herrerasaurus in having manual phalanx II-1 with a conspicuous longitudinal ridge on its proximolateral border. Eodromaeus does have a marked proximolateral projection on II-1, but whether this is a ridge or not is not described. Ezcurra's (2010) matrix could be checked for further information on the forelimb's morphology, which could then be compared to Eodromaeus.

- In Martinez et al.'s (2011) cladogram, Tawa is the basalmost coelophysoid. In this case, Avepoda contains Tawa and other coelophysoids under ACCTRAN character optimization, but excludes Coelophysoidea under DELTRAN optimization. Gotta love apomorphy-based definitions...

References- Ezcurra and Novas, 2007. New dinosaur remains (Saurischia: Herrerasauridae) from the Ischigualasto Formation (Carnian) of NW Argentina. Ameghiniana. 44, 17R.

Ezcurra and Novas, 2008. A review of the dinosaur diversity of the Ischigualasto Formation (Carnian, NW Argentina): Insights on early dinosaur evolution. in Langer, Bittencourt and Castro (eds.). Boletim de Resumos, VI Simposio Brasileiro de Paleontologia de Vertebrados, Paleontologia, Edicao especial. Universidad de Sao Pablo: Ribeirao Preto. 88-89.

Ezcurra, 2010. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: A reassessment of dinosaur origin and phylogeny. Journal of Systematic Palaeontology. 8(3), 371-425.

Martinez, Sereno, Alcober, Columbi, Renne, Montanez and Currie, 2011. A basal dinosaur from the dawn of the dinosaur era in Southwestern Pangaea. Science. 331, 206-210.

Halfway back to theropods with sauropodomorph Eoraptor

2011-03-28T04:58:00.000-07:00

When Eodromaeus was described, much was said about the analysis placing Eoraptor in Sauropodomorpha. What nobody did was elaborate on why Martinez et al. (2011) placed it there and how strong the evidence is. So I made a NEXUS file from Martinez et al.'s matrix to extract the character evidence.

The first thing to note is that the characters listed as multistate don't correspond to those with more than two states in the matrix, which also means the characters said to be ordered aren't those that should be. So I ordered 51, 69, 70, 76 (though nothing is coded with state 2, making ordering useless), 102 and 117. In addition, the definitions of some multistate characters have problems. "Premaxillary tooth number: 4 (0); 3 (1); 5 or 6 (2)" should ideally be ordered, but states 0 and 1 need to be switched so that the intermediate state is in the middle. "Maxillary/dentary crowns, shape: recurved (0); subtriangular (1); lanceolate (2)" artificially separates the morphology of sauropodomorph and ornithischian teeth, which are after all both triangular and lanceolate in both clades. The current coding doesn't let the reduced curvature group them together. "Ilium, preacetabular process, shape: tab-shaped (0); strap-shaped (1); subtriangular (2); semicircular (3)" is problematic since the next character deals with preacetabular length, and the only difference between "strap-shaped" and the other choices is length. "Ilium, bevis[sic] fossa, shape and orientation: broad laterally-open depression (0); shallow groove or absent (1); arched ventrally-opening ovate or parallel-sided depression (2); arched ventrally-opening posteriorly-expanding to a width approximately 50% of its length (3)" combines a lot of independant variables. There's depth (already partly covered by another character), orientation, proportional width and posterior expansion. Oddly, lagerpetonids and Marasuchus are coded inapplicable, despite their correct state of "absent" being covered by state 1. So given those issues, I ran the matrix and found similar results to Martinez et al.- 3 MPTs of 247 steps each, CI of .615 compared to his 3 MPTs 246 steps each with a CI of .618. The topology is identical. If you don't constrain the outgroups to be in the order (hypothetical(Lagerpetonidae(Marasuchus(Silesauridae,ingroup)))), then you get a lot more trees, sometimes with non-dinosauriform sauropodomorphs, and/or ornithischian silesaurids and/or Marasuchus, presumably because characters supporting more basal nodes weren't included.

So that's the matrix, but what about Eoraptor's sauropodomorph position? It's supported by the following characters-

2. external naris size large, expanded narial margin.
The plesiomorphic state specifies a tapered snout, but some taxa coded 0 like Herrerasaurus, Eodromaeus and Ceratosaurus certainly don't have tapered snouts. If you measure Eoraptor's naris compared to its skull length, then yes it looks large. But that's because it has a short snout. If you measure naris length compared to some more neutral value such as skull height at the orbit, its naris is actually smaller than any other taxon in the matrix. Also, Panphagia does not preserve a premaxilla, so cannot be coded, contra the matrix.

19. nasal posterolateral process present.
This is actually unknown in silesaurids and Tawa (Nesbitt et al., 2009), though Panphagia has it (Martinez and Alcober, 2009). It is also present in Coelophysis (Downs, 2000), Megapnosaurus (Downs, 2000) and "M." kayentakatae (Tykoski, 1998).

24. squamosal, ventral process a slender prong 3 or more times basal width.
This is actually present in Silesaurus (Dzik and Sulej, 2007), Lesothosaurus (Sereno, 1991), Saturnalia (Langer and Benton, 2006), "M." kayentakatae (Tykoski, 1998) and Coelophysis (Colbert, 1989). It is polymorphic in Sauropodiformes because one of Martinez et al.'s two examplars (Massospondylus- Sues et al., 2004) lacks it. The condition in Megapnosaurus is unknown (Raath, 1977).

45. dentary tooth 1 inset.
Oddly, silesaurids are coded as inapplicable, even though this is one of their distinctive characters. If anything ornithischians should be coded unknown, in case their predentary is homologous to the anterior dentary.

43. maxillary and dentary crowns lanceolate.
As noted above, there's no difference between Martinez et al.'s triangular and lanceolate shapes, as can be seen by the near identical shape of the supposed triangular tooth of Silesaurus (Dzik, 2003 fig. 5H) and the supposed lanceolate tooth of Panphagia (Martinez and Alcober, 2006 fig. 5B).

69. deltopectoral crest 45% or more of humeral length.
Eoraptor's crest has previously been reported to be 35% of humeral length (Langer and Benton, 2006). Note that in this and other cases where I claim Martinez et al.'s codings for Eoraptor are incorrect, it's with the caveat that they are redescribing the taxon and may be shown to be right with the publication of their monograph. Genasaurs' should be polymorphic, since Scutellosaurus (Colbert, 1964) has a short crest. Ceratosaurus also has a short crest (Galton, 1982).

76. manus phalanx I-1, rotation of axis through distal condyles 45° ventromedially.
Martinez et al.'s own figure only labels Eoraptor's torsion as 35 degrees.

79. preacetabular process subtriangular.
As noted above "strap-shaped" should be deleted and the taxa coded to reflect their distal shape, not their length. In that case, Heterodontosaurus' is tab-shaped (Santa Luca, 1980), Lesothosaurus' is broken (Thulborn, 1972; Sereno, 1991) and Genasauria's is rounded (Colbert, 1964; Galton, 1974). Panphagia's is also broken (Martinez and Alcober, 2009), while Saturnalia's is tab-shaped (Langer, 2003). Staurikosaurus' is rounded (Bittencourt and Kellner, 2009). Among theropods, Megapnosaurus' is tab-shaped (Raath, 1990), "M." kayentakatae's is unpreserved (Tykoski, 1998), Dilophosaurus' is tab-shaped (Tykoski, 2005) and Ceratosaurus' is unpreserved (Gilnmore, 1920).

81. preacetabular process, attachment scar present.
Also present in Marasuchus (Novas, 1996), Saturnalia (Langer, 2003), Herrerasaurus (Novas, 1993), Staurikosaurus (Bittencourt and Kellner, 2009). Absent in Sauropodiformes (Cooper, 1981; Huene, 1926). Unknown in "M." kayentakatae (Tykoski, 1998) and Ceratosaurus (Gilmore, 1920).

90. ischial mid shaft cross-sectional shape subtriangular.
This is absent in Panphagia (Martinez and Alcober, 2009). It is also present in Lesothosaurus (Thulborn, 1972), Herrerasaurus (Langer, 2003) and "M." kayentakatae (Tykoski, 1998).

122. astragalus fibular facet, primary orientation lateral.
The condition in Lagerpeton (Sereno and Arcucci, 1993) and Lesothosaurus (Thulborn, 1972) is unknown. Genasauria (Scutellosaurus- Langer and Benton, 2006) and Herrerasaurus (Langer and Benton, 2006) have a laterally oriented facet. Megapnosaurus (Langer and Benton, 2006) and "M." kayentakatae (Tykoski, 2005) lack it.

125. astragalus anteromedial corner shape (dorsal view)- anteriorly projecting at least 25% width of the medial side of the astragalus.
Martinez and Alcober (2009) state this is absent in Eoraptor. It's present in Megapnosaurus (Langer and Benton, 2006), "M." kayentakatae (Tykoski, 2005) and Dilophosaurus (Tykosaki, 2005). The condition in Lesothosaurus (Thulborn, 1972) is unknown.

Additionally, Martinez et al. found Eoraptor to be closer to Panphagia and Saturnalia than sauropodiforms based on-

83. ventral acetabular flange of ilium present.
Lesothosaurus lacks a flange (Sereno, 1991).

88. brevis fossa an arched ventrally-opening ovate or parallel-sided depression.
This was discussed above as being a composite character and miscoded in the outgroup (also in Staurikosaurus- Bittencourt and Kellner, 2009). Regardless, Eodromaeus has the same state as Eoraptor, so the combination is not unexpected in a basal theropod.

95. ischial antitrochanter, anteroposterior length less than adjacent length of the articular surface for the ilium (also in coelophysoids).
This is actually absent in Panphagia (Martinez and Alcober, 2009), Saturnalia (Langer, 2003), Coelophysis (Padian, 1986), Megapnosaurus (Raath, 1990), "M." kayentakatae (Tykoski, 2005) and Dilophosaurus (Tykoski, 2005). This is also present in Lagerpeton (Sereno and Arcucci, 1993, coded inapplicable by Martinez et al.), Heterodontosaurus (Santa Luca, 1980), Herrerasaurus (Novas, 1993) and Staurikosaurus (Bittencourt and Kellner, 2009). Makes me wonder if Martinez et al. reversed the states on accident. Silesaurus (Dzik, 2003), Lesothosaurus (Sereno, 1991), Genasauria (Colbert, 1964) and Tawa (Nesbitt et al., 2009) do not seem to have significant ischial antitrochanters.

When all of the above are changed in the matrix, Eoraptor is the basalmost theropod. An additional question to ask is how many previously suggested theropod characters of Eoraptor are in the matrix? In particular, how many of the characters suggested to link it with Tawa+Avepoda are included? As listed in the Database, the previously suggested characters are as follows. Those included in Martinez et al.'s matrix are in bold.

Tykoski (2005)- subnarial process of premaxilla narrow and rod-like; maxilla anterodorsally concave; nasal contacts antorbital fossa; lacrimal inverted L-shape; lacrimal at least equal to orbital height and reaches orbit's ventral rim; antorbital fossa exposure on lacrimal large, with triangular fossa on ventral process; vertebra 25 (dorsosacral) incorporated into sacrum (not actually present in Eoraptor, contra Tykoski); humerus twisted; metacarpal I distal condyles strongly asymmetrical; preacetabular process thin and blade-like; postacetabular process longer than acetabulum (not actually present in Eoraptor- Ezcurra, 2010); pubic fenestra (incorrectly coded absent in Eoraptor); distal ischium <3 times minimum width of shaft; subrectangular distal tibia with posterolateral extension (incorrectly coded absent in Eoraptor).
Ezcurra (2006)- lateral surface of premaxillary body pierced by a single neurovascular foramina above the second premaxillary tooth; maxillary antorbital fossa rostral to internal antorbital fenestra broad and rostrocaudally well extended; medial wall of the antorbital fossa extends through the entire ventral border of the internal antorbital fenestra as a very narrow lamina; lateral lamina of bone of the lacrimal with no interruption of the lacrimal antorbital fossa and restricted to the caudal margin of the ventral ramus along its dorsoventral extension; rostral process of jugal excluded from the internal antorbital fenestra, bluntly squared rostrally; ventral process of the squamosal length forms more than half of the caudal border of the infratemporal fenestra (absent in Eoraptor); humerus length subequal or shorter than 0.6 of the length of the femur; extensor pits on the dorsal surface of the distal end of metacarpals deep, well developed; shaft of metacarpal IV in relation to that of metacarpals I-III significantly narrower (incorrectly coded absent in Eoraptor); metacarpal IV and fourth digit: proximal portion set lateral to Mc III (idem Mc V) and with only one or lacking phalanges; supraacetabular crest and lateroventral border of the postacetabular process (lateral brevis shelf) continuous as a weakly developed ridge; cnemial crest on proximal tibia moderately developed; caudal cleft between medial part of the proximal end of the tibia and fibular condyle present.
Nesbitt et al. (2009)- premaxilla-maxilla, subnarial gap between the elements (absent in Eoraptor); nasal possesses a posterolateral process that envelops part of the anterior ramus of the lacrimal; ilium, ischiadic peduncle orientation well expanded posteriorly to the anterior margin of the postacetabular embayment.
Ezcurra (2010)- posterior part of premaxillary alveolar margin edentelous, resulting in an interruption of the upper tooth row (absent in Eoraptor); anterior margin of maxillary antorbital fossa squared; dorsoventrally compressed ridge on lateral surface of maxilla, forming the ventral border of the antorbital fossa (alveolar ridge) (incorrectly coded absent in Eoraptor); orientation of the lacrimal orbital margin erect and close to vertical; supraacetabular crest of ilium flares lateroventrally to form a hood-like overhang that hides anterodorsal half of acetabulum in lateral view (coded absent in Eoraptor); well developed brevis fossa with sharp margins on the ventral surface of the postacetabular process of the ilium present, being directly ventrally facing; well developed tibiofibular crest on distal femur.

Of course some of these are only supportive of a theropodan Eoraptor given the proper outgroup/ingroup arrangement and some are absent in Eoraptor, showing their own matrices have problems. But of the 31 characters present (as far as I can tell) in Eoraptor, only 11 are included, and of those 11 at least 4 are incorrectly coded as absent. Enforcing a placement for Eoraptor closer to avepods than herrerasaurids in this modified matrix is 13 steps longer, but the you have to wonder how many of the proposed characters for placing Eoraptor outside Herrerasaurus+Avepoda were included and how correctly they are coded. It's all outside the scope of this post.

In the end, I don't think the evidence for placing Eoraptor in Sauropodomorpha is strong. Of the 12 characters, 4 seem absent in Eoraptor, 2-3 of the others seem present basally in avepods, 3 of the others are present in Herrerasaurus, and all have high homoplasy. Even the toothless dentary tip and lanceolate teeth are complicated by their presence in silesaurids and/or ornithischians. With so much homoplasy among basal dinosauromorphs, it's necessary to include fragmentary but important taxa like Lewisuchus, Guaibasaurus, Chindesaurus and Pisanosaurus. Only then and when we incorporate all suggested conflicting character data can we hope to have meaningful results.

Martinez, Sereno, Alcober, Columbi, Renne, Montanez and Currie, 2011. A basal dinosaur from the dawn of the dinosaur era in Southwestern Pangaea. Science. 331, 206-210.

The Sauropodomorph Database is online!

2011-03-26T01:24:00.000-07:00

Go check it out, in its bare bones form. As for me, I'm getting some sleep...

The Sauropodomorph Database Approacheth- "Yibinosaurus" and "Sugiyamasaurus"

2011-03-21T22:09:00.000-07:00

The Sauropodomorph Database is almost ready to debut, but first here's a couple more entries to illustrate why I'm making the website. The first is "Yibinosaurus", whose usual online information is limited to what Olshevsky wrote on the DML in 2001. The other is "Sugiyamasaurus", which no one seems to have connected to Fukuititan yet.

"Yibinosaurus" Ouyang vide anonymous, 2001
"Y. zhoui" Ouyang vide anonymous, 2001
Toarcian, Early Jurassic
Dongyuemiao Member of Ziliujing Formation, Sichuan, China
Material- (Chongqing Museum of Natural History coll.) specimen including dorsal vertebrae
Comments- This name originally appeared in a guidebook, with the taxon stated to be under study by Ouyang. Ouyang (2003) later mentioned it in his thesis as a new genus, which he places in an eponymous subfamily within Vulcanodontidae. As he also includes the more basal Gongxianosaurus in Vulcanodontidae, Ouyang's conception of the family may be more of a grade. Ouyang further notes the anterior dorsal neural spines are transversely expanded, which he believes indicates a possible relationship to taxa with bifurcated spines like Datousaurus. As Ouyang states "Yibinosaurus" is from the same locality as Gongxianosaurus, the dorsal vertebrae, 51 articulated caudal vertebrae, scapulae and ilium mentioned by Luo and Wang (1999) as Gongxianosaurus sp. nov. may be the "Yibinosaurus" material.
References- Luo and Wang, 1999. New discovery on dinosaur fossils from Early Jurassic, Sichuan, China. Chinese Science Bulletin. 44(23), 2182-2188.
Anonymous, 2001. Dinosaur Fossils from Chongqing Natural History Museum.
Ouyang, 2003. Skeletal characteristics of Mamenchisaurus youngi and the systematics of mamenchisuarids. PhD thesis. Chengdu University of Technology. 176 pp.

Titanosauriform tooth (FPDM coll.) from the Kitadani Formation, probably Fukuititan and/or "Sugiyamasaurus". Scale = 10 mm. After Goto et al. (2002).

Fukuititan Azuma and Shibata, 2010
?= "Sugiyamasaurus" Lambert, 1990
F. nipponensis Azuma and Shibata, 2010
Barremian, Early Cretaceous
Kitadani Formation of the Akaiwa Subgroup of the Tetori Group, Japan
Holotype- (FPDM V8468) three teeth, incomplete cervical neural arch, three distal caudal vertebrae (30 mm), proximal scapula, incomplete humeri (~910 mm), incomplete radii (~600 mm), metacarpal IV (295 mm), incomplete ischia, partial femur (~1.14 m), partial tibia, fibula, pedal phalanx (130 mm), fragments
Referred- ?(Sugiyama-ryu; "Sugiyamasaurus") three teeth (Azuma, 1991)
? five teeth (Azuma, 1991)
?(FPDM 1080417) tooth (Goto et al., 2002)
?(FPDM 1080417-A) tooth (Goto et al., 2002)
?(FPDM 1080757) tooth (Goto et al., 2002)
?(FPDM 1080920) tooth (Goto et al., 2002)
?(FPDM 1080942) tooth (Goto et al., 2002)
?(FPDM 1080944) tooth (Goto et al., 2002)
Diagnosis- (after Azuma and Shibata, 2010) tooth crowns asymmetrical and elongated with weak or absent labial groove and no lingual concavity; stalk-like cervical epipophyses; humerus proximal width 32% of length; metacarpal IV 48% of radial length; ischia slightly expanded distally.
Comments- The holotype was discovered in 2007 and described as a basal titanosauriform, though it has yet to be included in an analysis.
Teeth were first discovered from the quarry in 1989. Three teeth were informally called "Sugiyama-ryu", as found in Azuma (1991) and referred to Camarasauridae by this author and Dong et al. (1990). Lambert (1990) inappropriately made it into a genus name, listing it as "Sugiyamasaurus" in a childrens' book. Azuma (1991) lists five additional sauropod teeth as family indet. A and B, but he later (2003) placed all the teeth in Brachiosauridae. Kobayashi et al. (2006) referred the specimens to Titanosauriformes indet. based on near identical morphology to teeth from the Kuwajima Formation. Goto et al. (2002) illustrate a tooth. As the "Sugiyamasaurus" teeth are generally similar to Fukuititan's in morphology (D-shaped section; wrinkled enamel; parallel mesial and distal edges- Kobayashi et al., 2006) and found in the same quarry, they may belong to the same taxon. They should be examined for Fukuititan's supposed dental autapomorphies, which should be checked for positional variation and compared to other taxa as well.
References- Dong, Hasegawa and Azuma, 1990. The Age of Dinosaurs in Japan and China. Fukui, Japan: Fukui Prefectural Museum. 65 pp.
Lambert, 1990. The Dinosaur Data Book. New York: Avon Books, 66. ISBN 0-380-75896-3.
Azuma, 1991. Early Cretaceous Dinosaur Fauna from the Tetori Group, central Japan. Research on Dinosaurs from the Tetori Group (1). Professor S. Miura Memorial Volume, 55-69.
Azuma, Kawagoshi and Miyagawa, 1995. Dinosaurs of the Tetori Group in Japan. Fukui Prefectural Museum. 158 pp.
Azuma and Tomida, 1995. Early Cretaceous dinosaur fauna of the Tetori Group in Japan. in Sun and Wang (eds.). Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers. China Ocean Press, Beijing. 125-131.
Goto, Yabe and Sano, 2002. The research report of the Dinosaur Fossil Exploratory Excavation held by Fukui Prefecture in 2001. Memoir of the Fukui Prefectural Dinosaur Museum. 1, 102-118.
Azuma, 2003. Early Cretaceous vertebrates from Katsuyama City, Fukui Prefecture, Japan. Memoir of the Fukui Prefectural Dinosaur Museum. 2, 17-21.
Kobayashi, Manabe, Ikegami, Tomida and Hayakawa, 2006. Dinosaurs from Japan. in Lu, Kobayashi, Huang and Lee (eds.). Papers from the 2005 Heyuan International Dinosaur Symposium. Geological Publishing House, Beijing. 87-102.
Shibata and Goto, 2008. Report of the 3rd Dinosaur Excavation Project in Katsuyama, Fukui, 2007. Memoir of the Fukui Prefectural Dinosaur Museum. 7, 109-116.
Azuma and Shibata, 2010. Fukuititan nipponensis, a new titanosauriform sauropod from the Early Cretaceous Tetori Group of Fukui Prefecture, Japan. Acta Geologica Sinica. 84(3), 454-462.

Sauropodomorph phylogenetic analyses - The list

2011-03-19T03:40:00.000-07:00

The first step to starting your own analysis is compiling the data from past analyses. Here's all of the quantitative cladistic sauropodomorph analyses I know of, in chronological order, with the subsequent modifications listed indented afterwards. Ones I don't have copies of are in bold. If anyone has them, I'd be thankful for a pdf of course. A 'u' in front of the entry means the supporting matrix was not presented. Also, if there are any I missed, I'd love to know.

uYou, 1990 (SVP abstract)

You, 1993 (Diplodocus thesis)

Russell and Zheng, 1993 (Mamenchisaurus sinocanadorum)

Upchurch, 1993 (Sauropoda phylo thesis)

uUpchurch, 1995 (Sauropoda phylo)

Calvo and Salgado, 1995 (Limaysaurus)

uGauffre, 1995 (SVP abstract)

Gauffre, 1996 (new riojasaurid thesis)

Zheng, 1996 (Shunosaurus and Camarasaurus thesis)

Salgado et al., 1997 (titanosaur postcrania)

uKellner and Azevedo, 1999 (Gondwanatitan)

Upchurch, 1998 (Sauropoda phylo)

Upchurch, 1999 (Nemegtosauridae)

Upchurch and Martin, 2002 (Cetiosaurus)

Alifanov and Averianov, 2003 (Ferganasaurus)

Sander et al., 2006 (Europasaurus)

uWilson and Sereno, 1994 (SVP abstract)

Wilson and Sereno, 1998 (Sauropoda phylo)

Sereno, 1999 (Sauropoda)

Upchurch and Martin, 2002 (Cetiosaurus)

Sanz et al., 1999 (Lirainosaurus)

Sereno, 1999 (Prosauropoda)

Leal, 2001 (Unaysaurus thesis)

Barrett et al., 2005 (Lufengosaurus)

Barrett et al., 2007 (Yunnanosaurus)

Benton et al., 2000 (Thecodontosaurus)

Casanovas et al., 2001 (Losillasaurus)

Curry Rogers, 2001 (titanosaur thesis)

Curry Rogers, 2005 (Titanosauria)
Csiki et al., 2010 (Paludititan)

Mannion, 2010 (Mongolosaurus)

Curry Rogers and Forster, 2001 (Rapetosaurus)

O'Leary et al., 2004 (Mali titanosaur)

Smith et al., 2001 (Paralititan)

Hinic, 2002 (Massospondylus thesis)

Wilson, 2002 (sauropod phylo)

Barco Rodriguez, 2003 (Galveosaurus thesis)

Harris and Dodson, 2004 (Suuwassea)

O'Leary et al., 2004 (Mali titanosaur)

Rauhut et al., 2005 (Brachytrachelopan)

Barco et al., 2006 (Galveosaurus)

Ksepka and Norell, 2006 (Erketu)

Rauhut, 2006 (Canadon Calcareo brachiosaurid)

Remes, 2006 (Tornieria)

Sander et al., 2006 (Europasaurus)

You et al., 2006 (Huanghetitan)

Lovelace et al., 2007 (Supersaurus)

Lu et al., 2007 (Huanghetitan)

Rose, 2007 (Paluxysaurus)

Allain and Aquesbi, 2008 (Tazoudasaurus)

Canudo et al., 2008 (Tastavinsaurus)

Santucci, 2008 (Uberaba titanosaur)

Hocknull et al., 2009 (Australian titanosaurs)

Remes et al., 2009 (Spinophorosaurus)

Royo-Torres et al., 2009 (Turiasaurus)

Upchurch and Mannion, 2009 (Qingshan somphospondylan)

Wilson and Upchurch, 2009 (Euhelopus)

Carballido and Pol, 2010 (Amygdalodon)

Chure et al., 2010 (Abydosaurus)
Csiki et al., 2010 (Paludititan)

Ksepka and Norell, 2010 (Erketu)

Mannion, 2010 (Mongolosaurus)

Suteethorn et al., 2010 (Phuwiangosaurus)
Mateus et al., 2011 (Angolatitan)

Zaher et al., 2011 (Tapuiasaurus)

Calvo and Gonzalez Riga, 2003 (Rinconsaurus)

Gonzalez Riga, 2003 (Mendozasaurus)

Yates, 2003 (Pantydraco)

Leal et al., 2004 (Unaysaurus)

Sues et al., 2004 (Massospondylus)

Barrett et al., 2007 (Yunnanosaurus)

Yates and Kitching, 2003 (Antetonitrus)

Yates, 2004 (Anchisaurus)

uYates, 2004 (Gryponyx)

Barrett et al., 2005 (Lufengosaurus)

Fedak, 2006 (Nova Scotia massospondylid thesis)

Fedak and Galton, 2007 (Anchisaurus)

Kutty et al., 2007 (Indian taxa)

Upchurch et al., 2007 (Chinshakiangosaurus)

Lu et al., 2010 (Chuxiongosaurus)

Galton and Upchurch, 2004 (Dinosauria 2)

Barrett et al., 2005 (Lufengosaurus)

Royo-Torres et al., 2006 (Turiasaurus)

Barrett et al., 2007 (Yunnanosaurus)

Kutty et al., 2007 (Indian taxa)

Upchurch et al., 2007 (Chinshakiangosaurus)

Salgado et al., 2004 (Limaysaurus)

Upchurch et al., 2004 (Apatosaurus)

Upchurch et al., 2004 (Dinosauria 2)

Sander et al., 2006 (Europasaurus)

Santucci, 2008 (Uberaba titanosaur)

Upchurch and Mannion, 2009 (Qingshan somphospondylan)

Wilson and Upchurch, 2009 (Euhelopus)
Csiki et al., 2010 (Paludititan)

Mannion, 2010 (Mongolosaurus)
Mateus et al., 2011 (Angolatitan)

Gallina and Apesteguia, 2005 (Cathartesaura)

Harris, 2005 (Suuwassea thesis)

Harris, 2006 (Suuwassea)

Taylor and Naish, 2007 (Xenoposeidon)

You et al., 2008 (Daxiatitan)

Taylor, 2009 (Brachiosaurus)

Mo et al., 2010 (Liubangosaurus)
Taylor et al., 2011 (Brontomerus)

Bonaparte et al., 2006 (Ligabuesaurus)

Salgado et al., 2006 (Zapalasaurus)

Calvo et al., 2007 (Muyelensaurus)

Calvo et al., 2007 (Futalognkosaurus)
Csiki et al., 2010 (Paludititan)

Filippi et al., 2011 (Narambuenatitan)

Sereno et al., 2007 (Nigersaurus)
Fernandez-Baldor et al., 2011 (Demandasaurus)

Upchurch et al., 2007 (sauropodomorph phylo)

Martinez, 2009 (Adeopapposaurus)

Bandyopadhyay et al., 2010 (Barapasaurus)

Sekiya, 2010 (Xixiposaurus)

Sertich and Loewen, 2010 (Seitaad)

Yates et al., 2010 (Aardonyx)

Rowe et al., 2011 (Sarahsaurus)

Yates, 2007 (Eucnemesaurus)

Smith and Pol, 2007 (Glacialisaurus)

Yates, 2007 (Melanorosaurus)

Ezcurra, 2010 (Chromogisaurus)

Knoll, 2010 (Ignavusaurus)

Sertich and Loewen, 2010 (Seitaad)

Yates, 2010 (Anchisaurus)

Yates et al., 2010 (Aardonyx)
Pol et al., 2011 (Leonerasaurus)

Rowe et al., 2011 (Sarahsaurus)

Lang, 2008 (cetiosaur thesis)

Gonzalez Riga et al., 2009 (Malarguesaurus)

Hocknull et al., 2009 (Australian titanosaurs)

Carballido et al., 2011 (Chubutisaurus)

Gallina and Apesteguia, 2011 (Bonitasaura skull)

Whitlock, 2011 (Diplodocoidea)

Announcing The Sauropodomorph Database with Ultrasaurus

2011-03-17T02:11:00.000-07:00

This won't be a surprise to you who have followed my Zhao posts, but the Theropod Database is expanding. When I started the website back in 2004, Mike Keesey's Dinosauricon 2 was in the works so I didn't plan to cover other groups. But now there's really nowhere to go that has consolidated info on dinosaur taxa, e.g. if you wanted to find somphospondylan synapomorphies, a list of all Early Jurassic sauropods, or a material list for every taxon (well, Paleofile has the latter, but costs money). I've been keeping a basic list on my computer all these years, but it's time to update it and put it online. As with the ex-theropod portion of the site, it holds special interest for me because I'm unfamiliar with most of the data. It's also interesting because I'll be creating a sauropodomorph matrix to analyze all the taxa. Most valid Mesozoic theropod taxa have been included in at least one analysis, but I don't think that's true for sauropods, especially the many titanosaurs and basal camarasauromorphs. Nor have most actually been compared to each other, and there are several messy groups of species like Mamenchisaurus and Omeisaurus that I'd like to have an opinion of. The format will be the same as the theropod parts, though I'm not sure how it will be integrated yet. This month I've been creating the backbone of each page by listing the named clades with their definitions, and once that's done I'll upload the extremely partial first version. None of this means I'll be ignoring theropods of course, as they remain my main interest. Expect me to switch back and forth between my sub-interests as usual.

For a sample, here's the current Ultrasaurus entry. The phylogenetic relationships will be considered further once I have a better framework to use.

Ultrasaurus tabriensis holotype proximal humerus (DGBU-1973) in proximal (B) and anterior (C) views. Scale = 100 mm. After Lee et al., 1997.

Ultrasaurus Kim, 1983
= "Ultrasaurus" Kim, 1981
U. tabriensis Kim, 1983
Aptian-Early Albian, Early Cretaceous
Gugyedong Formation, South Korea
Holotype- (DGBU-1973) proximal humerus (435 mm wide)
Paratype- ?(DGBU coll.) caudal neural spine
Referred- ? rib fragments (Kim, 1988)
? cervical vertebra (Kim, 1988)
Comments- Discovered in 1977, initially identified as a sauropod femur or tibia (Chang et al., 1982) or a proximal brachiosaurid ulna (Kim, 1981, 1983). Paul (1988) notes it is actually a proximal humerus. All modern authors have considered it an indeterminate sauropod, though as Barrett et al. (2002) note, the absence of a well-developed proximolateral humeral process excludes it from Somphospondyli at least.
References- Kim, 1981. Cretaceous dinosaur fossils discovered from two dinosaur sites of Korea. Journal of the Geological Society of Korea. 17, 297.
Chang, Seo and Park, 1982. Occurrence of a dinosaur limb bone near Tabri, southern Korea. Journal of the Geological Society of Korea. 18, 195-202.
Kim, 1983. Cretaceous dinosaurs from South Korea. Journal of the Geological Society of Korea. 19(3), 115-126.
Kim, 1988. Excavations and studies of dinosaur skeletons of Korea. Abstracts at the Annual Meeting of the Paleontological Society of Korea. 4(2), 168-169.
Paul, 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world's largest dinosaurs. Hunteria. 2, 1-14.
Lee, 1997. Reassessment of Ultrasaurus tabriensis, Kim 1983 and the significance of Korean Sauropoda. Abstracts at the Annual Meeting of the Paleontological Society of Korea. pg 14.
Lee, Yang and Park, 1997. Sauropod dinosaur remains from the Gyeongsang Supergroup, Korea. Paleontological Society of Korea, Special Publication. 2, 103-114.
Barrett, Hasegawa, Manabe, Isaji and Matsuoka, 2002. Sauropod dinosaurs from the Lower Cretaceous of eastern Asia: Taxonomic and biogeographic implications. Palaeontology. 45, 1197-1217.

The Ornithischians- Zhao's nomina nuda part 8

2011-03-02T02:35:00.000-08:00

Well, that was a sad month post-wise. But the good news is that I got my part of the manuscript finished, so now we'll see how the submission goes. Here's a post to finish the Zhao series, dealing with his ornithischians. No illustrations are known for the undescribed taxa, and the relationships and post-description data aren't discussed for the four officially described genera. Sorry about the small text size below and oddly different formatting for Monkonosaurus- Blogger's terrible when it comes to pasting things from Word. The text looks large and identical in the compose window...

Coming up, the rest of the "suggested phylogenetic definitions" series and a (perhaps not so-)surprise announcement of a new section for the Database I've been working on.

"Tianchungosaurus" Zhao, 1983
Etymology- May have the same etymology as Dianchungosaurus, which refers to the Dianzhong Basin of Yunnan. Alternatively, Tianzhong would mean "in the fields", but the etymology remains uncertain since the name was not also written in Chinese by Zhao.
Early Jurassic
China
Comments- Stated to be a pachycephalosaur, but Zhao includes heterodontosaurids and ceratopsians in this group too. He referred it to his new superfamily Tianchungosauroidea, supposedly ancestral to other marginocephalians and including Heterodontosaurus (which would make the superfamily Heterodontosauroidea instead). Lambert (1990) believed it may be a misspelling of Dianchungosaurus (then thought to be a heterodontosaurid, since identified as a mesoeucrocodylian), which was also followed by Olshevsky (1991) and The Paleobiology Database.

Dianchungosaurus? "elegans" Zhao, 1985
Etymology- The species name means elegant.
Hettangian, Early Jurassic
Zhangjiawa Member of the Lufeng Formation, Dianchung, Yunnan, China
Comments- Zhao (1985) stated this was a heterodontosaur, and that chaoyangsaurids evolved from it. Chure and McIntosh (1989) place this in Pachycephalosauridae and mark this name as sic, perhaps indicating they believe it to be intended as "Tianchungosaurus". Similarly, Olshevsky (1991) notes it may be the intended type species of that genus.

I've kept the above entries separate to better reflect what is known and has been said about each name. It seems probable "Tianchungosaurus" and Dianchungosaurus? "elegans" refer to the same material, since the other new Jurassic taxa listed by Zhao (1983) are also mentioned in his 1985 paper, both are heterodontosaurs from the Early Jurassic of China, and D and T are similar sounds. It also seems probable "Tianchungosaurus" is the misspelling, since Zhao did name additional species of other previously named genera (e.g. Megalosaurus, Plesiosaurus, Ichthyosaurus) and two heterodontosaurs having such similar names is unlikely. What's more uncertain is if "elegans" is actually a heterodontosaurid or is a crocodylian like the type species of Dianchungosaurus is now known to be. Perhaps it is best placed in Archosauria incertae sedis for now.

"Changdusaurus" Zhang et al., 1982
"Changtusaurus" Zhao, 1983
"Changdusaurus laminaplacodus" Zhao, 1985
"Chendusaurus" Lambert, 1990
"Chengdusaurus" Lambert, 1990
"Changtusaurus laminaplacodus" Chure and McIntosh, 1989
"Changduosaurus laminaplacodus" Fang, Zhang, Lu, Han, Zhao and Li, 2006
Etymology- Changdu is a variant of Qamdo, the county the remains were found in. The species name refers to thin plates, presumably the dermal plates typical of stegosaurs.
Middle Jurassic
Middle Dapuka Group, Dabuka, Qamdo County, Tibet, China
Material- (~7 m) specimen seemingly including dermal plates, and probably ischia and femora
Comments- This was first announced by Zhang et al. (1982), who also gave its length. Zhao (1985) states that "transitional characters, as exemplified by the Middle Jurassic stegosaurs in Tibet" include flat ischia, a reduced fourth trochanter, and broad, thin dermal plates. These may thus be characteristics of "Changdusaurus". Lambert (1990) listed both "Chendusaurus" and "Chengdusaurus" as "perhaps Changdusaurus", but the original source of these variants is unknown. Glut (1997) incorrectly listed it as being Late Jurassic in age. Weishampel et al. (2004) list it as "undescribed ?stegosaur". Fang et al. (2006) indicated it derives from lower in the Dapuka Group than the other reported taxa. Based on the sequence of spellings, "Changdusaurus" is probably the intended one.
Relationships- Stated by Zhao (1983) to be an intermediate stegosauroid, it has been assigned to Stegosauridae by later authors (e.g. Chure and McIntosh, 1989; Olshevsky, 1991). Thin plates are only known in the Loricatosaurus+Stegosaurus clade, so may indicate "Changdusaurus" is a member. All stegosaurs have reduced fourth trochanters, though those of stegosaurids are absent. Ischial thickness is not currently used in stegosaur phylogenetics.
References- Zhang et al., 1982. The Roof of the World: Exploring the Mysteries of the Qinghai-Tibet Plateau. Harry N. Abrams Inc, New York. 227 pp.

Monkonosaurus lawulacus Zhao vide Dong, 1990
= "Monkonosaurus" Zhao, 1983
= "Monkonosaurus lawulacus" Zhao, 1986
= "Monkonosaurus lawulocus" Dong, 1987
= "Monkosaurus lawulacus" Chure and McIntosh, 1989
Etymology- Monko is a variant of Markam, the county it was discovered in. Lawulashan is the mountain the material was discovered on.
Early Cretaceous
Lura Formation, Laoran, Markam County, Tibet, China
Holotype- (IVPP coll.) (~5 m) two partial vertebrae (lost), sacrum (~311 mm), ilia (~905 mm), three dermal plates (lost)
Comments- The holotype was discovered in 1976 by a team from the Chinese Academy of Sciences, and originally referred to Zhao's (1983) new thyreophoran ("armatosaurian") superfamily Oligosacralosauroidea, distinguished by its lower number of sacrals than ankylosaurids (3-5, and indeed Monkonosaurus has 5). The superfamily is invalid as there is no genus "Oligosacralosaurus", and Monkonosaurus has since been universally referred to Stegosauridae. The taxon was eventually officially described by Dong (1990), and the iliosacral block has been photographed by Dong (1987) and Dong (1990). Note Dong (1990) is incorrect that Zhao used a species name for the taxon in 1983. Maidment and Wei (2006) redescribed the material and refigured the now broken iliosacral block, believing the taxon to be indeterminate, a conclusion Maidment repeated in 2010. Glut (1997) incorrectly credits the official name to Zhao, 1983/6.
References- Zhao, 1986. [unknown title] in Hao, Su, Yu and Li (eds.). The Cretaceous System of China. Stratigraphy of China. 12, 67-73.
Dong, 1987. Dinosaurs from China. Beijing: China Ocean Press. 114 pp.
Dong, 1990. Stegosaurs of Asia. in Carpenter and Currie (eds.). Dinosaur Systematics. Cambridge: Cambridge University Press. 255-268.
Maidment and Wei, 2006. A review of the Late Jurassic stegosaurs (Dinosauria, Stegosauria) from the People’s Republic of China. Geological Magazine. 143(5), 621-634.
Maidment, 2010. Stegosauria: A historical review of the body fossil record and phylogenetic relationships. Swiss Journal of Geosciences. 103, 199-210.

Polysacralosauroidea Zhao, 1983
Comments- Zhao's name for Ankylosauria. Note it is invalid due the absence of a genus "Polysacralosaurus".

Tianchisaurus nedegoapeferima Dong, 1993
= "Tenchisaurus" Dong, 1981
= "Sangonghesaurus" Zhao, 1983
= "Teinchisaurus" Dong, 1987
= "Jurassosaurus nedegoapeferkimorum" Dong vide Holden, 1992
= "Tianchisaurus" Dong, 1992
= Tianchiasaurus Dong, 1993
Etymology- Zhao's genus name refers to the Sangonghe Valley where the remains were discovered. Dong's genus name refers to Tianchi, the lake it was found near. The species name is a combination of letters from the beginning of the last names of the main actors of Jurassic Park.
Bathonian-Callovian, Middle Jurassic
Toutunhe Formation, Sangonghe Valley, Fukang County, Xinjiang, China
Holotype- (IVPP V10614) (~3 m) skull roof fragment, occipital condyle, fragmentary mandible, axis, third cervical centrum, fifth cervical centrum, seventh cervical centrum, first dorsal vertebra, third dorsal veertebra, sixth dorsal vertebra, ninth dorsal vertebra, tenth dorsal vertebra, eleventh dorsal vertebra, dorsal rib fragments, partial sacrum (61, 65, 64, 55, 55, 56, 45 mm), first caudal vertebra, second caudal vertebra, mid caudal vertebra, scapular fragment, humeral fragment, ilial fragment, incomplete femora, metatarsal II, metatarsal III, metatarsal IV, phalanx III-?, phalanx IV-? , many scutes, tail club
Comments- While Zhao (1983) only indicated "Sangonghesaurus" was a Middle Jurassic (presumably Chinese) ankylosaur, Olshevsky (online, 1997) is probably correct in suspecting it is what was later described as Tianchisaurus by Dong (1992). This is because Tianchisaurus was discovered in 1974 (by Xinjiang University students), sent to the IVPP in 1976 where Zhao worked, and was discovered in the Sangonghe Valley. It was assigned to Ankylosauridae by Olshevsky (1991) and Dong (1993).
References- Dong, 1981. Vertebrates: 400 million years of evolution in the Chinese continent. Part VI, Reptilia. Yokahama Dinosaur Exhibition. 30-55.
Dong, 1987. Dinosaurs from China. Beijing: China Ocean Press. 114 pp.
Dong, 1992. Dinosaurian Faunas of China. China Ocean Press (Beijing). 192 pp.
Holden, 1992. Paleontology's `Jurassic' windfall. Science. 258(5090), 1879.
Dong, 1993. An ankylosaur (ornithischian dinosaur) from the Middle Jurassic of the Junggar Basin, China. Vertebrata PalAsiatica. 31(4), 257-266.
Dong, 1994. Erratum. Vertebrata PalAsiatica. 32(2), 142.
Olshevsky, online 1997. http://dml.cmnh.org/1997Sep/msg00953.html

Chaoyangsauridae Zhao, Cheng, Xu and Makovicky, 2006
= "Chaoyoungosauroidea" Zhao, 1983
= "Chaoyoungosauridae" Lambert, 1983
Chaoyangsaurus youngi Zhao, Cheng and Xu, 1999
= "Chaoyoungosaurus" Dong, 1981
= "Chaoyoungosaurus liaosiensis" Zhao, 1985
= "Chaoyangosaurus liaosiensis" Dong, 1987
= "Chaoyangsaurus" Sereno, 1999
= Chaoyangosaurus youngi Weishampel, Barrett, Coria, Le Loeuff, Xu, Zhao, Sahni, Gomani and Noto, 2004
Etymology- Chaoyang is the county it was discovered in. The original species name refers to Liaoxi, a historical province in what is now Western Liaoning. The new species name refers to famed Chinese paleontologist Young Zhongjian.
Tithonian, Late Jurassic
Tuchengzi Formation, Ershijiazi, Chaoyang County, Liaoning, China
Holotype- (IGCAGS V371) partial skull, mandible, axis, six cervical vertebrae, proximal scapula, proximal humerus
Comments- This was discovered by Cheng in 1976 and eventually officially described by Zhao et al. (1999). The genus name was originally published by Dong (1981) in a Japanese guidebook. Dong (1992) incorrectly states it was described by Zhao and Cheng in 1983.
References- Dong, 1981. Vertebrates: 400 million years of evolution in the Chinese continent. Part VI, Reptilia. Yokahama Dinosaur Exhibition. 30-55.
Lambert, 1983. A Field Guide to the Dinosaurs. Avon Press. 256 pp.
Dong, 1987. Dinosaurs from China. Beijing: China Ocean Press. 114 pp.
Dong, 1992. Dinosaurian Faunas of China. China Ocean Press (Beijing). 192 pp.
Sereno, 1999. The evolution of dinosaurs. Science. 284(5423), 2137-2147.
Zhao, Cheng and Xu, 1999. The earliest ceratopsian from the Tuchengzi Formation of Liaoning, China. Journal of Vertebrate Paleontology. 19(4), 681-691.

Xuanhuaceratops niei Zhao, Cheng, Xu and Makovicky, 2006
= "Xuanhuasaurus niei" Zhao, 1985
= "Xuanhanosaurus niei" Chure and McIntosh, 1989
= "Xuanhuasaurus nieii" Weishampel, Barrett, Coria, Le Loeuff, Xu, Zhao, Sahni, Gomani and Noto, 2004
Etymology- Xuanhua is the county the material was found in, while the species name honors Nie Rongzhen, who gave the holotype to Zhao and Cheng.
Late Jurassic
Houcheng Formation, Yanjiagou, Xuanhua County, Hebei, China
Holotype- (IVPP V12722) (~1 m; adult) partial skull, partial mandibles, teeth, two cervical centra, dorsal neural arch, dorsal centra, partial sacrum, proximal caudal vertebra, incomplete scapula, partial coracoid, partial humeri (~40 mm), proximal ischium, proximal femur, partial tibia, proximal metatarsal I, proximal metatarsal II, proximal metatarsal III
Paratypes- (IVPP V14527) fragmentary skull, teeth and postcrania
(IVPP V14528) fragmentary skull, teeth and postcrania including atlantal intercentrum and astragalus
(IVPP V14529) partial jaws
Comments- The holotype was discovered in the 1970's and eventually officially described by Zhao et a. (2006). Note they incorrectly cite Zhao's 1983 paper as including the genus. The paratypes were discovered in 2003. Originally noted by Zhao (1985) as a "prototype psittacosaur" and thus presumably a chaoyangsaurid given his 1983 classification.
Reference- Zhao, Cheng, Xu and Makovicky, 2006. A new ceratopsian from the Upper Jurassic Houcheng Formation of Hebei, China. Acta Geologica Sinica. 80(4), 467-473.

"Megacervixosaurus" and Kunmingosaurus - Zhao's nomina nuda part 7

2011-02-22T00:38:00.000-08:00

Figure I have these things written, might as well post them. Today we finish off the sauropods. Remember the references not listed are in the first Zhao nomen nudum post.

"Megacervixosaurus" Zhao, 1983

"Megacervixosaurus tibetensis" Zhao, 1986
Etymology- The genus name refers to a large neck, while the species name refers to Tibet where the remains were found.
Late Cretaceous
Zonggu Formation, Zonggu, Markam County, Tibet, China
Material- specimen including cervical vertebrae
Comments- Zhao (pers. comm. in Molnar, 2011) noted similarity of its posterior cervicals to Austrosaurus.
Relationships- Stated by Zhao (1983) to be a homalosauropodoid, in which he includes peg-toothed taxa like diplodocoids and titanosaurs. Lambert (1990), Olshevsky (1991) and provisionally Glut (1997) listed it as a diplodocid. Olshevsky (online, 1999) also suggested it may be mamenchisaurid, perhaps based on the name, though Zhao did place Mamenchisaurus in Homalosauropodoidea too . Weishampel et al. (2004) questioningly listed it as a lithostrotian.
As no morphological data has been released on "Megacervixosaurus", its relationships must necessarily remain tentative. The absence of Cretaceous or Asian diplodocids renders that identification suspect, while mamenchisaurids are also unknown from the Cretaceous. Indeed, the only Late Cretaceous sauropods are rebbachisaurids and titanosaurs, and only the latter are known from East Asia. "Megacervixosaurus" is here considered a probable titanosaur.

References- Yang, 1986. The Cretaceous System. in Yang, Cheng and Wang (eds.). The Geology of China. Clarendon Press. 153-167.
Zhao, 1986. [unknown title] in Hao, Su, Yu and Li (eds.). The Cretaceous System of China. Stratigraphy of China. 12, 67-73.
Molnar, 2011. New morphological information about Cretaceous sauropod dinosaurs from the Eromanga Basin, Queensland, Australia. Alcheringa: An Australasian Journal of Palaeontology. DOI: 10.1080/03115518.2011.533978

Kunmingosaurus Zhao vide Dong, 1992
K. wudingensis Zhao vide Dong, 1992
= "Kunmingosaurus wudingi" Zhao, 1985
= "Kunmingosaurus utingensjs" Zhao, 1985
= "Kunmingosaurus utingi" Zhen, Li and Rao, 1986
= "Kunmingosaurus utingensis" Chure and McIntosh, 1989
= "Kunmingosaurus wudingensis" anonymous, 1990 vide Olshevsky, 1991
= Kunmingosaurus wusdingensis Weishampel, Barrett, Coria, Le Loeuff, Xu, Zhao, Sahni, Gomani and Noto, 2004
Etymology- Kunming is the capital city of Yunnan, while Wuding is the county and basin the specimen was found in.
Hettangian, Early Jurassic
Zhangjiawa Member of the Lufeng Formation, Hoshaofang, Wuding County, Yunnan, China
Holotype- (IVPP coll.) (~11 m) incomplete skeleton including dorsal vertebrae, eight proximal caudal vertebrae, four chevrons, ilium, pubis, femur (~847 mm), tibia, fibula, astragalus, metatarsal I, phalanx I-1, pedal ungual I, metatarsal II, phalanx II-1, pedal ungual II, metatarsal III, phalanx III-1, phalanx III-2, pedal ungual III, metatarsal IV, phalanx IV-1, metatarsal V, phalanx V-1
....(BNHM,PZGR 74) dentary
....(BNHM,PZGR 75) dentary
Referred- ?(FMNH CUP 2042) maxilla (Barrett, 1999)
?(IVPP coll.) tooth (Upchurch and Barrett, 2000)


Kunmingosaurus wudingensis holotype dentaries BNHM,PZGR 74 and 74 in medial (top) and lateral (bottom) views, with four teeth in labial and lingual views. After Young (1966).

Kunmingosaurus wudingensis holotype posterior skeleton (after Zhao, 1985).

Comments- The species name is spelled "wudingi" in the text, and "utingensjs" in the figure caption, which as noted by Chure and McIntosh (1989) are probably unintentional variants, and the latter no doubt a mispelling of "utingensis".
The skeleton was discovered by Su in 1954, but the dentaries were only discovered later in 1960 and described and illustrated by Young (1966) as specimens of Lufengosaurus magnus. Dong (1992) referred them to the same individual as the postcrania since they came from the same quarry. While Dong (and later Olshevsky, 2000) was incorrect in stating Zhao described the taxon in 1985, his own book contains a diagnosis, type and illustration so would seem to validate the nomenclature (contra Barrett, 1999). Indeed, Upchurch et al. (2004) attribute the name to Dong, 1992. A photo of part of the mounted skeleton is in Zhao (1985), contra Barrett (1999). Dong et al. (1990) published a photograph of the entire skeleton, and several are available online as well. Li et al. (2010) note Kunmingosaurus lacks dorsal pleurocoels and has a poorly developed fourth trochanter.
Simmons (1965) described a maxilla (FMNH CUP 2042) from Ta Ti in the same beds as Yunnanosaurus robustus, which is similar to Kunmingosaurus in having a sauropodan lateral plate and serrated, spatulate teeth with a lingual ridge. Barrett (1999) redescribed it as a sauropod maxilla, though he did not refer it to any genus. Upchurch and Barrett (2000) described a referred tooth.

Relationships- Stated by Zhao (1985) to be a primitive sauropod. Chure and McIntosh (1989) and Lambert (1990) listed it as a cetiosaurid, while Olshevsky (1991) listed it provisionally as a barapasaurid and Dong (1992) as a shunosaurine camarasaurid. Upchurch and Barrett (2000) discussed it as a 'vulcanodontid', which was a grade of basal sauropods in their scheme, and described a referred tooth. Upchurch (1995) noted there was no published evidence suggesting it was a vulcanodontid, however. He later (1998) noted that Kunmingosaurus' teeth were more plesiomorphic than Barapasaurus, Shunosaurus, Patagosaurus and other taxa in having only a shallow lingual concavity and being quite labiolingually compressed. Barrett (1999) considered the dentaries to be sauropod based on the dorsoventrally expanded symphysis and lateral plate. Fang et al. (2006) list it as a camarasaurid.
When entered into a modified version of Wilson's (2002) analysis, Kunmingosaurus emerges more derived than Chinshakiangosaurus, Antetonitrus, Lessemsaurus and Blikanasaurus but less than Shunosaurus and eusauropods (so is not a cetiosaurid, barapasaurid, shunosaurid or camarasaurid). It is thus related to taxa such as Gongxianosaurus, Kotasaurus, Spinophorosaurus, Tazoudasaurus and Vulcanodon, so may be considered vulcanodont-grade. Note the results agree with Upchurch's (1998) statements, though his dental characters were not used by Wilson. Specifically, Kunmingosaurus is more derived than Chinshakiangosaurus based on the D-shaped teeth and reduced fourth trochanter, but less derived than Shunosaurus based on no crown-to-crown occlusion, straight dorsal ilial margin and unreduced pedal phalanges.

References- Simmons, 1965. The non-therapsid reptiles of the Lufeng Basin, Yunnan, China. Fieldiana, Geology. 15, 1-93.
Young, 1966. On a new locality of the Lufengosaurus of Yunnan. Vertebrata PalAsiatica. 10(1), 64-67.
Zhen, Li and Rao, 1986. Dinosaur footprints of Jinnin, Yunnan. Memoirs of the Beijing Natural History Museum. 33, 19pp.
Dong, Hasegawa and Azuma, 1990. The Age of Dinosaurs in Japan and China. Fukui, Japan: Fukui Prefectural Museum. 65 pp.
Dong, 1992. Dinosaurian Faunas of China. China Ocean Press (Beijing). 192 pp.
Upchurch, 1995. The evolutionary history of sauropod dinosaurs. Philosophical Transactions of the Royal Society of London B. 349, 365-390.
Upchurch, 1998. The phylogenetic relationships of sauropod dinosaurs. Zoological Journal of the Linnean Society. 124, 43-103.
Barrett, 1999. A sauropod dinosaur from the Lower Lufeng Formation (Lower Jurassic) of Yunnan Province, People's Republic of China. Journal of Vertebrate Paleontology. 19(4), 785-787.
Martin-Rolland, 1999. Les sauropodes chinois [The Chinese sauropods]. Revue Paléobiologie, Genève. 18(1), 287-315.
Olshevsky, 2000. An Annotated Checklist of Dinosaur Species by Continent. Mesozoic Meanderings. 3, 157 pp.
Upchurch and Barrett, 2000. The evolution of sauropod feeding mechanisms. in Sues (ed.). Evolution of Herbivory in Terrestrial Vertebrates: Perspectives from the Fossil Record. Cambridge Press. 79-123.
Upchurch, Barrett and Dodson, 2004. Sauropoda. in Weishampel, Dodson and Osmolska (eds.). The Dinosauria: Second Edition. University of California Press. 259-322.
Li, Yang, Liu and Wang, 2010. A new sauropod from the Lower Jurassic of Huili, Sichuan, China. Vertebrata PalAsiatica. 48(3),185-202.

I'm still alive! And look- Megaraptor foot!

2011-02-16T22:45:00.000-08:00

Just wanted to reassure everyone I'm still here. I've been doing *gasp* actual work to be submitted, finishing off the last appendix of the manuscript. But in the absence of something else, here's a Photoshop rendition of Megaraptor's metatarsus using the holotype (metatarsal III, from Novas, 1998), MUCPv-341 (metatarsal IV, from Calvo et al., 2004) and UNPSJB-PV 958 (metatarsal II, from Lamanna, 2004). The individuals are almost the same size based on their manual unguals Is, so the metatarsals are at almost the same scale.

Composite metatarsus of Megaraptor in extensor view with metatarsal IV also in proximal view. Modified from Novas (1998), Calvo et al. (2004) and Lamanna (2004).

References- Novas, 1998. Megaraptor namunhuaiquii, gen. et sp. nov., a large-clawed, Late Cretaceous theropod from Patagonia. Journal of Vertebrate Paleontology. 18(1), 4-9.

Calvo, Porfiri, Veralli, Novas and Pobletei, 2004. Phylogenetic status of Megaraptor namunhuaiquii Novas based on a new specimen from Neuquén, Patagonia, Argentina. Ameghiniana. 41(4), 565-575.

Lamanna, 2004. Late Cretaceous dinosaurs and crocodiliforms from Egypt and Argentina. PhD Thesis. University of Pennsylvania. 305 pp.

If this were a scathing criticism of YOUR paper, would you want to be notified by me when I post it?

2011-01-29T13:47:00.000-08:00

Title says it all, based on this comment. I know some professionals read my blog, so I'd be interested to hear your opinion.

Do they even understand the matrix they're coding?

2011-01-28T00:52:00.000-08:00

You may remember my prior criticism of Hone and Benton (2008), who merged matrices when examining pterosaur relationships, but didn't combine equivalent OTUs. They had both Lepidosauromorpha AND the lepidosauromorphs Gephyrosaurus, Sphenodontia and Squamata. And they had both Choristodera AND the choristoderes Lazarussuchus, Cteniogenys and Champsosaurus. Disturbingly, each more inclusive OTU did not clade with its exemplars in their trees.

Well now we have another example of using matrices without taking equivalent OTUs into account. Yates (2004) had a sauropodomorph matrix where he tried two sets of outgroups. One was Herrerasaurus and (Neo)Theropoda, another was Ornithischia and an expanded Theropoda including Herrerasaurus. In the recent description of Chuxiongosaurus, Lu et al. (2010) used Yates' matrix but just ran the whole thing without noticing this. Thus we have a cladogram with "Neotheropoda" sister to "Theropods"... :| Herrerasaurus is the outgroup, probably because it is listed first in Yates' matrix, and Lu et al. didn't realize PAUP makes the first listed OTU the outgroup automatically. Thus Ornithischia (which really should be the outgroup) is sister to the double-theropod clade. What makes it especially sad is even if Lu et al. didn't read Yates' text, Yates labels the OTUs "Herrerasaurus ischigualastensis", "Theropoda (excluding Herrerasaurus)" and "Theropoda (including Herrerasaurus)" in his matrix. How can you copy codings from that and not realize those aren't all independant taxa?!

As an aside, I'd like to see Chuxiongosaurus compared to Yunnanosaurus and Jingshanosaurus. Thanks to Brad McFeeters for alerting me to this mess.

Coming soon, more Zhao taxa and part 2 of my recommended theropod clade definitions.

References- Hone and Benton, 2008. Contrasting supertree and total-evidence methods: the origin of the pterosaurs. Zitteliana. 28, 35-60.

Lu, Kobayashi, Li and Zhong, 2010. A new basal sauropod dinosaur from the Lufeng Basin, Yunnan Province, Southwestern China. Acta Geologica Sinica. 84(6), 1336-1342.

Yates, 2004. Anchisaurus polyzelus (Hitchcock): The smallest known sauropod dinosaur and the evolution of gigantism among sauropodomorph dinosaurs. Postilla. 230, 58 pp.

"Damalosaurus" - Zhao's nomina nuda part 6

2011-01-20T09:33:00.000-08:00

Following along our survey of Zhao's sauropods, note he originally spelled this one with an 'o', unlike most subsequent authors.

"Damalosaurus" Zhao, 1983
"Damalasaurus laticostalis" Zhao, 1985
"Damalasaurus magnus" Zhao, 1985
= "Damalosaurus laticostalis" [sic] Chure and McIntosh, 1989
= "Damalosaurus magnus" [sic] Chure and McIntosh, 1989
= "Damalasaurus magnas" [sic] Zhang and Li, 1997
Etymology- Named for Damala Mountain in Qamdo, with the species referring to wide ribs (laticostalis) or large size (magnus).
Early Jurassic
Middle Daye Group, Daye, Qamdo County, Tibet, China
Material- (~15 m) specimen including dorsal rib
Comments- The species is listed as "magnus" in the text, but "laticostalis" in the plate caption. Olshevsky (1991) listed "laticostalis as the type, though I consider it probable only one species is intended by Zhao since two are never present in faunal lists together (Zhao and Cheng, 1985; Zhang and Li, 1997; Fang et al., 2006). Fang et al. use "laticostalis" for the species, suggesting it is the intended one since Zhao is a coauthor. Zhao (1985) includes a photograph of a dorsal rib in situ, which the length estimate above is taken from assuming proportions like Barapasaurus. Glut (1997) incorrectly stated it is Middle Jurassic in age. Weishampel et al. (2004) list this as an undescribed sauropod in their faunal list.

Dorsal rib of "Damalosaurus laticostalis/magnus" in matrix, from Zhao (1985).

Relationships- Stated by Zhao (1983, 1985) to be a primitive sauropod. Chure and McIntosh (1989) listed it as a cetiosaurid, while Lambert (1990) and Olshevsky (1991) listed it as a brachiosaurid. Glut (1997) only listed it as Sauropoda incertae sedis. Fang et al. (2006) place it in Cetiosauridae, noting again it's a primitive sauropod. As those authors placing it in Brachiosauridae have never seen the specimen, and brachiosaurids are currently unknown from Asia or the Early Jurassic, that assignment seems less likely. Since Cetiosauridae is currently viewed as a grade of basal eusauropods, "Damalosaurus" is here placed as Sauropoda incertae sedis.

"Oshanosaurus" - Zhao's nomina nuda part 5

2011-01-18T10:00:00.000-08:00

"Oshanosaurus youngi" Zhao, 1985
Etymology- Oshan is a variant of Eshan, a county in Yunnan it was found in. The species name probably references famed Chinese paleontologist Young Zhongjian.
Hettangian, Early Jurassic
Zhangjiawa Member of the Lufeng Formation, Dianchung, Eshan County, Yunnan, China

Holotype anterior mandible of Eshanosaurus deguchiianus (IVPP V11579) in medial (A), dorsal (B) and lateral (C) views, and tooth in lingual (D), labial (E) and distal (F) views (after Xu et al., 2001). Is this "Oshanosaurus youngi"?

Comments- Glut (1997) incorrectly stated it was found in Mongolia. I suspect this is an old name for Eshanosaurus, which has the same etymology, is also from the Dianzhong Basin of Eshan County, was discovered by Zhao in 1971 and was later described in part by him (Zhao and Xu, 1998; Xu et al., 2001).
Relationships- Stated by Zhao (1985) to be a primitive sauropod. Chure and McIntosh (1989), Lambert (1990) and provisionally Olshevsky (1991) listed it as a cetiosaurid. Glut (1997) listed it as a possible heterodontosaurid or "geranosaur", possibly because Zhao mentions it in the same sentence as Dianchungosaurus. As traditional Cetiosauridae now refers to a grade of basal eusauropods, ignoring the Eshanosaurus connection I would retain "Oshanosaurus" as Sauropoda incertae sedis.
While Eshanosaurus is corrently believed to be a therizinosaur, therizinosaur mandibles are quite similar to those of sauropodomorphs and were poorly known in the 1980s. Indeed, Eshanosaurus' mandible resembles those of basal eusauropods (e.g. Shunosaurus) more than basal sauropodomorphs in having a dorsoventrally expanded symphysis, anterior teeth the largest, a basolingual swelling on its teeth, a lingual median ridge on its teeth, and tooth roots expanded to be broader than their crowns. However, it is unlike eusauropods in having a narrow symphysis, smooth enamel, a lateral dentary ridge and perpendicular serrations on its teeth. Given Eshanosaurus' similar incongruity when considered as a therizinosaur (more derived than the much later Falcarius in having a decurved symphysis, lateral ridge and enlarged serrations; not to mention early appearence compared to other coelurosaurs), it may be convergent with both eusauropods and therizinosaurs.

References- Zhao and Xu, 1998. The oldest coelurosaurian. Natrure. 394, 234-235.
Xu, Zhao and Clark, 2001. A new therizinosaur from the Lower Jurassic Lower Lufeng Formation of Yunnan, China. Journal of Vertebrate Paleontology. 21(3), 477-483.

"Lancangosaurus" - Zhao's nomina nuda part 4

2011-01-09T20:02:00.000-08:00

As always, general references are in the first post of the series.

"Lancangosaurus" Zhao, 1980
"Lancanjiangosaurus" Zhao, 1983
"Lancangjiangosaurus cachuensis" Zhao, 1985
"Lancanjiangosaurus cachuensis" Chure and McIntosh, 1989
"Lancanjiangosaurus cahuensis" Glut, 1997
"Lancanjiangosaurus cashuensis" Martin-Rolland, 1999
"Lanchangjiangosaurus cachuensis" Fang, Zhang, Lu, Han, Zhao and Li, 2006
Etymology- The genus references the Lancang Jiang, the local name for the head of the Mekong River. The species name refers to the Zaqu River, which is the upper reaches of the Mekong.
Middle Jurassic
Middle Dapuka Group, Dabuka, Qamdo County, Tibet, China
Material- (~15 m) specimen including skull, mandible, twelve teeth and limb elements
specimen (Fang et al., 2006)

Teeth of "Lancangosaurus" (after Zhao, 1985).

Comments- Though usually believed to be a preliminary name for Datousaurus (e.g. Olshevsky, 1991), "Lancangosaurus" was first reported by Zhao (1980) in relation to a Dapuka specimen, not the Xiashaximiao Datousaurus. Listed characters are large skull, large spatulate teeth which decrease gradually in size posteriorly, a thick mandible and robust limbs. Dong et al. (1983) believed the teeth were congeneric with those from the Wujiaba Quarry of the Shangshaximiao Formation, which they described as belonging to Omeisaurus junghsiensis and O. fuxiensis. Zhao (1985) figures teeth in situ, though the photograph is unclear. Note Olshevsky (1991) switched the authorship for the variants "Lancanjiangosaurus" and "Lancangjiangosaurus". Glut (1997) incorrectly listed it as being Late Jurassic in age. Fang et al. (2006) note additional material from lower in the same formation. Given the etymology, either "Lancangosaurus" or "Lancangjiangosaurus" would be the most accurate names.
Relationships- "Lancanjiangosaurus" was stated by Zhao (1983) to be a bothrosauropodoid, in which he includes spatulate-toothed taxa like camarasaurids and brachiosaurids. Zhao (1985) notes it is a sauropod similar to Cetiosaurus. Chure and McIntosh (1989) listed it as a cetiosaurid, as does Olshevsky (1991) provisionally, while Lambert (1990) listed it as a brachiosaurid. Glut (1997) merely referred it to Sauropoda incertae sedis. Most recently, Fang et al. (2006) place it in Cetiosauridae. The known characters are found in both basal eusauropods like Omeisaurus and camarasaurids, though the age, locality and Zhao's opinion all favor the former identification. Whether Dong et al. are correct in placing it close to Omeisaurus is unknown, and for now I recommend keeping it as Eusauropoda incertae sedis.
References- Zhao, 1980. [Mesozoic vertebrate-bearing beds and stratigraphy of northern Xinjinag: Report of Paleontological Expedition to Xinjiang IV.] Memoirs of the Institute of Vertebrate Palaeontology and Palaeoanthropology, Academia Sinica A. 15, 1-119.
Dong, Zhou and Zhang, 1983. [Dinosaurs from the Jurassic of Sichuan]. Palaeontologica Sinica, New Series C. 162(23), 1-136 .
Martin-Rolland, 1999. Les sauropodes chinois [The Chinese sauropods]. Revue Paléobiologie, Genève. 18(1), 287-315.

"Microdontosaurus" - Zhao's nomina nuda part 3

2011-01-09T01:49:00.000-08:00

"Microdontosaurus" Zhao, 1983
"Microdontosaurus dayensis" Zhao, 1985
Etymology- The genus name refers to small teeth, while the species name references the Daye township in Qamdo.
Middle Jurassic
Middle Dapuka Group, Dabuka, Qamdo County, Tibet, China
Material- specimen seemingly including teeth
Comments- As Gilmore (1902) already named an ichthyosaur Microdontosaurus petersonii (currently a junior synonym of Baptanodon discus), Zhao's sauropod will need a new name if it is officially described in the future. Glut (1997) incorrectly dates the species to 1983 and places it in the Late Cretaceous.
Relationships- Stated by Zhao (1983) to be a homalosauropodoid, in which he includes peg-toothed taxa like diplodocoids (including mamenchisaurids in his view) and titanosaurs. Similarly, Zhao (1985) states it is a primitive peg-toothed sauropod. Chure and McIntosh (1989) listed it as a cetiosaurid, Lambert (1990) listed it as a diplodocid, and Olshevsky (1991) as a melanorosaurid. Glut (1997) merely refers it to Sauropoda incertae sedis. Most recently, Fang et al. (2006) place it in Brachiosauridae.
A placement outside of Sauropoda is unlikely for a Middle Jurassic taxon (though not unheard of- see Yunnanosaurus? youngi), suggesting Olshevsky's assignment is incorrect. While traditionally only diplodocoids and titanosaurids were seen as having nonspatulate teeth, they are also found in more basal brachiosaur-grade titanosauriforms and even some basal eusauropods like Shunosaurus. This suggests Fang et al.'s assignment to Brachiosauridae may be most accurate, especially as Zhao is a coauthor while Chure, McIntosh and Lambert have not seen the specimen. Since Brachiosauridae as traditionally conceived is paraphyletic, "Microdontosaurus" is here tentatively assigned to Titanosauriformes incertae sedis.
References- Gilmore, 1902. Discovery of teeth in Baptanodon, an ichthyosaurian from the Jurassic of Wyoming. Science. 16(414), 913-914.

The Sauropodomorph Database Blog? Yates' analysis

2011-01-08T07:20:00.000-08:00

This will be a crazy month for the Theropod Database Blog, with a comparative lack of theropods. As part of my study of "Dachongosaurus", I examined Yates' (2007) matrix to see which characters it had. That analysis has been modified and added to by several authors, so I combined all of these changes to make the new version as most recently published. This involved-

Adding the 8 characters from the Glacialisaurus description (Smith and Pol, 2007).
Adding the 17 characters from the Chromogisaurus description (Ezcurra, 2010), modifying 215 and 221 (but not 245, 251 or 256), and changing many codings for basal taxa according to that paper.
Changing a few character descriptions and codings (mostly for Yunnanosaurus' skull and Tazoudasaurus' redescription) from Yates et al. (2010). This meant changing a miscoded state for Seitaad too.
Changing Anchisaurus' codings from Yates (2010).
Adding Aardonyx (Yates et al., 2010), Adeopapposaurus (Sertich and Loewen, 2010), Chromogisaurus (Ezcurra, 2010), Glacialisaurus (Smith and Pol, 2007), Gryponyx (Yates et al., 2010), Ignavusaurus (Knoll, 2010), herrerasaurid MACN PV-18649a (Ezcurra, 2010), Panphagia (Ezcurra, 2010) and Seitaad (Sertich and Loewen, 2010).

Because these have never been combined before, and could lead to a unique topology, I ran the matrix in PAUP. The strict consensus is-

|--Euparkeria
`--+--Crurotarsi
   `--+--Marasuchus
      `--+--Silesaurus
         `--Dinosauria
            |--Ornithischia
            `--Saurischia
               |--Herrerasauridae
               | |--Herrerasaurus
               | |--MACN PV-18649a
               | `--Staurikosaurus
               `--Eusaurischia
                  |--Theropoda
                  | |--Chindesaurus
                  | `--+--Eoraptor
                  |     `--Avepoda
                  `--Sauropodomorpha
                     |--Agnosphitys
                     |--Guaibasaurus
                     |--Panphagia
                     |--+--Chromogisaurus
                     | `--Saturnalia
                     `--+--Thecodontosaurus
                        |--Pantydraco
                        `--+--Efraasia
                           `--+--Ignavusaurus
                              `--+--Plateosauravus
                                 `--+--Ruehleia
                                    `--Plateosauria
                                       |--Prosauropoda/Plateosauridae
                                       | |--Unaysaurus
                                       | `--+--Sellosaurus
                                       |     `--+--Gresslyosaurus
                                       |        `--Plateosaurus
                                       `--Massopoda
                                          |--Riojasauridae
                                          | |--Eucnemesaurus
                                          | `--Riojasaurus
                                          `--+--Massospondylidae
                                             | |--+--Coloradisaurus
                                             | | `--+--Lufengosaurus
                                             | |     `--Glacialisaurus
                                             | `--+--Gryponyx
                                             |     `--+--Massospondylus
                                             |        `--+--Adeopapposaurus
                                             |           `--Seitaad
                                             `--+--Yunnanosaurus
                                                `--+--Jingshanosaurus
                                               `--Anchisauria
                                                  |--Anchisaurus
                                                  `--+--Aardonyx
                                                     `--+*-Camelotia
                                                        |--Melanorosaurus
                                                        `--Sauropoda
                                                           |--Blikanasaurus
                                                           `--+--+--Antetonitrus
                                                              | `--Lessemsaurus
                                                              `--+--Gongxianosaurus
                                                                 `--Gravisauria
                                                                    |--Tazoudasaurus
                                                                    `--+--Vulcanodon
                                                                       `--+--Isanosaurus
                                                                          `--Eusauropoda
                                                                             |--+--Barapasaurus
                                                                             | `--Patagosaurus
                                                                             `--+--Shunosaurus
                                                                                `--+--+--Omeisaurus
                                                                                   | `--Mamenchisaurus
                                                                                     `--+--Cetiosaurus
                                                                                        `--Neosauropoda

Camelotia is outside Gongxianosaurus+Gravisauria.

Unlike Ezcurra's matrix, guaibasaurids aren't necessarily monophyletic (and note pruning Agnosphitys or Panphagia does not make them monophyletic), but are all sauropodomorphs unlike Yates' original. Also like Ezcurra but unlike Yates, Eoraptor is sister to Avepoda.

In Ignavusaurus' description, it was basal to Efraasia, but here it's more derived. Unlike Yates et al. (2010) but like Yates (2004), Gryponyx is a massospondylid, and unlike Sertich and Loewen (2010) the Lufengosaurus clade are also massospondylids. Yunnanosaurus is now basal to Jingshanosaurus.

"Dachongosaurus" - Zhao's nomina nuda part 2

2011-01-06T01:27:00.000-08:00

The first entries in this series are sauropodomorphs, so repeat some information from the first post of the year (including photos for completeness sake). Remember general references are given in part 1.

Specimen of "Dachongosaurus yunnanensis" (after Zhao, 1985).

"Dachongosaurus yunnanensis" Zhao, 1985
"Dachungosaurus yunnanensis" Zhao, 1985
Etymology- Dachong refers to the red color of the beds it was found in, while the species name refers to the province it was discovered in.
Sinemurian, Early Jurassic
Shawan Member of the Lufeng Formation, Dafongtian, Yunnan, China
Material- (~9.7 m) partial skeleton including at least nine dorsal vertebrae (~118 mm), seventeen dorsal ribs, femur (~955 mm)
Comments- "Dachongosaurus" is used in the text, while "Dachungosaurus" is used in the plate caption. Which will be used (if either) if it is eventually officially named is unknown.
A photo of the skeleton in situ is in Zhao (1985). Li et al. (1998) include Dachongosaurus yunnanensis in a faunal list. The length is estimated based on comparison with Jingshanosaurus, using the femoral length estimated from the photo.
Relationships- Stated by Zhao (1985) to be a basal sauropod with some derived features. Lambert (1990) listed it as a cetiosaurid, which Olshevsky (1991) also referred it to provisionally. Glut (1997) merely listed it as Sauropodomorpha incertae sedis. While few details are available from the photo, the femur appears to be strongly sigmoidal unlike the condition in sauropods. While the size is large for a non-sauropod, it is approached by some taxa such as Jingshanosaurus (femur 880 mm). It may in fact be a Jingshanosaurus specimen, though the material itself has not yet been described (contra the possibility alluded to on Wikipedia), as the Jingshanosaurus holotype is positioned differently and Xixiposaurus is much smaller. For now I recommend placing it as Plateosauria incertae sedis, as the large size is at least unknown in more basal sauropodomorphs.
Reference- Li, Zhang and Cai, 1998. The Characteristics of the Composition of the Trace Elements in Jurassic Dinosaur Bones and Red Beds in Sichuan Basin. Geological Publishing House, Beijing. 155 pp.

Zhao's nomina nuda Part 1: changduensis

2011-01-05T13:16:00.000-08:00

Since I've now acquired Zhao's 1985 paper (graciously translated by Leo Sham), the next several posts will be different than usual in that they won't involve theropods. Ever since I read Lambert's (1990) Dinosaur Data Book (the inspiration for my website's title, btw), I've been intrigued by the obscure dinosaurs named by Zhao- "Damalasaurus", "Tianchungosaurus", "Ngexisaurus", etc.. What were these? As I learned more about dinosaurs, I found out even most professionals didn't know. Over the past week I've poured over all of the available information on these taxa to present the most detailed treatment they've ever received. Some material from my last post will be repeated, but I've also uncovered earlier uses for some genera than even Olshevsky's lists show, and have a few new ideas of my own. The theropods are on my website already (with some minor updates forthcoming), but since it doesn't include sauropodomorphs or ornithischians, I've decided to place the non-theropod summaries on this blog. There are several references relevant to most taxa, and these are given below and not repeated in every entry. The first taxon is one of the most obscure, largely because Zhao didn't create a new genus for it...

Lufengosaurus "changduensis" Zhao, 1985
Etymology- Changdu is an alternative spelling of Qamdo, the county it was discovered in.
Early Jurassic
Middle Daye Group, Qamdo County, Daye, Tibet, China
Comments- This species is apparently illustrated by Yang (1986). Weishampel et al. (2004) include it in their faunal list along with an undescribed prosauropod which may be the same thing.
Relationships- Listed as a plateosaurid by Chure and McIntosh (1989) and Fang et al. (2006), and as an undescribed anchisaurid by Weishampel (1990). Lufengosaurus has more recently been placed as a basal massopod, but being undescribed, there is no published evidence "changduensis" belongs in Lufengosaurus or is distinct from L. huenei.
Reference- Yang, 1986. The Jurassic System. in Yang, Cheng and Wang (eds.). The Geology of China. Clarendon Press. 140-152.

General References- Zhao, "1983" [unpublished]. The Mesozoic vertebrate remains of Xizang (Tibet), China. The Series of the Scientific Expeditions to the Qinghai-Xizang Plateau. Palaeontology of Xizang. 2, 1-200.

Zhao, 1983. Phylogeny and evolutionary stages of Dinosauria. Acta Palaeontologica Polonica. 28(1-2), 295-306.

Zhao, 1985. The Jurassic Reptilia. In Wang, Cheng and Wang (eds.). The Jurassic System of China. Stratigraphy of China. 11, 286-289, 347, plates 10 and 11.

Zhao and Cheng, 1985. The Qamdo-Simao Subregion. In Wang, Cheng and Wang (eds.). The Jurassic System of China. Stratigraphy of China. 11, 174-179.

Chure and McIntosh, 1989. A Bibliography of the Dinosauria (Exclusive of the Aves) 1677-1986. Museum of Western Colorado Paleontology Series #1. 226 pp.

Lambert, 1990. The Dinosaur Data Book. New York: Avon Books. 320 pp.

Weishampel, 1990. Dinosaurian distribution. in Weishampel, Dodson and Osmolska (eds.). The Dinosauria. University of California Press. 63-139.

Olshevsky, 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.

Glut, 1997. Dinosaurs - The Encyclopedia. McFarland Press, Jefferson, NC. 1076 pp.

Zhang and Li, 1997. Mesozoic Dinosaur Localities in China and Their Stratigraphy. In Wolberg, Sump and Rosenberg (eds.). Dinofest International, Proceedings of a Symposium sponsered by Arizona State University. A Publication of The Academy of Natural Sciences. 265-273.

Olshevsky, DML 1999. http://dml.cmnh.org/1999Nov/msg00507.html

Weishampel, Barrett, Coria, Le Loeuff, Xu, Zhao, Sahni, Gomani and Noto, 2004. Dinosaur Distribution. in Weishampel, Dodson and Osmolska (eds.). The Dinosauria: Second Edition. University of California Press. 517-606.

Fang, Zhang, Lu, Han, Zhao and Li, 2006. Collision between the Indian Plate and the paleo-Asian late and the appearance of Asian dinosaurs. Geological Bulletin of China. 25(7), 862-873.