Benson's data integrated- Neovenatoridae tested

One of the best new theropod workers out there is Roger Benson.  He's been redescribing tons of megalosaurs (e.g. Megalosaurus, Duriavenator, Magnosaurus) and his cladistic analyses are of high quality.  As his non-coelurosaur tetanurine analysis incorporates several controversial taxa (e.g. Marshosaurus, Monolophosaurus, Chuanodongocoelurus, Lourinhanosaurus, Shaochilong, Chilantaisaurus, Megaraptor, Fukuiraptor, Aerosteon) and resulted in novel clades (e.g. Neovenatoridae, Megaraptora), I've been interested to see what adding his data to my saurischian supermatrix would do.  As a reminder, the saurischian supermatrix takes all the taxa, characters and codings from most of the relevent studies of non-coelurosaur theropods.  These include Smith et al. (2007, 2008), Tykoski (2005), Carrano and Sampson (2007), Ezcurra and Novas (2006), Rauhut (2003), Allain (2002), Azuma and Currie (2000), Brusatte and Sereno (2008), Sereno and Brusatte (2008), and now Benson (2010) and Benson et al. (2010).  It also has all the data from Langer and Benton (2006) and Yates (2006) to help outgroup comparisons with sauropodomorphs and basal avematatarsalians.  Not all included taxa are coded for all characters yet, which is a flaw I noted in several recent analyses (but note I wouldn't publish mine as is), and codings are basically all taken from their matrices and assumed to be correct.  The exception to the latter is when codings disagree, so I check them against the literature, and the 37 non-coelurosaur tetanurines which I've gone through the entire matrix with.  All together it has 159 taxa and 925 characters.  Here's Benson et al.'s (2010) cladogram-

|--"Megapnosaurus" kayentakatae
|--Dilophosaurus
`--+--+--Ceratosaurus
   |  `--Abelisauridae
   `--Tetanurae
      |*-Chuandongocoelurus
      |--Megalosauroidea
      |  |--+--Xuanhanosaurus
      |  |  `--+--Marshosaurus
      |  |     `--+--Piatnitzkysaurus
      |  |        `--Condorraptor
      |  `--+--Monolophosaurus
      |     `--Spinosauroidea
      |        |*-Piveteausaurus
      |        |--Spinosauridae
      |        |  |--+--Baryonyx
      |        |  |  `--Suchomimus
      |        |  `--+--Irritator
      |        |     `--Spinosaurus
      |        `--Megalosauridae
      |           |--Eustreptospondylinae
      |           |  |--Eustreptospondylus
      |           |  `--+--Streptospondylus
      |           |     `--Magnosaurus
      |           `--Megalosaurinae
      |              |--Duriavenator
      |              `--+--+--Afrovenator
      |                 |  `--Dubreuillosaurus
      |                 `--+--Torvosaurus
      |                    `--Megalosaurus
      `--Avetheropoda
         |--Carnosauria
         |  |--Sinraptoridae
         |  |  |--+--Lourinhanosaurus
         |  |  |  `--Poekilopleuron
         |  |  `--+--Sinraptor
         |  |     `--Metriacanthosaurus
         |  `--+--Allosaurus
         |     `--Carcharodontosauridae
         |        |--+--Eocarcharia
         |        |  `--+--Acrocanthosaurus
         |        |     `--+--Shaochilong
         |        |        `--+--Tyrannotitan
         |        |           `--Carcharodontosaurinae
         |        |              |--Carcharodontosaurus
         |        |              |--Giganotosaurus
         |        |              `--Mapusaurus
         |        `--Neovenatoridae
         |           |--Neovenator
         |           `--Megaraptora
         |              |*-Orkoraptor
         |              |--Chilantaisaurus
         |              `--+--+--Australovenator
         |                 |  `--Fukuiraptor
         |                 `--+--Aerosteon
         |                    `--Megaraptor
         `--Coelurosauria
            |--Compsognathus
            `--+--Tanycolagreus
               `--Guanlong

Within his trees, Chuandongocoelurus is excluded from Avetheropoda, Spinosauroidea and the Xuanhanosaurus+Piatnitzkysaurus clade.  Piveteausaurus is excluded from Spinosauridae.  And here's the results of my analysis once pruned (after running it) to include only those taxa present in Benson et al.'s matrix.

|--+--"Megapnosaurus" kayentakatae
|  `--Dilophosaurus
`--+--+--Ceratosaurus
   |  `--Abelisauridae (9 taxa)
   `--Tetanurae
      |--Chuandongocoelurus
      `--+--Xuanhanosaurus
         `--+--+--Marshosaurus
            |  `--+--Piatnitzkysaurus
            |     `--Condorraptor
            `--+--Megalosauroidea
               |  |--Poekilopleuron
               |  `--+--+--Piveteausaurus
               |     |  `--Spinosauroidea
               |     |     |--Torvosaurus
               |     |     `--Spinosauridae
               |     |        |--+--Baryonyx
               |     |        |  `--Suchomimus
               |     |        `--+--Irritator
               |     |           `--Spinosaurus
               |     `--Megalosauridae
               |        |--Afrovenator
               |        `--+--Megalosaurus
               |           `--Eustreptospondylinae
               |              |--Dubreuillosaurus
               |              `--+--Duriavenator
               |                 `--+--Eustreptospondylus
               |                    `--Magnosaurus
               `--+--Monolophosaurus
                  `--+--+--Streptospondylus
                     |  `--Lourinhanosaurus
                     `--Avetheropoda
                        |--Carnosauria
                        |  |--Sinraptoridae
                        |  |  |--Sinraptor
                        |  |  `--Metriacanthosaurus
                        |  `--+--Allosaurus
                        |     `--Carcharodontosauridae
                        |        |--Neovenator
                        |        `--+--Eocarcharia
                        |           `--+--Acrocanthosaurus
                        |              `--Carcharodontosaurinae
                        |                 |--Shaochilong
                        |                 |--Tyrannotitan
                        |                 |--Carcharodontosaurus
                        |                 |--Chilantaisaurus
                        |                 `--Giganotosaurini
                        |                    |--Giganotosaurus
                        |                    `--Mapusaurus
                        `--Coelurosauria
                           |--Megaraptora
                           |  |--Fukuiraptor
                           |  `--+-Orkoraptor
                           |     `--+--Australovenator
                           |        `--+--Aerosteon
                           |           `--Megaraptor
                           `--+--Guanlong
                              `--+--Compsognathus
                                 `--Tanycolagreus


Chuandongocoelurus was identified as an elaphrosaur by me back on the DML several years ago, and as a megalosauroid related to Monolophosaurus in Benson's original (2008, 2010) analysis.  Now Benson finds it to be a basal tetanurine of uncertain placement, while I place it as the basalmost tetanurine.  Why the difference?  The main one is that Benson only codes the holotype, which includes mostly hindlimb elements.  Most of the Elaphrosaurus-like characters are in the vertebrae, which belong to the paratype.  I coded both as separate OTUs and found the paratype to be sister to Elaphrosaurus.

Benson finds a clade consisting of Xuanhanosaurus, Piatnitzkysaurus, Condorraptor and Marshosaurus at the base of Megalosauroidea.  The first three have traditionally been placed outside Megalosauroidea + Avetheropoda, while Marshosaurus has been controversial.  My results are intermediate.  All of these taxa are outside Megalosauroidea + Avetheropoda, but the latter three do form a clade with the same topology found by Benson.  In my last post I wondered if Marshosaurus' position would be affected by including pelvic characters, and it seems the answer is no.  One important question is if the snout, pelvis and partial skeleton belong to the same taxon.  I may try running them as separate OTUs sometime.  It should be noted that in my analysis Kaijiangosaurus, "Szechuanoraptor" and "Sezchuanosaurus" zigongensis form a clade with Xuanhanosaurus, while Shidaisaurus is sister to Marshosaurus.  Erectopus is more basal than any of these, while Tugulusaurus is a tetanurine outside of Avetheropoda or Megalosauroidea.
 
Among the core megalosauroids, our topologies are different besides Spinosauridae, Megalosauridae (though mine excludes Torvosaurus) and placing Magnosaurus and Eustreptospondylus close.  There are a few taxa which have varied between megalosauroids and carnosaurs in analyses.  Monolophosaurus has traditionally been placed as a basal carnosaur, but Benson found it to be a megalosauroid.  My analysis agrees with Smith et al.'s in placing it sister to Avetheropoda.  Poekilopleuron is usually thought to be close to Megalosaurus, though Benson found it to be a sinraptorid carnosaur.  My analysis agrees with Allain and Chure (2002), who proposed it may be a basal megalosauroid.  Lourinhanosaurus has been found to be both a carnosaur (Mateus, 1998; Holtz et al., 2004; Benson et al., 2010) and a megalosauroid (Allain, 2002), but my analysis is intermediate in placing it sister to Avetheropoda.  Finally, Streptospondylus has been generally viewed as a eustreptospondyline (Allain, 2001; Smith et al. 2007; Benson et al., 2010), but in my analysis it is sister to Lourinhanosaurus instead.
 
In Carnosauria, everyone has been focusing on carcharodontosaurids to the exclusion of more basal taxa (e.g. Yangchanosaurus, Saurophaganax).  But my analysis does agree with the growing consensus that sinraptorids are basal to Allosaurus and carcharodontosaurids.  Both Benson and I found that Metriacanthosaurus is sister to Sinraptor, providing yet more evidence this clade should be called Metriacanthosauridae instead of Sinraptoridae.  Our topology within Carcharodontosauridae is basically identical, though mine is less resolved toward the tip due to Chilantaisaurus' presence.  Notably, Siamotyrannus was resolved in my analysis as a carnosaur more derived than sinraptorids, but less than Allosaurus.
 
The main point of Benson et al.'s (2010) paper was the discovery of a new clade of carnosaurs- Neovenatoridae.  This contained the basal carcharodontosaurid Neovenator, as well as the Megaraptora.  Megaraptora contains many taxa which have been seen as spinosaur relatives (Megaraptor, Chilantaisaurus), carnosaurs (Chilantaisaurus, Fukuiraptor, Australovenator, Aerosteon, Megaraptor) or coelurosaurs (Chilantaisaurus, Fukuiraptor, Orkoraptor, Megaraptor) in the literature.  The relationship between Australovenator and Fukuiraptor was noted in the former's description, while I noted the resemblence between Orkoraptor and Aerosteon (I viewed all four of these taxa as basal coelurosaurs).  But combining all these genera into a carcharodontosaur clade was unexpected.  My analysis agrees with Benson in the monophyly of Megaraptora (except Chilantaisaurus) and placing Megaraptor and Aerosteon as sister taxa within it.  However, it places Megaraptora in Coelurosauria, with Neovenator and Chilantaisaurus as carcharodontosaurids.  Within Coelurosauria, Megaraptora is outside Tyrannoraptora, but more derived than Gasosaurus.
 
Next time... the first of many Pickering taxa.

The Marshosaurus of Benson isn't Marshosaurus

I'm finishing up integrating Benson's (2010) and Benson et al.'s (2010) characters/codings in my saurischian supermatrix.  One thing I found that's great about Benson's matrix is that it codes the currently undescribed partial skeleton that's been referred to Marshosaurus (CMNH 21704).  It consists of a posterior skull, most of the presacrals, the scapula and a humerus, which were originally reported by Chure et al. in 1993 and later referred tentatively to Marshosaurus by Chure et al. (1997).  Its referral is only tentative since no elements overlap with the type material, which consists of pelvic and snout elements.   Benson finds Marshosaurus to be related to taxa which he recovers as megalosauroids (Piatnitzkysaurus, Condorraptor, Xuanhanosaurus), but which are placed even more basally in most phylogenies.  I found that when I coded Marshosaurus for my supermatrix, it ended up as a sinraptorid (only including a few characters from CMNH 21704).  So why the difference?  Well, it seems Benson didn't code basically any pelvic characters for Marshosaurus (except a lack of pelvic fusion, and pubic peduncle size).  Now maybe he thinks the pelvis belongs to a different taxon than the cranial, axial and forelimb elements, since there's no overlap.  But there's a slight problem with this.  The holotype of Marshosaurus is an ilium!  The other pelvic elements fit it perfectly and some are even thought to come from the same individual.  So Benson's Marshosaurus OTU excludes the only material we know for sure is Marshosaurus.  Would the pelvic elements influence its position?  We'll have to see what happens once all that data is in my supermatrix.

Benson, 2010. A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society. DOI 10.1111/j.1096-3642.2009.00569.x

Benson, Brusatte and Carrano, 2010. A new clade of large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic. Naturwissenschaften. 97, 71-78.

Chure, Britt and Madsen, 1997. A new specimen of Marshosaurus bicentesimus (Theropoda) from the Morrison Formation (Late Jurassic) of Dinosaur National Monument. Journal of Vertebrate Paleontology. 17(3) 38A.

Chure, Madsen and Britt, 1993. New data on theropod dinosaurs from the Late Jurassic Morrison FM. (MF). Journal of Vertebrate Paleontology. 13(3) 30A.

Rahiolisaurus, a new Lameta abelisaurid

Remember that incomplete abelisaurid skeleton Chatterjee and Rudra (1996) illustrated?  It's finally getting described and named.  Thanks to a bibliographic entry in Mendez et al. (2010), we know its name- Rahiolisaurus gujaratensis.  According to Chatterjee and Rudra's skeletal reconstruction, the arms were quite plesiomorphic, but we'll see what the actual bones say in June.

Chatterjee and Rudra, 1996. KT events in India: impact, rifting, volcanism and dinosaur extinction. Memoirs of the Queensland Museum. 39(3), 489-532.
 
Mendez, Novas and Chatterjee, 2010.  An abelisaurid humerus from the Upper Cretaceous of India. Palaontol Z. DOI 10.1007/s12542-010-0055-z
 
Novas, Chaterjee, Rudra and Datta, 2010. Rahiolisaurus gujaratensis, n. gen. n. sp., a new abelisaurid theropod from the Late Cretaceous of India. In Bandyopadhyay (ed). New Aspects of Mesozoic Biodiversity. 132. Heidelberg: Springer. Lecture Notes in Earth Science.

Article 13.1.1 means Lewisuchinae/idae is doomed and that Unenlagiinae and Microraptorinae are misattributed

First, an apology to the authors of the Asilisaurus paper for implying in my previous post that a reason the named Silesauridae as a clade instead of a family was to avoid priority issues with Lewisuchinae/idae.  As pointed out on the Chinleana blog, ICZN Article 13.1.1 states a new family-level name requires a definition or diagnosis, which Paul does not provide for Lewisuchinae.  Thus it is a nomen nudum, and Silesauridae is the first validly proposed family-level name for the group.

This made me wonder how many other family-level non-neornithine theropod taxa are nomina nuda.  Specifically, Article 13 states family-level taxa named after 1930 need "a description or definition that states in words characters that are purported to differentiate the taxon" or a bibliographic reference to such a statement (note I think a phylogenetic definition counts as a definition).  They can also "be proposed expressly as a new replacement name (nomen novum) for an available name, whether required by any provision of the Code or not."  However, Article 13.2.1 states "A family-group name first published after 1930 and before 1961 which does not satisfy the provisions of Article 13.1 is available from its original publication only if it was used as valid before 2000, and also was not rejected by an author who, after 1960 and before 2000, expressly applied Article 13 of the then current editions of the Code."  Also, Article 13.5 states that if a family-level name and nominal genus are proposed in the same work, one definition/diagnosis will do.  Before 1931, the rules are less strict, and any family named from a valid genus was considered valid (Article 12.2.4).  The groups are listed as families below for simplicity, though some have only been explicitly proposed as subfamilies.

Valid due to definition/diagnoses- Herrerasauridae, Staurikosauridae, Guaibasauridae, Protoavidae, Dilophosauridae sensu Madsen and Welles 2000, Noasauridae, Velocisauridae, Abelisauridae, Carnotauridae, Streptospondylidae, Eustreptospondylidae, Torvosauridae, Baryonychidae, Irritatoridae, Sigilmassasauridae, Sinraptoridae, Metriacanthosauridae, Neovenatoridae, Giganotosauridae, Iliosuchidae, Shanshanosauridae, Albertosauridae, Sinosauropterygidae, Ornitholestidae, Bradycnemidae, Praeornithidae, Deinocheiridae, Harpymimidae, Garudimimidae, Alvarezsauridae, Parvicursoridae, Mononykidae, Alxasauridae, Therizinosauridae, Segnosauridae, Nanshiungosauridae, Caudipteridae and therefore Caudipteryidae, Elmisauridae, Avimimidae, Kuszholiidae, Ingeniidae, Saurornithoididae, Archaeornithoididae, Itemiridae, Unenlagiidae sensu Makovicky et al. 2005, Microraptoridae sensu Longrich and Currie 2009, Saurornitholestiidae, Velociraptoridae, Scansoriopterygidae, Jeholornithidae, Yandangithidae and therefore Yandangornithidae, Omnivoropterygidae, Sapeornithidae, Confuciusornithidae, Aberratiodontuidae, Cuspirostrisornithidae, Iberomesornithidae, Protopterygidae, Alexornithidae, Enantiornithidae sensu Nessov 1984, Longipterygidae, Longirostravisidae, Alethoalaornithidae, Avisauridae, Boluochidae, Concornithidae, Eoenantiornithidae, Gobipterygidae, Cathayornithidae, Liaoningornithidae, Hongshanornithidae, Patagopterygidae, Songlingornithidae, Yanornithidae, Yixianornithidae, Eurolimnornithidae, Limnornithidae Kessler and Jurcsak 1984, Zhyraornithidae, Gansuidae, Plegadornithidae, Angelinornithidae, Asiahesperornithidae, Ambiortidae.

Valid due to being named between 1931 and 1960 and used as valid before 2000- Halticosauridae, Segisauridae, Bahariasauridae, Erectopodidae, Carcharodontosauridae, Antrodemidae, Caenagnathidae, Elopterygidae.

Valid due to being named before 1931- Coelophysidae, Podokesauridae, Procompsognathidae, Ceratosauridae, Megalosauridae, Spinosauridae, Allosauridae, Labrosauridae, Dryptosauridae, Tyrannosauridae, Aublysodontidae, Deinodontidae, Coeluridae, Compsognathidae, Ornithomimidae, Oviraptoridae, Troodontidae, Dromaeosauridae, Ornithodesmidae, Archaeopterygidae, Archaeornithidae, Ichthyornithidae, Enaliornithidae, Baptornithidae, Hesperornithidae.

Invalid- Dilophosauridae Charig and Milner 1990, Acrocanthosauridae, Unquillosauridae (in a thesis), Erlikosauridae, Rahonavidae, Unenlagidae Bonaparte 1999, Microraptorinae Makovicky et al. 2005, Enantiornithidae Nessov and Borkin 1983, Sinornithidae, Chaoyangidae, Chaoyangornithidae, Limnornithidae Kessler 1984, Palaeocursornithidae, Apsaravidae.

The only ones which are commonly used today are Unenlagidae (as Unenlagiinae) and Microraptoridae (as Microraptorinae), but these should be attributed to Makovicky et al. (2005) and Longrich and Currie (2009) respectively.

Unknown, as I lack the papers- Syntarsiidae (Kalandadze and Rautian, 1991), Torvosauridae (Galton, 1985), Struthiomimidae (Ostrom, 1972), Enantiornithidae (Nessov and Borkin, 1983), Liaoxiornithidae (Hou et al., 2002), Palaeocursornithidae (Jurcsak and Kessler, 1988).
Note Torvosauridae is at least valid under Kurzanov (1989), Struthiomimidae under Kaiser (2007), and Enantiornithidae under Nessov (1984) though.  If anyone wants to send the references to me (at Mickey_Mortimer111@msn.com), I'd be grateful.

UPDATE

Thanks to Jerry Harris for providing a few of the references.  Torvosauridae is valid due to a diagnosis.  Palaeocursornithidae is invalid since it's just a name in a taxonomic list.  Enantiornithidae is also invalid for Nessov and Borkin 1983, since they merely refer to PO 3494 (a proximal tarsometatarsus) as being a member of that family, without comment.

Hou, Zhou, Zhang and Gu, 2002. Mesozoic birds from western Liaoning in China. ISBN 7-5381-3392-5. 120 pp.

Jensen, 1985. Uncompahgre dinosaur fauna: A preliminary report. Great Basin Naturalist. 45, 710-720.

Jurcsak and Kessler, 1988. Evolutia avifaunei pe teritoriul Romaneie. III . Filogenie si sistematica. Cistia. 18, 647-688.

Kalandadze and Rautian, 1991. Late Triassic zoogeography and reconstruction of the terrestrial tetrapod fauna of North Africa. Paleont. Journ. 1, 1-12.

Nessov and Borkin, 1983. New records of bird bones from Cretaceous of Mongolia and Middle Asia. Trudy Zoologicheskogo Instituta AN SSSR. 116, 108-110.

Ostrom, 1972. Dinosaur. in McGraw-Hill Yearbook, Science and Technology. 176-179.

Asilisaurus and how not to name new clades

The good news is that we have a new taxon of basal dinosauriform.  The bad news is the clade the authors placed their new genus is.  Based on their phylogenetic analysis, Nesbitt et al. found it to be in the same group as Silesaurus and Lewisuchus, exclusive of Dinosauria.  The idea of this clade has been floating around for a while, and was actually named by Langer et al. (2010) earlier this year.  Which authorship and definition have priority is not the subject of this post however, and in any case Nesbitt et al. are innocent as far as that goes since their paper was in review when Langer et al.'s came out.  What I care about here is that Nesbitt et al. named their clade Silesauridae, yet Paul named Lewisuchinae (and thus also Lewisuchidae, as the ICZN states all family-level taxa are named once one is) back in 1988.  I could just urge everyone to please Google any family-level version of your new clade's genera before you give it a new name.  Basically all proposed archosaur nomenclature is online, so this will stop you from creating another junior synonym.

Yet the solution isn't that easy, because Silesauridae sensu Nesbitt et al. is an example of an increasingly common trend to name taxa as "clades, not Linnaean ranks."  Thus the authors claim the ICZN's rules of priority don't apply, since Silesauridae isn't really a family.  Now I'm a huge fan of phylogenetic nomenclature, but to that I'm afraid I must reply "Bullshit."  I think most dinosaur paleontologists agree nowdays that Linnaean ranks have no objective meaning.  One family is not necessarily more similar to another family than to another order, they're just all labels for taxa.  The only way to tell that a particular group is a family is that it ends in -idae.  I'd also say most dinosaur paleontologists only recognize monophyletic taxa (clades) in their taxonomy.  So basically whenever we talk about dinosaur families, we are talking about clades whose names end in -idae.  So why would anyone name a clade with an -idae suffix and not intend it as a family?!  Just to avoid priority?  I always thought it was a respectful (and interesting) task to go through historically proposed taxonomy and credit the first author who proposed a name for a group.  To do otherwise is too similar to Sereno's habit of finding new more complete remains probably belonging to poorly known but named taxa, giving his specimen a new name, and calling the already existing taxon a nomen dubium.   Just rewriting taxonomy with our own labels as we go along.  Or do the authors do this as a rebellious example of the fact no one has to follow the ICZN?  That it has no real power over us and is an archaic system whose subjective rules shouldn't be obeyed lest we fall into the unscientific idea of tradition?  I hate to have to play the part of a conservative, but the truth is we have no other code at the moment.  I'll jump on board Phylocode once it's enacted, and think it's great to start following Phylocode rules beforehand but that doesn't mean we have to disobey the ICZN.  Since Phylocode won't be retroactive anyway, nothing we publish now will count towards it, and following only its rules means you're not really following any rules at all.  You're just following a game of pretend that leaves us who actually try to follow the rules asking how we're supposed to treat your actions.  We could ignore what you say and treat Silesauridae as a family, and thus a junior synonym of Lewisuchidae (which will probably be my strategy).  We could treat Lewisuchidae as a family and Silesauridae as an unranked taxon, the first only including Lewisuchus itself (which results in making Lewisuchidae redundant and gives the impression of nested families).  We could redefine Silesauridae to be the sister taxon of Lewisuchidae (which would create a third definition for Silesauridae, and all before any of them are official).  We could petition the ICZN to sink Lewisuchidae (not likely to happen).  It just makes things so complicated, yet some of it could have been solved if you just used a non-family group suffix and named it Silesauria instead, if you were insistant on basing the clade on Silesaurus.  Senter et al. (2004) provided a great example when naming Microraptoria instead of Microraptoridae/inae.

In conclusion, I ask everyone to please-
- Google any family-level version of your new clade's genera before you give it a new name.
- Follow the ICZN's rules at least until Phylocode is enacted.
- Don't use a Linnaean rank suffix if your intent is to name a rankless taxon that doesn't compete for priority in the ICZN.

Langer, Ezcurra, Bittencourt and Novas. 2010. The origin and early evolution of dinosaurs. Biological Reviews of the Cambridge Philosophical Society. 85, 55–110.

Nesbitt, Sidor, Irmis, Angielczyk, Smith and Tsuji, 2010. Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira. Nature. doi:10.1038/nature08718

Senter, Barsbold, Britt and Burnham, 2004. Systematics and evolution of Dromaeosauridae. Bulletin of Gunma Museum of Natural History. 8, 1-20.

Picture of the Day- Ornitholestes

Ah, Ornitholestes.  Such a well known dinosaur, but with so many mysteries and misconceptions.  Of course, everyone knows by now that the supposed horn above the naris identified by Paul (1988) is really taphonomic. 

Snout in left lateral view (copyright AMNH).  Note the many ways I failed SVPOW photo taking guidelines. ;)

Everyone also knows the manus (AMNH 587) referred to it has been reassigned to Tanycolagreus.  You might also realize that Carpenter et al. (2005) incorrectly state only one humerus is known, do not mention the ulnar or left radial fragments, incorrectly list metacarpal II or III as being preserved, as well as fragments of two other metacarpals, and only mention one of the two manual unguals.  Senter (2006) did a nice job of describing this forelimb material. 

Humeri in anterior view, five radial and ulnar fragments, metacarpal I, phalanges and two manual unguals.

For a while (Gilmore, 1920 to Ostrom, 1980) Ornitholestes was thought to be synonymous with Coelurus, and even after this mistake was realized it was not uncommon to find illustrations of Coelurus' skull or head obviously based on Ornitholestes.  In reality, Coelurus' skull is only known from a partial dentary.  Less well known is that even though Paul described the taxon as having unusually short lower legs, the tibiae are not preserved and only the proximal fibula is known (though not mentioned by Carpenter et al.). 

Incomplete fibla and femur in medial view.

Another fun fact about Ornitholestes is that it had an enlarged ungual on pedal digit II.  It seems like a big deal than a non-paravian would have one, but barely anyone mentions it.  You can even see a raised distal articular surface on pedal phalanx II-1 (as was recently described in Archaeopteryx) suggesting hyperextensibility. 

Metatarsus, pedal phalanges and pedal unguals in medial view.  Note base of large pedal ungual II and dorsally projecting distal articulation on II-1 at top.

Finally, we have its phylogenetic position.  It's been seen as everything from a carnosaur (Paul, 1988) to a deinonychosaur (Makovicky, 1995), with most authors finding something intermediate.  The cast pictures are courtesy of Phil Senter, the snout pic is one I took.


Gilmore, 1920. Osteology of the carnivorous Dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus. Bull. U. S. Nat. Mus. CX 1-154, 36 pls., 78 text-figs.

Ostrom, 1980. Coelurus and Ornitholestes: are they the same? In Jacobs, L. (ed.) Aspects of Vertebrate History. Flagstaff, Museum of Northern Arizona Press. 245-256.

Paul, 1988. The small predatory dinosaurs of the mid-Mesozoic: the horned theropods of the Morrison and Great Oolite - Ornitholestes and Proceratosaurus - and the sickleclaw theropods of the Cloverly, Djadokhta, and Judith River - Deinonychus, Velociraptor, and Saurornitholestes. Hunteria. 2(4), 1-9.

Makovicky, 1995. Phylogenetic aspects of the vertebral morphology of Coelurosauria (Dinosauria: Theropoda). M.S. thesis, Univ. Copenhagen, 311pp.

Carpenter, Miles, Ostrom and Cloward, 2005. Redescriptions of the small maniraptoran theropods Ornitholestes and Coelurus from the Upper Jurassic Morrison Formation of Wyoming. In Carpenter (ed.). The carnivorous dinosaurs. Indiana University Press. pp. 49-71.

Senter, 2006. Forelimb function in Ornitholestes hermanni Osborn (Dinosauria, Theropoda). Palaeontology. 49(5), 1029-1034.