Zhao 1986 Cretaceous dinosaurian nomina nuda first impressions

Thanks to Molnar for sending me Zhao's rare 1986 paper on Chinese Reptilia.  In fact, it's so rare that many references confuse it with his 1985 Jurassic reptile paper from another volume in the series and I've only seen its title listed once (by Olshevsky, 1991).  The full citation is...

Zhao, 1986. The Cretaceous biota of China: Reptilia. in Hao, Su, Yu, Li, Li, Wang, Qi, Guan, Hu, Liu, Yang, Ye, Shou, Zhang, et al.. The Cretaceous System of China. Stratigraphy of China. 12, 67-73, plates XI, XII.

As with Zhao 1985 (download the pdf I made of the translation here), I'm working on having someone who actually knows Chinese translate it for me.  In the meantime, I've used OCR software and Google Translate to try my hand at translating the information about the dinosaurian nomina nuda.  Unfortunately, there's not as much information given about each species here as there was in the 1985 paper.  But here's what we have...

Microvenator? "chagyabi" is mentioned once in the Early Cretaceous coelurosaur section, said to be from Tibet.  So nothing new there.

"Megacervixosaurus tibetensis" is also mentioned once, in the Late Cretaceous sauropod section.  Also said to be from Tibet, so again nothing new.

Tyrannosaurus "lanpingi" actually gets the best treatment, since it's the one dinosaur nomen nudum photographed in the paper.  Note Ye (1975) originally named it "lanpingensis", though Zhao credits "lanpingi" to himself (as Chao; though his name is spelled Zhao for the article itself).  The photo is the basal half of a tooth crown in labial view, and has a FABL of ~32 mm.  Only distal serrations are evident, which are small (8 per 5 mm) and have apically angled blood grooves.  The size and serration density fall within the range of Tyrannosaurus rex, but also Carcharodontosaurus saharicus.  Angled blood grooves are known for tyrannosaurids and Carcharodontosaurus, but also taxa like Fukuiraptor.  Importantly, there seem to be prominent enamel wrinkles along the distal carina.  These are almost never found in tyrannosauroids, but are known in derived carcharodontosaurids, Allosaurus and Fukuiraptor (Brusatte et al., 2007).  As "lanpingensis" is from the Early Cretaceous Jingxing Formation of Yunnan, it's more likely to be a megaraptoran or carcharodontosaurid than an allosaurid or tyrannosaurine.  Both are clades known from large taxa (Chilantaisaurus; Carcharodontosaurus, Giganotosaurus, Mapusaurus) and both are known from Asia (Chilantaisaurus, Fukuiraptor; Shaochilong).  If we knew the basal width, we could tell more, since derived carcharodontosaurids have narrower teeth than Fukuiraptor (Molnar et al., 2009).  Maybe Ye (1975) will tell us, which I should be getting soon as well.  Until then, I recommend placing "lanpingensis" in Avetheropoda indet. if you follow my coelurosaurian megaraptorans, or Carnosauria indet. if you follow Benson.

Basal tooth crown of "Tyrannosaurus" "lanpingensis" (after Zhao, 1986).

Prodeinodon is mentioned with early Cretaceous carnosaurs, but not P? "tibetensis", which I was expecting.  "Monkonosaurus lawulacus" is mentioned in the Early Cretaceous ankylosaur/scolosaur section, but it's been subsequently described by Dong and Maidment, so isn't very interesting.  When I have an official translation, I'll correct any data mistranslated here, and add any further details.


In a completely unrelated note, I found an otherwise unmentioned Mesozoic bird name in O'Connor et al. (2011)- "Dalianornis mengi".  It's used in quotes in their data matrix, and is near certainly an early name for Shenquiornis mengi which was described by O'Connor in her thesis, then officially published by Wang et al. (2010).  Notably, Shenquiornis is used in the cladogram and main article.

References- Ye, 1975. Jurassic system. In Su (ed.). Mesozoic Redbeds of Yunnan. Academia Sinica, Beijing. 11-30.

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.

Olshevsky, 1991. A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.

Brusatte, Benson, Carr, Williamson and Sereno, 2007. The systematic utility of theropod enamel wrinkles. Journal of Vertebrate Paleontology. 27(4), 1052-1056.

Molnar, Obata, Tanimoto and Matsukawa, 2009. A tooth of Fukuiraptor aff. F. kitadaniensis from the Lower Cretaceous Sebayashi Formation, Sanchu Cretaceous, Japan. Bulletin of Tokyo Gakugei University, Division of Natural Sciences. 61, 105-117.

Wang, O'Connor, Zhao, Chiappe, Gao and Cheng, 2010. New species of Enantiornithes (Aves: Ornithothoraces) from the Qiaotau Formation in Northern Hebei, China. Acta Geologica Sinica. 84(2), 247-256.

O'Connor, Chiappe and Bell, 2011. Pre-modern birds: Avian divergences in the Mesozoic. in Dyke and Kaiser (eds.). Living Dinosaurs: The Evolutionary History of Modern Birds. 39-114.

Zhao 1986 coming soon

It's been quiet here lately as I finish the coelurosaur phylogeny.  But those of you who are fans of Microvenator? "chagyabi", "Tyrannosaurus" lanpingensis, Prodeinodon? "tibetensis" and "Megacervixosaurus tibetensis" will have cause to rejoice, since I'll soon have Zhao 1986 in my hands.

Zhao, 1986. The Cretaceous biota of China: Reptilia. in Hao, Su, Yu, Li, Li, Wang, Qi, Guan, Hu, Liu, Yang, Ye, Shou and Zang (eds.). The Cretaceous System of China. Stratigraphy of China. 12, 67-73, plates XI, XII.

New theropod Vitakrisaurus and Vitakridrinda's publication date settled

I've been trying to track down the publication officially describing Vitakridrinda, and have finally succeeded.

Malkani first mentioned this taxon in his 2003 description of Brohisaurus, referencing it as an abelisaurid described in "Malkani, 2004a". The only publication in the bibliography solely by Malkani is his saurischian biodiversity paper, listed as in process, but not actually published until 2006. As the 2003 mention of Vitakridrinda lacks a description or definition (ICZN Article 13.1.1; note the reference to Malkani, 2004a doesn't count under 13.1.2 since it was not published yet), was not indicated to be a new taxon (16.1), and did not have a type specimen indicated (16.4), it was a nomen nudum at the time. The first description of Vitakridrinda is generally claimed to be the 2004 "Saurischian Dinosaurs from Late Cretaceous of Pakistan", as referenced in Malkani 2006a and the Paleobiology Database. Yet ICZN Article 9.9 lists "abstracts of articles, papers, posters, texts of lectures, and similar material when issued primarily to participants at meetings, symposia, colloquia or congresses" as not being published work, so the paper doesn't count. In addition, it still violates 16.4 in not indicating a type specimen. Note while Malkani's "Saurischian dinosaurs from the Late Cretaceous Pab Formation of Pakistan" has been listed as being published in 2005 (Malkani, 2006a) or "2004d" and in review (Malkani, 2006b), Malkani confirms (pers. comm. 2012) that it remains unpublished. Two 2006 publications of Malkani's do describe Vitakridrinda sufficiently, with 2006b being published in December, while 2006a was published in April. Thus Malkani's 2006a publication is the actual official description of Vitakridrinda.

Perhaps more interesting is that while researching this, I found a theropod taxon which has gone unnoticed by the scientific community- Vitakrisaurus saraiki.  As usual for Malkani, he also erects Vitakrisaurinae, Vitakrisauridae and Vitakrisauria, because Pakistani dinosaurs can't possibly use the same classification as other dinosaurs do :| .  Note he had previously used Vitakrisauridae and Vitakrisaurinae in 2010 (New Pakisaurus (Pakisauridae, Titanosauria, Sauropoda) remains, and Cretaceous Tertiary (K-T) boundary from Pakistan. Sindh University Research Journal (Science Series). 42(1), 39-64) for Vitakridrinda and Rajasaurus, and Vitakririnda respectively.  Yet these were invalid then because Vitakrisaurus had yet to be named.  Incidentally he also tried naming Rajasaurinae within Vitakrisauridae in that publication, but that is also a nomen nudum as it was not given a diagnosis (ICZN Article 13.1.1) or explicitly stated to be new (ICZN 16.1).  It's really not clear if he thinks of Vitakrisauridae and Vitakrisauria as being the right names for Abelisauridae and Abelisauria (which would be absurd, but that seems to be his view of his titanosaur families Pakisauridae and Balochisauridae relative to Titanosauridae and Saltasauridae), or if he thinks they exist alongside them.

Incidentally, Malkani parallels the situation with his new baurusuchid Sulaimanisuchus kinwai.  Initially identified as a Pabwehshi specimen (and maybe what Malkani discusses in his 2004 abstract "First diagnostic fossils of Late Cretaceous crocodyliform (Mesueucrocoreptilia) from Pakistan"), he used the family Sulaimanisuchidae invalidly in the same 2010 paper as above before properly naming the genus, subfamily and family in 2010b.  Supposedly Pabwehshi and Sulaimanisuchus both belong to Sulaimanisuchinae, and Sulaimanisuchidae sounds like another attempt to improperly replace Baurusuchidae.  In any case, it's based on the anterior dentaries MSM-63-4, from the Maastrichtian Vitakri Formation.  I'm not qualified to reflect on its validity.

Vitakrisaurus saraiki holotype MSM-303-2 after Malkani 2010b.  My interpretation is that the elements on the top of the left photo are (left to right) pedal ungual II, phalanx II-2, phalanx II-1 and metatarsal II in medial view.  The latter three are also shown in dorsal view on the bottom edge of the specimen in the right photo.  A rather unrecognizable digit III seems to be above digit II in the right photo.  Above that, and below the end of digit II at left, are single phalanges which may belong to digit IV.

Vitakrisaurus Malkani, 2010b
V. saraiki Malkani, 2010b
Maastrichtian, Late Cretaceous
Vitakri Formation, Pakistan
Holotype- (MSM-303-2) distal metatarsal II, phalanx II-1 (~24 mm), phalanx II-2 (~25 mm), pedal ungual II, distal metatarsal III?, pedal digit III, two phalanges IV-? (~21 mm)
Diagnosis- provisionally indeterminate within Noasauridae.
Comments- Malkani proposed the name Vitakrisaurus saraiki in 2010b for a pes he had previously referred to juvenile Vitakridrinda in 2009. As interpreted by Malkani, it would have some unique features (three phalanges on digit I; four phalanges on digit II), but Malkani only explicitly diagnoses it relative to the sauropod Pakisaurus. Thus it is uncertain how Vitakrisaurus is supposed to differ from other theropods, and note it cannot be compared to any of the material referred to Vitakridrinda in any case. The photo differs markedly from the illustration, with the dorsal illustration mislabaling phalanx II-2 a claw and placing a phalanx as it appears in the medial view. The supposed metatarsal I (mislabeled 'metacarpal') is too robust and elongate, but could be a metatarsal II which would match the phalangeal count. The area above that digit (seemingly representing digits II and III) is too blurry to comment on, though the drawing would be perfectly congruent with them being complete digits III and IV. The illustrated isolated 'phalange' below the ungual in medial view may be from digit IV, since most of that digit isn't actually visible in the dorsal view. The illustration also includes a supposed scale, but whether this is supposed to derive from Vitakrisaurus or something else like a fish is never stated. Based on its size, Vitakrisaurus is more comparable to noasaurids than abelisaurids. The large ratio between phalanges II-2 and II-1 and proximally narrow metatarsal II (in dorsal view) also suggest noasaurid affinities. While II-2 is longer than Velocisaurus (compared to II-1), this varies within other species, and further comparison is not possible pending better description of this and other noasaurid pes. 

References- Malkani, 2003. First Jurassic dinosaur fossils found from Kirthar range, Khuzdar District, Balochistan, Pakistan. Geological Bulletin University of Peshawar. 36, 73-83.
Malkani, 2004. Saurischian dinosaurs from Late Cretaceous of Pakistan. in Hussain and Akbar (eds.). Abstract volume of Fifth Pakistan Geological Congress, Islamabad, Pakistan. 71-73.
Malkani, 2006a. Biodiversity of saurischian dinosaurs from the Latest Cretaceous park of Pakistan. Journal of Applied and Emerging Sciences. 1(3), 108-140.
Malkani, 2006b. First rostrum of carnivorous Vitakridrinda (abelisaurid theropod dinosaur) found from the latest Cretaceous Dinosaur Beds (Vitakri) Member of Pab Formation, Alam Kali Kakor locality of Vitakri area, Barkhan District, Balochistan, Pakistan. Sindh University Research Journal (Science Series). 38(2), 5-24.
Malkani, 2009. New Balochisaurus (Balochisauridae, Titanosauria, Sauropoda) and Vitakridrinda (Theropoda) remains from Pakistan. Sindh University Research Journal (Science Series). 41(2), 65-92.
Malkani, 2010a. Vitakridrinda (Vitakrisauridae, Theropoda) from the Latest Cretaceous of Pakistan. Journal of Earth Science. 21(Special Issue 3), 204-212.
Malkani, 2010b. Stratigraphy and mineral potential of Sulaiman (Middle Indus) basin, Pakistan. Sindh University Research Journal (Science Series). 42(2), 39-66.
Malkani, 2011. Vitakridrinda and Vitakrisaurus of Vitakrisauridae Theropoda from Pakistan. Proceedings of the 6th Symposium of IGCP 507 on Paleoclimates of the Cretaceous in Asia and their global correlation. Beijing, China. 59-66.
Malkani, unpublished. Saurischian dinosaurs from the Late Cretaceous Pab Formation of Pakistan. Geological Survey of Pakistan, Information Release. 823, 1-117.

Advance online publication and getting dates correct

We all know the issues caused by journals releasing online versions of their papers earlier than the paper versions are published.  I normally don't mind because the content is identical (though see the "Gryphognathus" vs. "Gryphoceratops" situation for an exception), but one thing it does negatively affect is that it causes lots of nomina nuda due to the ICZN's backwards Article 9.8 that doesn't accept electronic publications as valid.  I suppose technically every advance online publication naming a new taxon creates a short-lived nomen nudum, but I'm not pedantic enough to count them in most cases.  Where they matter more is when the electronic and paper versions are published in different years.  It's confused me more than once in the Database, where sometimes the online date is never corrected, sometimes the online date is never mentioned, and sometimes I happen to list both.  So to straighten it out once and for all, I've standardized my format to give all such taxa formal nomen nudum synonymies, in the comments I state what month and year the online and paper versions were published, and only list the final paper version in the references.  This should make it up on my next update, but until then, here are all the Mesozoic theropods affected, organized by journal. 

Acta Palaeontologica Polonica
- Cruxicheiros 2009 vs 2010

Cretaceous Research
- Albertonykus 2008 vs 2009
- Hollanda 2009 vs 2010
- Qiupalong 2010 vs 2011
- Bonapartenykus 2011 vs 2012
- Patagonykinae 2011 vs 2012

Historical Biology
- palmapenis 2011 vs 2012

Journal of South American Earth Sciences
- Alamitornis 2008 vs 2009

Journal of Systematic Paleontology
- Elsornis 2006 vs 2007
- Mystiornithiformes 2010 vs 2011
- Mystiornithidae 2010 vs 2011
- Mystiornis 2010 vs 2011

Naturwissenschaften
- Longirostravis 2003 vs 2004
- Skorpiovenator 2008 vs 2009
- Carcharodontosauria 2009 vs 2010
- Megaraptora 2009 vs 2010
- Neovenatoridae 2009 vs 2010

Proceedings of the Royal Society B
- Austroraptor 2008 vs 2009
- Beishanlong 2009 vs 2010
- Tianyuraptor 2009 vs 2010
- Xiongguanlong 2009 vs 2010
- Zhongjianornis 2009 vs 2010

"Syntarsus" "mexicanum"

Thanks to Pixagono, Harris, Chure and Scheetz for their combined work in finding this new theropod name.  It turns out the proper reference is-

Hernandez, 2002. Los dinosaurios en Mexico. in Gonzalez Gonzalez and De Stefano Farias (eds.). Fosiles de Mexico: Coahuila, una Ventana a Traves del Tiempo. Gobierno del Estado de Coahuila, Saltillo. 143-153.

Unfortunately, the entire section mentioning the species is-

"Otro material del grupo de los dinosaurios saurisquios (Cintura tipo reptil) ha sido determinada como una nueva especie del genero Syntarsus, llamada familia Syntarsus mexicanum, de la familia Coelophysidae: se trata de pequenos dinosaurios carnivoros de cuerpo esbelto y de 3 metros de longitud en promedia."

Or translated-

"Other material of the saurischian dinosaur group (reptile pelvic type) has been determined as a new species of the genus Syntarsus, named Syntarsus mexicanum family[sic?], of the family Coelophysidae: they are small carnivorous dinosaurs with a slender body and are 3 meters long on average."


Thus it is a nomen nudum for not including a diagnosis (ICZN 13.1.1) (the slender body and 3 meter length seem to refer to the family, not the species) or a type specimen (ICZN 16.4.1).  Harris wondered if Hernandez had planned to have an official description out by the time the book was published, but given the explicit designation of this as a new species, I don't see any evidence for that.  To the contrary, I'm curious if the apparent typo "llamada familia" used in reference to the species doesn't mean "familiar name", as in "informal name", and Hernandez didn't intend to name a new species at all.  In any case, I stand by my previous conclusion "S." "mexicanum" probably refers to the coelophysid material described by Munter and Clark (2006).  This is because the latter material comes from the locality Hernandez mentions "mexicanum" as being from ("Esta localidad descubierta en 1982 por el doctor James M. Clark") and was found to be sister to Megapnosaurus (as Syntarsus) by Munter (1999- SVP abstract and thesis).  In fact, it probably refers to the dorsals, sacrum and pelvis IGM 6624 specifically, since Hernandez also states "tambien se han identificado elementos craneales del genero Ceratosaurus", and the cranial specimen IGM 6625 was thought by Munter to be either a neoceratosaur or maniraptoran.

Probable intended holotype of "Syntarsus" "mexicanum", vertebrae and pelvis IGM 6624 in lateral view after Munter and Clark, 2006).

The Database's entry will be-

"Syntarsus" "mexicanum" Hernandez, 2002
Toarcian, Early Jurassic
La Boca Formation, Mexico
Material- (IGM 6624) partial twelfth dorsal vertebra (13.1 mm), partial thirteenth dorsal vertebra (20 mm), partial synsacrum (61.5 mm- 16.2, 12.7, 9.6, 9.6, 13.4 mm), incomplete fused pelvis
?...(IGM 6625) posterior braincase, incomplete laterosphenoid, fragments
Diagnosis- (after Munter, 1999) ilia contact dorsally on midline (may be taphonomic).
Comments- Discovered in 1994, Munter (1999) found IGM 6624 to be sister to Megapnosaurus (as Syntarsus) based on the antitrochanter projecting into the acetabulum (though this is also present in Coelophysis and Liliensternus). It differs in having ilia contact sacral neural spines two and three. The skull fragments may not belong to the same individual or taxon and were thought to be a neoceratosair or maniraptoran by Munter due to their pneumatized paroccipital roots. However, this has since been found to exist in coelophysids such as "M." kayentakatae, making the possibility it belongs to the same individual more likely. Hernandez (2002) erected a new species Syntarsus mexicanum from the locality, which is probably based on IGM 6624 since no other coelophysoid specimens have been reported from there and Munter emphasized similarity to what he called Syntarsus. However, it is a nomen nudum for not including a diagnosis (ICZN 13.1.1) or a type specimen (ICZN 16.4.1). Hernandez also mentioned cranial elements of Ceratosaurus, which are probably IGM 6625 based on Munter's comparison to neoceratosaurs. Munter and Clark later (2006) described the specimens and included IGM 6624 in Carrano et al.'s (2002) matrix where it emerged sister to Coelophysis+Megapnosaurus (excluded due to lacking fused sacral neural spines), and Rauhut's (2003) matrix where it was in the clade of Coelophysis+Megapnosaurus (the latter a chimaera of rhodesiensis and kayentakatae). They considered IGM 6625 provisionally theropod. The only potential apomorphy noted in the material has been the ilia which meet at the midline, but this may be taphonomic. Munter and Clark note that the dorsally oriented acetabulum suggests distortion, but the rugose medial ilial surface suggesting contact with the other ilium and general lack of distortion in other fossils from the locality suggests it was natural. As "mexicanum" has not been shown to be closer to Megapnosaurus than to Coelophysis, it is here retained under the name "Syntarsus" "mexicanum".
References- Clark, Montellano, Hopson, Hernandez and Reynoso, 1998. The Jurassic vertebrates of Huizachal canyon, Tamaulipas. Avances en Investigacion, Paleontologia de Vertebrados. Universidad Autonoma del Estado de Hidalgo Publicacion Especial 1. 1-3.
Munter, 1999. Two theropod dinosaur specimens from Huizachal Canyon, Mexico. Journal of Vertebrate Paleontology. 19(3), 65A.
Munter, 1999. Two theropod dinosaur specimens from Huizachal Canyon, Mexico. Masters thesis. George Washington University.
Hernandez, 2002. Los dinosaurios en Mexico. in Gonzalez Gonzalez and De Stefano Farias (eds.). Fosiles de Mexico: Coahuila, una Ventana a Traves del Tiempo. Gobierno del Estado de Coahuila, Saltillo. 143-153.
Munter and Clark, 2006. Theropod dinosaurs from the Early Jurassic of Huizachal Canyon, Mexico. In Carrano, Gaudin, Blob, Wible (eds.). Amniote paleobiology: Perspectives on the evolution of mammals, birds, and reptiles. University of Chicago Press, Chicago. 53-75.

Peters is wrong (surprise) about Herrerasaurus and a new idea about Austroraptor

It's like shooting fish in a barrel, I know, but I felt the need to correct Peters' most recent Photoshop manipulation disaster, since in encroaches on Theropoda.  Peters has a blog which mostly concerns itself with taxa outside my area of expertise, but in this case he tackles Herrerasaurus.  Taking a photo of skull PVSJ 407, he reinterprets it as having a narrow premaxilla subnarial process and elongate antorbital fossa extending to the premaillary-maxillary fenestra (making the latter a promaxillary fenestra I suppose).  Yet that skull's actually featured on Digimorph, where we can use the CT scan to test Peters' idea without the skull in hand.

Picture from Peters' blog, of Herrerasaurus skull PVSJ 407 (taken from Alcober and Martinez 2010 I think) with his interpretation of snout elements on top.  Note his antorbital fossa in dark green.

As you can see, Peters thinks the premaxilla-maxillary suture is a crack in the maxilla.

Herrerasaurus skull PVSJ 407 ct scan taken from Franzosa (2001 online).

Here's the CT scan of the skull, and notice two things.  First is that now that we only have topography to work with, Peters' antorbital fossa disappears.  The maxilla simply isn't depressed there.  Second is that the anterior edge of his supposed maxilla is actually a crack that runs through the premaxilla.  How can we tell it's definitely a crack?  It continues downward through a tooth!  I've highlighted a portion of it in the comparison pic below.

Comparison of two pictures above, with part of crack Peters interprets as a suture highlighted in red.

Just more evidence not to trust Peters' morphological interpretations or his phylogenies based on them.



But that doesn't mean professionals always interpret things correctly.  Austroraptor is a supposed unenlagiine paravian which preserves one pneumatic opening in its maxillary antorbital fossa.  Novas et al. (2009) and everyone else has interpreted it as a maxillary fenestra, which would mean Austroraptor would have lost its promaxillary fenestra like derived troodontids. However, it seems more likely to me to be a promaxillary fenestra.  First note that it is of similar shape, size and position as the promaxillary fenestrae of basal paravians such as Archaeopteryx, Sinusonasus and Velociraptor- small, lenticular, along anterodorsal border of antorbital fossa.  Maxillary fenestrae are usually placed more posteriorly, away from the anterior antorbital fossa edge and close to the antorbital fenestra.  The exception is derived troodontids, but their maxillary fenestrae are highly elongate and placed along the ventral edge of the antorbital fossa.  Second, remember that Austroraptor is odd in having a posteriorly extensive postantral wall (labeled pan in the figure below).  As a bit of explanation, the antorbital fossa surface we usually see on the maxilla is the outside wall of the maxillary antrum.  There's an inside wall running alongside it that sometimes peeks out a bit and is responsible for taxa like Scipionyx that look like they have a maxillary fossa, since the inside wall can back the maxillary fenestra.  This inside wall is called the postantral wall where it sticks out behind the lateral wall.  But another way to think of it is that the lateral wall is missing its back end, and what would be in the back end of that lateral wall if it were there?  A maxillary fenestra.  So I hypothesize Austroraptor reduced the ossification of its posterior antorbital fossa wall, merging the maxillary fenestra with the antorbital fenestra, but keeping an ancestral promaxillary fenestra morphology.  I think this hypothesis is more parsimonious than losing the promaxillary fenestra, moving the maxillary fenestra into the same position as the promaxillary fenestra, then elongating the postantral wall.

Austroraptor maxilla (center, from Novas et al., 2009) compared to dromaeosaurid maxilla (left, from Norell et al., 2006) and mostly troodontid maxillae (right, from Senter et al., 2010).  Promaxillary fenestrae circled in blue, maxillary fenestra circled in green.  For Austroraptor, I've circled the part of the postantral wall in dotted green where I think the maxillary fenestra ancestrally was before the lateral wall was reduced.

I've often said I think that Peters is right insofar as most published cladistic analyses of reptiles suck, in both taxon and character count.  Yet his own analysis is worse because it's based on imaginary morphologies.  The same is true of his constant refrain to test others' interpretations, since scientists do sometimes get things wrong.  But this must be done intelligently.

References- Franzosa, 2001 online. Herrerasaurus ischigualastensis (On-line), Digital Morphology. http://digimorph.org/specimens/Herrerasaurus_ischigualastensis/

Norell, Clark, Turner, Makovicky, Barsbold and Rowe, 2006. A new dromaeosaurid theropod from Ukhaa Tolgod (Omnogov, Mongolia). American Museum Novitates. 3545, 51 pp.

Novas, Pol, Canale, Porfiri and Calvo, 2009. A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids. Proceedings of the Royal Society B. 276(1659), 1101-1107.

Alcober and Martinez, 2010. A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina. ZooKeys. 63, 55-81.

Senter, Kirkland, Bird and Bartlett, 2010. A new troodontid theropod dinosaur from the Lower Cretaceous of Utah. PLoS ONE. 5(12), e14329.

Are Sauropod Skulls Actually Rare?

Hone recently mentioned this old piece of paleontological "common knowledge", but I wonder how true it really is.

For one, we're no longer back in the days of The Dinosauria where only ten skulls could be illustrated by McIntosh.  There have to be a few times that now at least, plus tons known from braincases and/or jaw elements.

Two, just how poorly known are skulls of other dinosaurs?  There are only four or so stegosaur taxa with known skulls, two therizinosaurs, and three alvarezsauroids, for instance.

Three, how much does it reflect the number of sauropods named from axial material as opposed to the percentage of sauropod skulls found per postcranium?  Maybe the elaborate vertebrae of sauropods make them more prone to being named from postcrania, whereas e.g. ornithopod or ceratopsian postcrania are often considered indeterminate.  I suspect if you counted all of the partial cerapod postcrania left undescribed or uncollected, their skulls would seem much more rare.

The first two questions could actually be answered statistically, once my sauropodomorph database were 'complete'.  You would need to try to include only valid taxa (nice and subjective), then find some way to represent cranial completeness (maybe on a scale of 20, where each kind of preserved skull element counts as 1, and having 20 is equivalent to a complete skull), then find the average cranial completeness number for various groups.  The third question would be more difficult, since not only would just trawling museum collections be tedious, it would leave the 'how many aren't collected' part unknown.  And just as I bet there's a bias in not collecting cerapod postcranial bits due to supposed indeterminacy, there's also a bias in not collecting sauropod fossils due to their size.