Monday, October 19, 2015

SVP 2015 Day 4

The final day.  Let's see what happened...

In another ornithischian abstract, Borinder et al. redescribe the hadrosaur Tanius.  As the authors state, it's been 86 years since the genus was described.  The only known specimen is immature and has a flexor canal on the femur.  Unfortunately, it emerges in a big polytomy with other taxa just outside Hadrosauridae.  I do wonder if excluding some of these nine taxa a posteriori might show some resolution between the remaining ones and Tanius.

Cranial elements of Tanius sinensis holotype (after Wiman, 1929).

Cuesta et al. argue that the ulnar bumps of Concavenator are homologous to the secondary remix attachment points of birds.  This was disputed separately by Naish and myself shortly after the genus was described.  I still don't see how the authors interpret the bumps as posterolateral instead of anterolateral.  I argued the structure was an intermuscular line between the flexor ulnaris and the extensor carpi radialis brevis (sensu Meers, 2003), or flexor digitorum profundus and extensor carpi ulnaris (sensu Gishlick, 2002).  Cuesta et al. state that (besides the triceps brachii which we both agree is back on the olecranon) they reconstructed the anconeus and abductor polices longus and that the bumps are not located between them.  The abductor polices longus (pronator quadratus in Meers) is a more proximodorsally located scar I agree has nothing to do with the bumps.  I think anconeus is another term for the extensor carpi ulnaris, based on Gishlick's figure of Corvus and Hudson and Lanzillotti's (1964) description.  So with the caveats that there seems to be no consensus for muscle names or homology between crocodylians and birds, I don't think Cuesta et al. had the same muscles in mind as I did.

Fortner reports "parts of an associated postcranial skeleton of a small theropod dinosaur recently collected from the uppermost Aguja Formation."  This is another frustrating example of the information-bereft abstract, with the first twelve lines devoted to introduction and background knowledge.  The only other bit of information is- "The specimen exhibits some unique features, but is compatible with identification as either Troodontidae or Dromaeosauridae."  This is very intriguing, as while both eudromaeosaur and troodontine teeth are known from the Aguja, we have Richardoestesia and Paronychodon from there too.  As I think these are microraptorine and basal troodontid respectively, this specimen could fit the bill.  Did anyone get more details?

The only published non-dental remains attributed to Paronychodon- a partial dentary IPFUB GUI D 1 in A. medial, B. dorsal, and C. lateral views (after Zinke and Rauhut, 1994).  It does differ from later Paronychodon in having distal and sometimes mesial serrations.

Harding et al. have the non-dinosaurian abstract I think could be most important to dinosaur studies.  They examined all "published characters for discriminating Sceloporus from the related iguanian lizards Uta and Urosaurus, and for discriminating among species of Sceloporus" for 14 species, "11 of [which] had more than ten individual skeletal specimens, and for four of them sample sizes exceeded 50 specimens."  Perhaps astonishingly "almost all characters published in the literature to identify fossil specimens have no power to discriminate reliably between Uta, Urosaurus, and Sceloporus, nor between species of Sceloporus we examined."  In our field where most species are only known from single specimens, and most known from multiple specimens don't have more than one or two described in detail, what does this mean for our autapomorphy lists?

Holtz et al. report more information on an Anzu specimen (anyone know the collection number?) they announced last year.  Interestingly, only distal tarsal IV is fused to the unfused metatarsus, and "a pair of pronounced cruciate ridges on the plantar surface of metatarsal III" are present as in Elmisaurus but don't extend as far proximally.  This would make it intermediate in pedal morphology between Chirostenotes and Elmisaurus

Maddin et al. present a hypothesis based on the development of skull roof bones in mice and chickens.  In mice (and axolotls) the suture between the frontal and parietal corresponds to the boundary between the neural crest and mesoderm in the embryo.  In chickens, the latter embryonic boundary is within the frontal itself.  Thus the authors suggest the avian 'frontal' is actually a fused frontal and parietal, while the avian 'parietal' is actually a postparietal.  They say that hypothesis "is also supported phylogenetically where data from the fossil record reveal separate frontal, parietal, and postparietal bones are present in all stem lineages of extant taxa, including that of birds (e.g., the stem archosaur Euparkeria)."  The problem I see is that the postparietal in basal archosauriforms is a tiny wedge between the parietals and supraoccipital, while the parietals have the same topological relationships and morphology in these basal archosauriforms that they do in basal dinosaurs.  It seems more likely to me that this is a case like manual homology where the developmental process itself evolves, so that somewhere on the sauropsid line, the neural crest-mesoderm boundary moved into the frontal.  Also interesting would be to know what the state in lepidosaurs and crocodylians is.

Comparison of skull roof in dorsal view of- left, Erythrosuchus africanus (after Gow, 2003); center, Ornithosuchus longidens (after Walker, 1964), and right, Herrerasaurus ischigualastensis (after Sereno and Novas, 1993).  Parietal is blue, postparietal is red.  Maddin et al. suggest the red at left is homologous to the blue at right.

Mannion et al. redescribe the famous 'French Bothriospondylus' (MNHN coll.), presumably based on Moine's (1999) thesis.  It's great that we're getting all of the historical Bothriospondylus material redescribed in the last decade.

McFeeters et al. do the important job of reevaluating Struthiomimus specimens.  Little known to most, the holotype is extremely fragmentary, with most information coming from Osborn's AMNH 5339, Nicholls and Russell's UCMZ 1980.1 and the new RTMP 90.26.1. The authors find "a relatively small partial skeleton from the lower Dinosaur Park Formation" (which based on listed elements must be ROM 1970) to belong to a new taxon of ornithomimid based on several autapomorphies.  This specimen forms the basis of the dorsal snout in Russel's (1972) and Paul's (1988) cranial reconstructions, making those composites.  Another specimen shares some pelvic characters with Qiupalong, perhaps relating to a Dinosaur Park astragalus reported by McFeeters et al. in last year's SVP abstract. 

Nesbitt et al. seem set to provide a detailed description of Asilisaurus, after the original tabloid announcement.  Interestingly, Agnosphitys is said to a basal silesaurid as well, which is the fourth proposed identification for the genus.  Add this to Agnolin's (2015) Jornadas Argentinas abstract proposing Pisanosaurus belongs to the clade, and its membership is expanding markedly.

We also get yet another description of Nothronychus' braincase.  Far be it for me to complain about having too many descriptions of a taxon, but this one specimen of one taxon was described in 2005, 2012 and 2013, and now we'll probably get a fourth portion next year or so.  At least this new abstract is about the previously unrecognized anterior portion, but I'd rather have that time and effort go towards... say "Zunityrannus" or describing the Bayan Shiree therizinosaur postcrania.  Smith et al. report that "there is a supraorbital evagination in this specimen that is currently interpreted as accommodating a well-developed nasal gland in the frontal.  This development has been observed in some other archosaurs, especially marine birds, where it is associated with salt excretion and is consistent with a beach or other evaporitic paleoenvironmental interpretation."  So let's all start our All Yesterdays style marine therizinosaur pics.

Finally for this year, Sullivan et al. report a 'sphenosuchian' specimen sister to Junggarsuchus.  This has the interesting mix of cursorial features with a webbed hand and distal tail sheathed with armor. 

References- Wiman, 1929. Die Kreide-Dinosaurier aus Shantung. Palaeontologia Sinica (series C). 6, 1-67.

Hudson and Lanzillotti, 1964. Muscles of the pectoral limb in galliform birds. The American Midland Naturalist. 71(1), 1-113.

Walker, 1964. Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosaurs. Philosophical Transactions of the Royal Society of London, seies B. 248(744), 53-134.

Russell, 1972. Ostrich dinosaurs from the Late Cretaceous of western Canada. Canadian Journal of Earth Sciences. 9, 375-402.

Paul, 1988. Predatory Dinosaurs of the World. Simon & Schuster: New York. 464 pp. 

Sereno and Novas, 1993. The skull and neck of the basal theropod Herrerasaurus ischigualastensis. Journal of Vertebrate Paleontology. 13, 451-476.

Zinke and Rauhut, 1994. Small theropods (Dinosauria, Saurischia) from the Upper Jurassic and Lower Cretaceous of the Iberian Peninsula. Berliner Geowissenschaftliche Abhandlungen. E 13, 163-177.

Moine, 1999. Datation, condition de depot et position phylogenetique de 'Bothriospondylus madagascariensis' (Damparis,
Jura, France). MS thesis, Memoires de Maıtrise Magistere Sciences de la Terre ENS-Lyon.

Gishlick, 2002. The functional morphology of the forelimb of Deinonychus antirrhopus and its importance for the origin of avian flight. PhD thesis, Yale University. 142 pp.

Gower, 2003. Osteology of the early archosaurian reptile Erythrosuchus africanus Broom. Annals of the South African Museum. 110(1), 1-88.

Meers, 2003. Crocodylian forelimb musculature and its relevance to Archosauria. The Anatomical Record. Part A, 274A, 891-916.

Agnolin, 2015.  Nuevas observaciones sobre Pisanosaurus mertii Casamiquela, 1967 (Dinosauriformes) y sus implicancias taxonomicas. XXIX Jornadas Argentinas de Paleontologia de Vertebrados. Libros de Resumenes. 13-14.

Friday, October 16, 2015

SVP 2015 Day 3

Time for day three.  If I were in Dallas, I'd be waking up early for Technical Session X.

Carrano and Choiniere reexamine Ceratosaurus' forelimb based on the holotype.  The whole thing could use redescription since Gilmore's last one 95 years ago.  While they state "These new data are consistent with the placement of Ceratosaurus as close to (or within) Abelisauroidea", an abelisauroid Ceratosaurus is impossible as Ceratosauroidea predates Abelisauroidea, without even getting into phylogenetic nomenclature. 

Hey, we get more Dromiceiomimus feathers.  van der Reest et al. report on a new specimen preserving feathers on the proximal thigh and dorsal tail, but not ventral tail or distal hindlimb.  The feathers are also branched, moving this trait to the base of Maniraptoriformes.  As the feathers have rachis but lack barbules, it seems Prum's Stage IIIa was correct.

Segnosaurus galbinensis radius and ulna (paratype IGM 100/83), courtesy of Zanno.

Kobayashi et al. describe a new therizinosaur specimen from the Bayan Shiree Formation, where Segnosaurus, Erlikosaurus and Enigmosaurus come from.  While it's notable for having a reduced metacarpal III (and thus perhaps reduced third manual digit), none of the three named genera from that formation preserve enough manual material to evaluate their condition.  The new specimen is potentially comparable to Enigmosaurus and Segnosaurus in that all preserve the radius and ulna.

Funston and Currie report on their fairly complete Horseshoe Canyon caenagnathid.  Supposedly having cervicals "distinct from Epichirostenotes", an "articular ridge is intermediate in size and form between Caenagnathus collinsi" and sternbergi, and autapomorphic manual proportions, it should be useful for resolving caenagnathid taxonomy.  In addition to the expected anatomical details, ulnar "feather scars" are said to be present.

Lu et al. discuss the billionth new oviraptorid from the Nanxiong Formation.  This one's based on at least a skull and is similar to Khaan.  Some of these things have got to be synonymous

Saurornitholestes has been the ubiquitous but rarely described Late Cretaceous American dromaeosaurid.  We've had RTMP 88.121.39 and MOR 660 known since 1988 and 1990 respectively, but both are only mentioned in passing in papers.  Now we have a new almost complete specimen discovered in 2014 (did anyone who saw the talk catch the specimen number?) that includes a skull.  Is the Saurornitholestes osteology finally at hand?

Perhaps the most unusual theropod abstract is from Sorkin, describing a phylogeny for tetanurines.  I'm not sure if it's based on a quantitative analysis or just the noted 'key characters', but it's not similar to the current consensus.  From the abstract, his topology and taxonomy seems to be-


            |--Acrocanthosauridae (incl. Eocarcharia)

Brings you back to the early 90s, doesn't it?  Note the new clade name Euavetheropoda, said to be distinguished by a robust dorsal quadratojugal process.  In any case, the accepted phylogenetic definition for Avetheropoda would put it at the Allosauridae+Coelurosauria node, making Euavetheropoda unintuitively more inclusive. 

Wills describes sixteen teeth from the Bathonian Forest Marble Formation of England.  When analyzed, these plot with dromaeosaurids.  He states "This pushes back the origin of dromaeosaurids from the Kimmeridgian to the Bathonian", but Metcalf and Walker described teeth from the Bathonian Chipping Norton Formation of England as dromaseosaur-like back in 1994.  Maybe these new ones are more securely identified.

Dromaeosaurid-like tooth (GLRCM G.51422) from the Bathonian Chipping Norton Formation in lingual (A), labial (B) and basal (C) views (after Metcalf and Walker, 1994).
Just one more day to go, with quite a few interesting abstracts tomorrow.

Reference- Metcalf and Walker, 1994. A new Bathonian microvertebrate locality in the English Midlands. In Fraser and Sues (eds.). In the Shadow of the Dinosaurs- Mesozoic Small Tetrapods. Cambridge University Press. 322-332.

Thursday, October 15, 2015

SVP 2015 Day 2

And we're on to day two.  Something I noticed about this year's and last year's abstracts is just how many of them are already published in official format by the time the meeting happens (yet another reason the embargo is silly).  I gather one of the big issues facing SVP is how many talks and papers there are, leading to greater expense, more parallel sessions, etc..  If the dinosaur abstracts are any indication, you could cut out a third of them by excluding those that will be published by September.

Pritchard created a new matrix to test the relationships of Sauria, but alas this is one of those abstracts that doesn't actually contain much information.  The most it says is that Protorosauria is para/polyphyletic, which everyone agrees with by now.  I would ask that if your SVP abstract is based on a phylogenetic analysis, please devote at least a couple sentences to describing the topology you found.  Otherwise it's just a tease and I learn nothing.

This was a great SVP for ornithischians.  We've had Arbour revise ankylosaurids, and now Burns is doing the same for Campanian-Maastrichtian North American nodosaurids. He finds Denversaurus is a valid taxon, sister to Panoplosaurus.  So that's another genus from your 1980s dino encyclopedias to dust off.

Denversaurus.  What?  That's not right?...

Continuing the ornithischian train, Barta and Norell report on new specimens of Haya.  The interesting thing here is that they performed two analyses- one with each specimen coded as a separate OTU, and the other with one Haya OTU that was coded as polymorphic when specimens differed.  In the first, Haya emerged as a basal thescelosaurid, but in the second it was a basal neornithischian.  This is presumably because PAUP/TNT finds it most parsimonious to choose a mix of states for the polymorphic characters that isn't found in any actual specimen.  It's concerning because being a lumper myself, I code e.g. Microraptor and Archaeopteryx as single OTUs.  Is that affecting their relationships in my analyses? 

Shelley et al.'s abstract is an example of two things I like.  First, figuring out where all of those extinct mammal groups go using a molecular scaffold for the topology.  Second, actually describing the results of the study- "Our phylogenetic analysis places "triisodontids" as a basal member of Euungulata within Laurasiatheria. "Triisodontidae" forms a paraphyletic stem of Mesonychia with Oxyclaenus most closely related to a monophyletic Mesonychia.  "Triisodontids" plus Mesonychia are closely related to a clade comprised of the arctocyonids Mimotricentes, Deuterogonodon and Chriacus."  Ahhh, actual information...

Besides the usual morass of Yixian and Jiufotang birds (including Parapengornis, which I think is just Pengornis), we get another specimen from the lower member of the Huajiying Formation.  This earlier horizon has otherwise only yielded Confuciusornis zhengi, Protopteryx, Eopengornis and Archaeornithura.  Hu et al.'s new enantiornithine is said to have a Liaoningornis-like sternum, which could cement the affinities of that genus. 

The Norman-Barrett team's on the basal ornithischian case again, this time with Baron et al.'s redescription of Lesothosaurus postcrania.  This is needed, as Sereno (1991) mostly described the skull and thus we've had to depend on Thulborn's work from 43 years ago.  They find Stormbergia to be based on older individuals of Lesothosaurus, which as a lumper, does not surprise me.  The genus emerges as a basal neornithischian.  This should be a good paper once it's published.

Holotype of "Morosaurus" agilis (USNM 5384) posterior skull and anterior cervicals in left lateral view (after Gilmore, 1907).

Finally, Whitlock and Wilson redescribe the hitherto enigmatic "Morosaurus" agilis.  Based on a braincase and anterior cervicals, it turns out to be a diplodocid.  While apparently not Apatosaurus (in which the abstract seems to include Brontosaurus) or Galeamopus, the newly exploded Morrison Diplodocidae leaves open numerous possible identifications- Supersaurus, Amphicoelias, Kaatedocus, Barosaurus, Diplodocus...  I'm not sure I believe its affinities can't be narrowed down further.  For instance, Lovelace et al. (2007) stated small cervical pleurocoels were diagnostic for Supersaurus, and agilis has large pleurocoels.  Tschopp and Mateus (2013) proposed numerous characters to distinguish Kaatedocus from other diplodocids, including a postorbitally restricted squamosal that agilis seems to have, and a postparietal foramen agilis seems to lack.  Maybe published characters have issues that I'm not aware of as a theropod worker, or maybe Gilmore's description is misleading, but I find hard to believe that something as complex as a braincase and posterior skull can't be distinguished between Kaatedocus and Diplodocus (even if Amphicoelias and Barosaurus can't be compared).

Join me again tomorrow, when we open with those sweet, sweet theropod abstracts...

References- Gilmore, 1907. The type of the Jurassic reptile Morosaurus agilis redescribed, with a note on Camptosaurus. Proceedings of the United States National Museum. 32(1519), 151-165.

Sereno, 1991. Lesothosaurus, "fabrosaurids," and the early evolution of Ornithischia. Journal of Vertebrate Paleontology. 11(2), 168-197.

Lovelace, Hartman and Wahl, 2007. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional Rio de Janeiro. 65, 527-544.

Tschopp and Mateus, 2013. The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs. Journal of Systematic Palaeontology. 11, 853-888.

Wednesday, October 14, 2015

SVP 2015 Day 1

While again too poor to attend SVP, I thought I would provide my thoughts on the abstracts that interest me like I did last year.  The abstracts book can be download free at this link.  When adding abstracts to the Database, I noticed an issue that's been constant throughout the years- the titles are in UPPERCASE.  This makes copying them useless, which means everyone citing abstracts has to rewrite them.  This can only lead to more typos and serves no obvious purpose since the titles are already bolded to distinguish them from the rest of the text.  Does anyone else agree they should have normal capitalization?

This year there are no less than three abstracts marked as WITHDRAWN.  One is by Egberts and concerns wearing gloves when handling specimens to prevent skin oils damaging the fossils.  Another is by Spindler, about a supposed Carboniferous therapsid specimen.  The third by Parsons and Parsons involves aerial forelimb motion in Bambiraptor and Deinonychus.  I wonder why these three abstracts didn't make it.

Wilson reports that of three histologically sampled Pteranodon specimens, the largest and smallest are rather mature, while the medium-sized one is immature.  While she interprets this to mean "there may be a large amount of adult body size variation in Pteranodon" or possibly that "the smallest specimen sampled is from a large Nyctosaurus specimen", Peters' idea of taxonomic instead of ontogenetic variation in Pteranodon seems viable too.  Is this a case of Peters being right?

Andres (and posthumously Langston) signal the beginning to the end of the deplorable situation pterosaur workers have been in where Quetzalcoatlus' holotype has been inaccessible due to the TMM embargoing it for decades.  All it took was the eventual death of the person monographing it.  :|  Now if we can just get Pelecanimimus out of the same rut, so that those who have the thesis describing it will distribute it and allow others to photograph the material described over two decades ago...

Frontals of Bellusaurus sui referred specimen IVPP V17768.7 (left; after Mo, 2013), Europasaurus holgeri referred specimen DFMMh/FV 162 (center; after Marpmann et al., 2015), and Camarasaurus lentus referred specimen CM 11338 (right; after Gilmore, 1925) showing two characters reported by Moore et al. as shared between the former two genera- elongate frontal and deep orbital concavity in frontal. 

Moore et al. report on new Bellusaurus cranial elements, juvenile like the previously known material.  Interestingly, these support a macronarian position, and close relationship with Europasaurus.  No update on the oft-hypothesized synonymy with Klamelisaurus, as that genus only preserves teeth and postcrania.

Finally, we have the abstract supposedly authored by Chinzorig, Kobayashi, Tsogtbaatar, Mahito, Rinchen and Shigeru...?  Someone messed up somewhere, because of course the actual authorship using surnames should be Tsogtbaatar, Kobayashi, Tsogtbaatar, Watabe, Barsbold and Suzuki.  This one's going to be tedious to find/cite in the future.  The find itself is a diagnostic ornithomimid tarsus and pes from the Djadokhta Formation of Mongolia, unfortunately not comparable to the previously described cranial and vertebral material (IGM 100/987 and 100/1245) from that formation.

Join me tomorrow for Day 2 talks and posters...

References- Gilmore, 1925. A nearly complete articulated skeleton of Camarasaurus, a saurischian dinosaur from the Dinosaur National Monument. Memoirs of the Carnegie Museum. 10, 347-384.

Mo, 2013. Bellusaurus sui. Topics in Chinese Dinosaur Paleontology. Henan Science and Technology Press. 155 pp.

Marpmann, Carballido, Sander and Knötschke, 2015. Cranial anatomy of the Late Jurassic dwarf sauropod Europasaurus holgeri (Dinosauria, Camarasauromorpha): Ontogenetic changes and size dimorphism. Journal of Systematic Palaeontology. 13(3), 221-263.

Thursday, September 17, 2015

Scaphonyx, Hyperodapedon minor and a site update

The final example of four-ex-saurischians is Scaphonyx fischeri.  A big thanks to Mike Benton for helping me with Hyperodapedon minor.  Today The Theropod Database was also updated, and the next update in October will feature all the new SVP 2015 information.

Hyperodapedon Huxley vide Murchison, 1858
= Stenometopon Boulenger, 1904
= Scaphonyx Woodward, 1907
= Cephalastron Huene, 1926
= Cephalonia Huene, 1926
= Cephalostronius Huene, 1926
= Scaphonychimus Huene, 1926
= Macrocephalosaurus Tupi-Caldas, 1933
= Paradapedon Huene, 1938
= Supradapedon Chatterjee, 1980
Definition- (Hyperodapedon gordoni < - Teyumbaita sulcognathus) (Langer and Schultz, 2000)
References- Murchison, 1858. On the sandstones of Morayshire (Elgin, &c.) containing reptilian remains; and on their relations to the Old Red Sandstone of that country. Quarterly Journal of the Geological Society of London. 15, 419-439.
Boulenger, 1904. On reptilian remains from the Triass of Elgin. Philosophical Transactions of the Royal Society of London B. 196, 175-189.
Woodward, 1907. On some fossil reptilian bones from the state of Rio Grande do Sul. Revista do Museu Paulista. 7, 46-57.
Huene, 1926. Gondwana-Reptilien in Südamerika. Palaeontologia Hungarica. 2, 1-108.
Tupi-Caldas, 1933. Contribuição ao estudo do fossil da Alemoa, Município de Santa Maria, Rio Grande do Sul. In Tupi-Caldas (ed.). Curso Geral de Mineralogia e Geologia, aplicada ao Brasil. Edições da Livraria do Globo. 333-339.
Huene, 1938. Stenaulorhynchus, ein Rhynchosauridae der ostafrikanischen Obertrias. Nova Acta Leopoldina. 1938, 83-121.
Chatterjee, 1980. The evolution of rhynchosaurs. Memoires de la Societe Geologique de France, Nouvelle Serie. 139, 57-65.
Langer, 1996. Rincossauros sul-brasileiros: Historico e filogenia. Masters thesis, Universidade Federal do Rio Grande do Sul. 361 pp.

 H. fischeri (Woodward, 1907) Whatley, 2005
= "Scaphonyx fischeri" White, 1906
= Scaphonyx fischeri Woodward, 1907
Carnian, Late Triassic
Alemoa Member of the Santa Maria Formation, Brazil
- (BM R-5033) two cervical centra, dorsal centrum, central fragment, phalanx III-1, phalanx III-2, phalanx III-3, manual ungual III, pedal ungual I

Comments- The holotype was discovered in 1902, and initially announced by Woodward in 1903 before being described and named by him in 1907. White (1906) first published the name in a note in Science, but did not provide a description or definition (ICZN Article 12.1), making the name a nomen nudum. Woodward (1907) identified Scaphonyx as a Euskelosaurus-like dinosaur based on several characters. First, the dorsal centrum lacks a parapophysis, supposedly unlike 'anomodonts' (under which he included pareiasaurs, procolophonids and therapsids), but rhynchosaurs (which Woodward classified as rhynchocephalians) possess the same state as Scaphonyx. Second, the cervical supposedly resembled Euskelosaurus, but this was based on a specimen (BMNH R2791) now referred to Erythrosuchus (as foreseen in Woodward's postscript). The large pedal ungual I with obliquely curved unguals was compared favorably to sauropods, but is also present in derived hyperodapedontines. Finally, a pedal digit with four phalanges was considered similar to dinosaurs and unlike 'anomodonts', but rhynchosaurs have three pedal digits with this many phalanges as well, and the digit closely matches manual digit III of Alemoa Hyperodapedon. Woodward's 1907 paper was actually written in 1904, and when reprinted in 1908 he included a postscript which recognized BMNH R2791 as non-dinosaurian. As he compared it favorably to Erythrosuchus (considered by Woodward to resemble both 'anomodonts' and 'belodonts'- the latter containing parasuchians and aetosaurs), Woodward now considered Scaphonyx an 'anomodont'.
Huene (1908) noted Scaphonyx was unlike dinosaurs in the presence of postaxial intercentra, cervical diapophyses and parapophyses which are placed high on the vertebra, and dissimilar unguals. He suggested it might be a therapsid or parasuchian. In 1911, Huene proposed Scaphonyx and Erythrosuchus were members of his new 'thecodont' group Pelycosimia, which continued through 1926 when he gave Scaphonyx its own family. In 1929, Huene finally recognized the similarity between Scaphonyx and rhynchosaurs, assigning the genus to the group.

Holotype of Scaphonyx fischeri (BM R-5033).  Upper left- posterior cervical centrum in anterior and right lateral view.  Upper right- anterior dorsal centrum in anterior and right lateral view.  Lower left- ?manual digit III in dorsal and ventral view, phalanx III-1 is rotated 90 degrees. Lower right- pedal ungual I in medial, proximal and lateral view.  All to scale (after Woodward, 1908).
While long considered a valid genus of rhynchosaur, Langer (1996; published in Langer and Schultz, 2000a) proposed Scaphonyx fischeri's holotype is indeterminate, as multiple species are known from the Alemoa member (mariensis, sanjuanensis, and what would be named huenei) which have only been distinguished using cranial characters. Although huenei is not known from postcrania (so can't be compared to fischeri), mariensis and sanjuanensis have not had their vertebral or pedal anatomy compared in detail in the published literature. Indeed, Alemoa rhynchosaurs have not had their postcrania well described in over seventy years. Given these facts and that I lack access to both Langer's thesis and mariensis' original and only published description, I only consider it provisionally indeterminate here. Additional specimens assigned to S. fischeri by Huene (1926, 1942) have been considered indeterminate or referrable to S. sanjuanensis (Langer and Schultz, 2000b; Montefeltro, 2008; Langer, pers. comm. 2015).

References- Woodward, 1903. On some dinosaurian bones from south Brazil. Geological Magazine. 10(11), 512.
White, 1906. Geology of south Brazil. Science. 24(612), 377-379.
Woodward, 1907. On some fossil reptilian bones from the state of Rio Grande do Sul. Revista do Museu Paulista. 7, 46-57.
Huene, 1908. Die Dinosaurier der Europäischen Triasformation mit berücksichtigung der Ausseuropäischen vorkommnisse. Geologische und Palaeontologische Abhandlungen. Supplement 1(1), 1-419.
Woodward, 1908. On some fossil reptilian bones from the state of Rio Grande do Sul. Geological Magazine. 5(6), 251-255.
Huene, 1911. Über Erythrosuchus, Vertreter der neuen Reptil-Ordnung Pelycosimia. Geologische und Paläontologische Abhandlungen. 10(1), 1-60.
Huene, 1926. Gondwana-Reptilien in Südamerika. Palaeontologia Hungarica. 2, 1-108.
Huene, 1929. Über Rhynchosaurier und andere Reptilien aus den Gondwana-Ablagerungen Südamerikas. Geologie und Palaeontogie Abhandlungen. 17, 1-61.
Huene, 1942. Die fossilen Reptilien des sudamerikanischen Gondwanalandes. C. H. Beck, Munich. 342 pp.
Langer, 1996. Rincossauros sul-brasileiros: Historico e filogenia. Masters thesis, Universidade Federal do Rio Grande do Sul. 361 pp.
Langer and Schultz, 2000a. Rincossauros-herbivoros cosmopolitas do Triassico. In Holz and de Ros (eds.). Paleontologia do Rio Grande do Sul. Porto Alegre. Ediitora da Universidade, CIGO/UFRGS, Brazil. 246-272.
Langer and Schultz, 2000b. A new species of the Late Triassic rhynchosaur Hyperodapedon from the Santa Maria Formation of south Brazil. Palaeontology. 43, 633-652.
Whatley, 2005. Phylogenetic relationships of Isalorhynchus genovefae, the rhynchosaur (Reptilia, Archosauromorpha) from Madagascar. PhD thesis, University of California. 276 pp.
Montefeltro, 2008. Inter-relações filogenéticas dos rincossauros (Diapsida, Archosauromorpha). Masters thesis, Universidade de Sao Paulo. 203 pp.

As a bonus, since I make a short entry for every species of a genus that I use on The Theropod Database, I came across Hyperodapedon minor.  Barely any info was present online, or in the literature.

H. gordoni Huxley vide Murchison, 1858
?= Hyperodapedon minor Burckhardt, 1900b
= Stenometopon taylori Boulenger, 1904
Early Norian, Late Triassic
Lossiemouth Sandstone Formation, Scotland
- The citation for Murchison (1858) is often listed incorrectly, misspelled 'Murchinson', cited as 1859, with an erroneous title, and pagination from Huxley's 1869 paper.
Hyperodapedon minor- This species was established by Burckhardt (1900b; page 492) for two small maxillae and a mandible from Warwickshire which were mentioned in a footnote by Huxley (1869) as H. gordoni. Only a few statements were made about H. minor in Burckhardt's work, with the only proposed distinguishing character being a more posteriorly extensive dentary tooth row than H. gordoni. The taxon has been virtually ignored in the literature since, though Huene (1942) did say its distinctiveness from H. gordoni is unfounded and that it should probably be rejected. Discussion with Benton (pers. comm 2015) indicates Burckhardt only visited the BMNH, though no specimens there were indicated as belonging to this species. Based on Benton's unpublished thesis notes, I believe BMNH R3150 (listed as "Partial skull 18 pieces, some fitting: palate views of mx, pal etc - small animal") is the best possibility for being H. minor's holotype, though it's possible the holotype has remained unnoticed or become lost. Regardless, the fact all diagnostic Lossiemouth Sandstone rhynchosaurs have been referred to H. gordoni suggests H. minor is similarly referrable.
References- Murchison, 1858. On the sandstones of Morayshire (Elgin, &c.) containing reptilian remains; and on their relations to the Old Red Sandstone of that country. Quarterly Journal of the Geological Society of London. 15, 419-439.
Huxley, 1869. On Hyperodapedon. Quarterly Journal of the Geological Society of London. 25, 138-152.
Burckhardt, 1900a. On Hyperodapedon gordoni. Geological Magazine. 7(12), 529-535.
Burckhardt, 1900b. On Hyperodapedon gordoni. Geological Magazine. 7(37), 486-492.
Boulenger, 1904. On reptilian remains from the Triass of Elgin. Philosophical Transactions of the Royal Society of London B. 196, 175-189.
Huene, 1942. Die fossilen Reptilien des sudamerikanischen Gondwanalandes. C. H. Beck, Munich. 342 pp.
Benton, 1981. The Triassic reptile Hyperodapedon from Elgin, functional morphology and relationships. PhD thesis, University of Newcastle upon Tyne. [? pp].

Tuesday, September 1, 2015

Plesiosaurs that used to be dinosaurs

Several marine reptiles have been confused for dinosaurs in the past, from sea lizard "Yezosaurus", to ichthyosaur Rachitrema, to sea turtle Pneumatoarthrus.  But what about plesiosaurs?  These are the specimens that I know of which have been previously assigned to saurischians.  If this has taught me anything, it's that there are a TON of century-old plesiosaur taxa that need to be reexamined.

unnamed thalassophonean (Hahnel, 1988)
Middle Kimmeridgian, Late Jurassic
La Caja Formation, Mexico
- (UANL-FCT-R2; The Monster of Aramberri) (~15 m) jaw fragment (lost), cranial fragments, nine cervical vertebrae, seven partial pectoral vertebrae (90-105 mm), rib fragments, gastralium?, axial material, incomplete scapula, incomplete coracoids, humerus, pelvis, femora (~1.2 m), epipodials

Jaw fragment of thalassophonean UANL-FCT-R2 which caused Hahnel to mistake it for a theropod (after Buchy, 2007).

Comments- Hahnel (1988) initially referred this specimen to Theropoda based on the large size and carnivorous teeth. Buchy et al. (2003) reidentified it as Pliosauridae indet. based on the pectoral section and lost snout. Frey et al. (2006) announced the recovery of much of the rest of the specimen, preliminary results which are given in Buchy's (2007) thesis. Buchy retained it as Pliosauridae indet., which can be narrowed to Thalassophonea indet. given its late age. Once more of the specimen is prepared, it may be possible to assign further.
References- Hahnel, 1988. Hallazgo de restos de dinosaurio en Aramberri, N.L., Mexico. Actas de la. Facultad de Ciencias de la Tierra, U.A.N.L. 3, 245-250.
Buchy, Frey, Stinnesbeck and Lopez-Oliva, 2003. First occurrence of a gigantic pliosaurid plesiosaur in the Late Jurassic (Kimmeridgian) of Mexico. Bulletin de la Societe Geologique de France. 174(3), 271-278.
Frey, Stinnesbeck and Buchy, 2006. The Monster of Aramberri. German Research. 27(3), 4-7.
Buchy, 2007. Mesozoic marine reptiles from north-east Mexico: Description, systematics, assemblages and palaeobiogeography. PhD thesis, Universitat Karlsruhe. 89 pp.

unnamed probable brachauchenine (Knoll, Collete, Dubus and Petit, 2000)
Early Albian, Early Cretaceous
Sables verts, France
- (Petit coll.) posterior dorsal centrum (107 mm)

Posterior dorsal centrum (Petit coll.) of a ?brachauchenine pliosaurid first published as a sauropod caudal by Knoll et al., in anterior (A), left lateral (B), posterior (C) and ventral (D) views (after Buffetaut et al., 2005).

Comments- Knoll et al. (2000) originally described this as a possibly brachiosaurid sauropod proximal caudal, but it was reidentified by Buffetaut et al. (2005) as a pliosaurid dorsal. Given its age, it is probably referrable to Brachaucheninae, but is likely to be indeterminate.
References- Knoll, Collete, Dubus and Petit, 2000. On the presence of a sauropod dinosaur (Saurischia) in the Albian of Aube (France). Geodiversitas. 22, 389-394.
Buffetaut, Collete, Dubus and Petit, 2005. The "sauropod" from the Albian of Mesnil-Saint-Père (Aube, France): A pliosaur, not a dinosaur. Carnets de Géologie. 2005/01, 1-5. 

Pliosaurus Owen, 1841 sensu Owen, 1842
?= Spondylosaurus Fischer de Waldheim, 1845
?= "Tapinosaurus" Lennier, 1887
= Stretosaurus Tarlo, 1959
= Strongylokrotaphus Novozhilov, 1964
Comments- This was originally erected as a subgenus of Plesiosaurus, spelled Pleiosaurus (Owen, 1841). As Benson et al. (2013) state, ICZN Article 33.3.1 indicates Pliosaurus is an incorrect subsequent spelling but should be retained as it has been "in prevailing usage and is attributed to the publication of the original spelling." Owen (1841) raised it to genus level. See Knutsen (2012) and Benson et al. (2013) for differing views on species validity.
References- Owen, 1841. Odontography; or a treatise on the comparative anatomy of the teeth, I Part 11. Dental system of reptiles. Hippolyte Bailliere, London. 179-295.
Owen, 1842. Report on British fossil reptiles. Part II. Report of the Eleventh Meeting of the British Association for the Advancement of Science. 60-204.
Fischer de Waldheim, 1845. Notice sur le Spondylosaurus genre de saurien fossile de l'oolithe de Moscow. Aus dem Bulletin de la Societe Imperiale des Naturalistes de Moscou. 18, 343-351.
Lennier, 1887. Études paléontologiques. Description des fossiles du Cap de la Hève. Bulletin de la Société Géologique de Normandie. 1886(12), 17-98.
Tarlo, 1959. Stretosaurus gen. nov., a giant pliosaur from the Kimmeridge Clay. Palaeontology. 2, 39-55.
Knutsen, 2012. A taxonomic revision of the genus Pliosaurus (Owen, 1841a) Owen, 1841b. Norwegian Journal of Geology. 92, 259-276.
Benson, Evans, Smith, Sassoon, Moore-Faye, Ketchum and Forrest, 2013. A giant pliosaurid skull from the Late Jurassic of England. PLoS ONE. 8(5), e65989.

Not ever thought to be a dinosaur, but how often do you get to see the holotype of Spondylosaurus frearsi?  This probable Pliosaurus specimen from the Late Jurassic of Russia hasn't been redescribed in 170 years, and according to Storrs et al. (2000) is of unknown whereabouts.  Posterior cervical centrum in (left to right) ventral, left lateral, anteroventral and oblique anterodorsolateral views (after Fischer de Waldheim, 1845).

P. rigauxi (Sauvage, 1874) new comb.
= Cetiosaurus rigauxi Sauvage, 1874
Middle Tithonian, Late Jurassic
Portel, France
- (MHNL coll.; = MHNB 233) posterior cervical centrum (85 mm)

Comments- Sauvage (1874) initially described this as a posterior cervical centrum of a new Cetiosaurus species, notable for its short proportions. In 1895 he referred it to Pliosaurus sp. in a brief note, which would technically make it Pliosaurus rigauxi. That combination has never been used to my knowledge, however. Sauvage (1902) later referred the specimen to Pliosaurus grandis without stated justification. P? grandis is based on a scapula and three unassociated propodials from the Kimmeridgian of England which were poorly described and lost, so there's no reason to connect them to rigauxi. No more recent studies have been published, and the specimen has never been illustrated. The specimen number is taken from Fossilworks' website, though the Museum d'Histoire naturelle de Boulogne-sur-Mer (MHNB) closed in 2003 and transferred its collections to the Musée d'Histoire naturelle de Lille. Thus rigauxi presumedly has a MHNL number now instead.

Holotype of Pliosaurus suprajurensis, incomplete anterior cervical pectoral (thanks Sven Sachs) vertebra (MHNL coll.) in (left to right) ventral, left lateral, and anterior views (after Sauvage, 1879).  This may be the same species as "Cetiosaurus" rigauxi, though the latter has never been figured.

Based on the original description, rigauxi differs from sauropods such as Cetiosaurus in the short centrum (52% of height, compared to no less than 154% in Cetiosaurus), with even the short-necked Brachytrachelopan having subequal proportions at best. Furthermore, all gravisaurs have strongly opisthocoelous cervicals, whereas rigauxi's is weakly amphicoelous. The parapophyses are 55% of centrum height, while they are much smaller in sauropods (e.g. 34% in cervical 12 of Cetiosaurus). All of these features are seen in pliosaur posterior cervicals however (e.g. length/width ratio of 51-58% and parapophysis/centrum height ratio 70% in P. brachydeirus' holotype). The undivided parapophysis located on the centrum indicates Sauvage had its position in the vertebral column correct despite assigning it to the wrong group. Notably, Sauvage states the ventral surface is "cut into a peak", which suggests a median keel like that which characterizes P. brachydeirus. The latter species' holotype is from the Early Kimmeridgian, but at least one other keeled pliosaur centrum is known from the Tithonian of France- Pliosaurus suprajurensis. It's possible both rigauxi and suprajurensis are members of a long-lived P. brachydeirus, or that the French species are synonymous but distinct from P. brachydeirus. In the latter case, rigauxi would have priority over suprajurensis, but they cannot be directly compared as they're from different sections of the neck (though rigauxi is from a much larger individual, with length x height x width 85x165x185 mm vs. 50x68x75 mm in suprajurensis), and its likely neither can be anatomically distinguished from P. brachydeirus. rigauxi is not officially synonymized here though, pending verification of the keeled morphology and modern description of the specimen.

References- Sauvage, 1874. Mémoire sur les dinosauriens et les crocodiliens des terrains jurassiques de Boulogne-sur-Mer. Mémoires de la Société Géologique de France, série 2. 10(2), 1-57.
Sauvage, 1895. Les dinosauriens du terrain jurassique supérieur du Boulonnais. Bulletin de la Société Géologique de France, 3e série. 22, 465-470.
Sauvage, 1902. Note sur quelques Reptiles du Jurassique supérieur du Boulonnais. Bulletin de la Societe Academique de l‘Arrondissement de Boulogne-sur-Mer. 6, 380-398.

P? sp. (Lennier, 1887)
= "Tapinosaurus" Lennier, 1887
Late Kimmeridgian, Late Jurassic
lower Argiles d'Ecqueville Member of the Argiles d'Octeville Formation, France
- (Muséum d’Histoire naturelle du Havre; destroyed) anterior cervical centrum (70 mm) (Lennier, 1887)
(Muséum d’Histoire naturelle du Havre; destroyed) three cervical centra (80, 78, 65 mm), two cervical ribs, two partial cervical or anterior dorsal neural arches, four incomplete dorsal neural arches, six dorsal ribs (four partial, one fragmentary; 1 m) (Rabeck, 1925)
?...(Lepage coll. 15.8.31.E1) posterior cervical centrum (91 mm) (Lepage et al., 2009)
?...(Muséum du Havre IIFD358) incomplete dorsal rib (Lepage et al., 2009)
Early Kimmeridgian, Late Jurassic
Marnes de Bleville, France

(Muséum d’Histoire naturelle du Havre; destroyed) proximal dorsal rib (Lennier, 1887)

?Pliosaurus anterior cervical centrum (Muséum d’Histoire naturelle du Havre coll.) in anterior or posterior view first figured as Tapinosaurus sp., a misspelling of Tapinocephalus (after Lennier, 1887).

Comments- Lennier (1887) referred an unassociated cervical centrum and dorsal rib (both originally in the Muséum d’Histoire naturelle du Havre, but destroyed in 1944) to Tapinocephalus, then thought to be dinosaurian but now known to be a dinocephalian synapsid. This was seemingly due to their large size. The figure caption of Lennier's plate illustrating the centrum mistakenly said "Tapinosaurus sp?", clearly a misspelling of Tapinocephalus and not previously suggested to be a valid genus.
Rabeck (1925) described a specimen found in 1923 as the dinosaur "Tapinosaurus sp?", based on resemblence to Lennier's specimens, unaware that "Tapinosaurus" was not an accepted genus. This specimen (consisting of partial vertebrae and ribs) was also held at the Muséum d’Histoire naturelle du Havre and similarly destroyed in WWII. Stiegelmann (1925) provided measurements of the specimen.

Only existing photo of Rabeck's "Tapinosaurus sp." material (Muséum d’Histoire naturelle du Havre coll.), consisting of three cervical centra (left center), two cervical ribs (around the bottom centrum), neural arches and dorsal ribs (after Lepage et al., 2009).

After this, "Tapinosaurus" was seldomly mentioned. Kuhn (1939) includes Rabeck's material questionably under Omosaurus, which is treated as Saurischia indet. by Kuhn despite being stegosaurid (a replacement name for Dacentrurus). Steel (1970) realized Lennier's article was supposed to reference Tapinocephalus, but stated Rabeck's material "seemingly pertains to a large dinosaur, but is indeterminable", placing "Tapinosaurus" in Sauropoda incertae sedis.  Rabeck's specimen is not a sauropod, as it has short amphicoelous cervical centra without pleurocoels, short laterally oriented cervical ribs, dorsal neural arches lacking laminae, and single-headed dorsal ribs.  Buffetaut et al. (1991) first noticed the discrepency between the article and plate caption in Lennier's work, and identified both this centrum and Rebeck's "Tapinosaurus" as sauropterygians. Similarly, Molnar (pers comm. in Olshevsky, 1991) stated these specimens were probably plesiosaurian. Finally, Lepage et al. (2009) published detailed overview of "Tapinosaurus"' history (forming the basis of most of this entry), and redescribed the specimens as Pliosaurus sp. for Lennier's and Pliosaurus cf. macromerus for Rabeck's. They also described three new specimens from the lower Argiles d'Ecqueville, two of which might be referrable to the same individual as Rabeck's specimen as they are from the same layer and of similar size.

Holotype of Pliosaurus archiaci (MNHN 24.1), dentaries in dorsal and lateral views (after Lennier, 1870).  This may be conspecific with the "Tapinosaurus" specimens.

"Tapinosaurus" is Pliosaurus?- Unfortunately, the alpha level taxonomy of Pliosaurus is currently controversial, and most proposed distinguishing characters are cranial. The only axial character currently used to distinguish Pliosaurus species is the median ventral keel on cervical centra of P. brachydeirus. Rabeck's specimen lacks this, as do P. brachyspondylus (both current and proposed neotypes), P. funkei (paratype), P. macromerus (lectotype), P. rossicus (holotype) and P. westburyensis. Yet this morphology is plesiomorphic, also being found in e.g. Brachauchenius, Simolestes and "P." andrewsi. Pliosaurus archiaci is based on a mandible (MNHN 24.1) also discovered in the Kimmeridgian deposits of Le Havre, but cannot be compared to "Tapinosaurus". Another method would be to correlate the "Tapinosaurus" specimens stratigraphically with known Pliosaurus species. According to Lepage et al., at least Rabeck's specimen derives from the Aulacostephanus mutabilis zone of the Late Kimmeridgian. This corresponds to CAMSM J35990, a partial skeleton initially referred to a broad concept of P. macromerus (Pliosaurus without ventral cervical keels) but more recently found to be closest to P. kevani (in an analysis that did not include the P. macromerus lectotype or proposed neotype). CAMSM J35990 is similar Rabeck's specimen in being larger than most and lacking ventral cervical keels, so there may be a real large A. mutabilis zone species of Pliosaurus that is currently undiagnosed. This may correspond to the large P. portentificus, although that has been considered a nomen dubium and may belong to the more recent A. euxodus zone. Perhaps notable is that P. portentificus has the same number of symphyseal alveoli (8) as P. archiaci, whereas other species have more (>11 in P. brachydeirus, 9 in P. carpenteri, ~14-15 in P. kevani) or less (6 in P. rossicus and P. patagonicus). In any case, both P. macromerus' lectotype and proposed neotype are from more recently deposited sediments, so Lepage et al.'s assignment seems unlikely. Pending further studies, the "Tapinosaurus" material is best retained as Pliosaurus sp.. Lennier's dorsal rib is from a different locality, whose age corresponds to P. brachydeirus and P. kevani, though it is near certainly indeterminate.

References- Lennier, 1887. Études paléontologiques. Description des fossiles du Cap de la Hève. Bulletin de la Société Géologique de Normandie. 1886(12), 17-98.
Rabeck, 1925. Notes sur la découverte d'ossements de dinosaurien dans les Argiles supérieures Kimméridgiennes du Cap de la Hève (Octeville-sur-Mer). Bulletin de la Société Géologique de Normandie. 1916/1923(34), 72-74
Stiegelmann, 1925. Note additionnelle [à Notes sur la découverte d'ossements de dinosaurien dans les Argiles supérieures Kimméridgiennes du Cap de la Hève (Octeville-sur-Mer) de G. Rabeck]. Bulletin de la Société Géologique de Normandie.1916/1923(34), 75.
Kuhn, 1939. Saurischia. In Fossilium Catalogus I. Animalia. 87. 124 pp.
Steel, 1970. Part 14. Saurischia. Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Gustav Fischer Verlag, Stuttgart. 87 pp.
Buffetaut, Cuny and Le Loeuff, 1991. French dinosaurs: The best record in Europe? Modern Geology. 16, 17-42.
Olshevsky, 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.
Lepage, Buffetaut and Lepage, 2009. Qu'est-ce que Tapinosaurus? Lennier, Rabeck et les grands Sauroptérygiens du Kimméridgien supérieur de la région havraise (Normandie, France). Bulletin de la Société géologique de Normandie et des amis du Muséum du Havre. 96(1), 27-59.

Blog entry specific references- Lennier, 1870. Etudes géologiques et paléontologiques sur l'embouchure de la Seine et les Falaises de la Haute-Normandie. Imprimerie Eugène Costey, Havre. 245 pp.

Sauvage, 1879. Prodrome des Plesiosauriens et des Elasmosauriens des formations Jurassiques superieures de Boulogne-sur-Mer. Annales des Sciences Naturelles, 6 Serie. 8(13), 1-38.

Storrs, Arkhangelskii and Efimov, 2000. Mesozoic marine reptiles of Russia and other former Soviet Republics. In Benton, Shishkin, Unwin and Kurochkin (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press. 187-210.

Tuesday, August 25, 2015

Another Triassic tooth, Paleosaurus fraserianus

Today is the last day of my three week vacation, during which I got a lot accomplished.  This included adding four ex-saurischians to the Theropod Database, which will each get their own post this week before I upload this month's updates to the website.  The first of these ex-saurischians is one whose identity was solved a century ago, but continues to be misunderstood by dinosaur workers.

Clepsysaurus? fraserianus (Cope, 1878a) Hay, 1930
= Paleosaurus fraserianus Cope, 1878a (as Palaeosaurus fraserianus)
= Thecodontosaurus fraserianus (Cope, 1878a) Hay, 1902
= Palaeosauriscus fraserianus (Cope, 1878a) Kuhn, 1965
Norian, Late Triassic
New Oxford Formation, Pennsylvania, US
- (AMNH 1861) tooth (20x6.5x? mm)

Holotype of Paleosaurus fraserianus (AMNH 1861) at center with section (after Huene, 1921) compared to from left to right- holotype of Paleosaurus cylindrodon (BRSMG Ca7449/4) with section (after Huxley, 1870 and Huene, 1908 respectively); right fourth premaxillary tooth of Nicrosaurus kapffi (SMNS 13078) with sections (after Hungerbuhler, 2000); eighth and ninth dentary teeth of Thecodontosaurus antiquus neotype (BRSMG Ca4529/2) (after Galton, 2007); third dentary tooth of Anchisaurus polyzelus (YPM 209) with drawing (after Fedak and Galton, 2007).

Comments- Cope (1878a) described this tooth (which was first presented the year prior) as a new species of Palaeosaurus, at the time a common misspelling of Paleosaurus. Olshevsky (2000) was the first to correct the genus' spelling in this binomial. Note there is a valid genus Palaeosaurus (Geoffroy Sant-Hillaire, 1836; which is currently a junior synonym of the teleosaurid Steneosaurus) however, which caused Kuhn (1965) to incorrectly think Paleosaurus was preoccupied since its spelling is so similar. Thus he referred all Paleosaurus species to his new genus Palaeosauriscus, but this is unnecessary according to the ICZN. Paleosaurus itself is based on P. cylindrodon, an archosauriform tooth of uncertain affinities from the Norian of England which differs from fraserianus in having elongate and oblique serrations, being less recurved, and having a more tapered distal edge in section (far left in figure above).

fraserianus a dinosaur? Nopsca (1901) was the first to assign the species explicitly to Dinosauria or Theropoda, assigning it to a subfamily Anchisauridae [sic] within Megalosauridae, but his anchisaurids consisted largely of basal sauropodomorphs and Triassic carnivorous archosauriform teeth. Hay (1902) had a similar concept for Anchisauridae within his Theropoda, similarly placing fraserianus there though assigning it to Thecodontosaurus, as he synonymized the genus with Paleosaurus. Note Colbert and Chaffee (1941) wrongly cited Cope (1878b) as using the combination Thecodontosaurus fraserianus, but that work only uses Thecodontosaurus for T. gibbidens. Hay (1930) retained fraserianus in Anchisauridae and Theropoda, but now placed it in the genus Clepsysaurus (a parasuchian), perhaps based on the similarity noted by Huene (see below). Steel (1970) referred it to his theropodan Ornithosuchidae, which besides Ornithosuchus contained Teratosaurus, Triassic carnivorous archosauriform teeth, and basal sauropodomorph remains incorrectly associated with the latter. The most confusing generic assignment has been that of Olshevsky (1991, 2000), who made fraserianus a junior synonym of Anchisaurus polyzelus, which is from the much later (Pliensbachian) Portland Formation of Connecticut. fraserianus is quite unlike sauropodomorph teeth (including Thecodontosaurus and Anchisaurus; pictured at right in figure above) in being highly recurved, with an unconstricted base, little labiolingual compression, and small serrations which are perpendicular to the tooth axis. The connection was maintained through history largely via ignorance of fraserianus' actual morphology in addition to continued confusion of Paleosaurus with Thecodontosaurus and Efraasia.

fraserianus a parasuchian? Lesley (1889) may be the first author to suggest fraserianus is parasuchian, albeit without evidence. Huene (1921) has been the only author to illustrate fraserianus, and briefly described the specimen as well. Huene convincingly illustrated the similarity with other New Oxford parasuchian teeth. He suggested fraserianus was synonymous with Clepsysaurus? veatleianus and/or Rutiodon carolinensis from the same formation. Colbert and Chaffee (1941) made fraserianus a junior synonym of Clepsysaurus pennsylvanicus, based on geography. Of Norian archosauriforms which have recurved teeth with small serrations, only some proterochampsids and phytosaurid parasuchians are reported to have reduced labiolingual compression as in fraserianus (80% of FABL). While proterochampsid teeth remain largely undescribed, they are exclusively South American, so are an unlikely identification for fraserianus. Indeed, phytosaurid material is common in the New Oxford Formation, with Rutiodon carolinensis the only currently recognized valid taxon. It's therefore possible Huene was correct and that fraserianus is synonymous with Rutiodon, but the most recent review also suggested the presence of a larger, poorly characterized form (e.g. SMP VP-36; YPM-PU 11544). The tooth of fraserianus is much smaller than these latter elements, but could be ontogenetically young as well. Unfortunately, heterodonty is so great among phytosaurid dentitions, few of which have been described in detail, that it is not currently possible to assign isolated teeth to particular genera or species. Thus fraserianus remains Phytosauridae indet., and is here placed questionably in Clepsysaurus as that is the only phytosaurid genus prior authors have referred the species to.  Based on the variation in Nicrosaurus, fraserianus may be based on a premaxillary or anterior maxillary tooth.

References- Huxley, 1870. On the classification of the Dinosauria, with observations on the Dinosauria of the Trias. Quarterly Journal of the Geological Society of London. 26, 32-51.

Cope, 1878a. On some saurians found in the Triassic of Pennsylvania, by C. M. Wheatley. Proceedings of the American Philosophical Society. 17(100), 231-232.

Cope, 1878b. Triassic saurians from Pennsylvania. The American Naturalist. 12, 58.

Lesley, 1889. A Dictionary of the Fossils of Pennsylvania and Neighboring States Named in the Reports and Catalogues of the Survey. Volume 2. The Board of Commissioners for the Geological Survey, Harrisburg. 914 pp.

Nopcsa, 1901. A dinosaurusok atnezete es szarmazasa. Földtani Közlöny. 31, 193-224.

Hay, 1902. Bibliography and catalogue of the fossil Vertebrata of North America. United States Geological Survey Bulletin. 179, 868 pp.

Huene, 1908. Die Dinosaurier der europäischen Triasformation mit Berücksichtiging der aussereuropäischen Vorkommnisse. Geologische und Paläontologische Abhandlungen Supplement-Band. 1, 419 pp.

Huene, 1921. Reptilian and stegocephalian remains from the Triassic of Pennsylvania in the Cope collection. Bulletin American Museum of Natural History. 44(19), 561-574.

Hay, 1930. Second Bibliography and Catalogue of the Fossil Vertebrata of North America. Carnegie Institution of Washington. 390(II), 1-1074.

Colbert and Chaffee, 1941. The type of Clepsysaurus pennsylvanicus and its bearing upon the genus Rutiodon.

Kuhn, 1965. Saurischia (Supplementum 1). In Fossilium Catalogus 1. Animalia. 109, 94 pp.

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

Hungerbuhler, 2000. Heterodonty in the European phytosaur Nicrosaurus kapffi and its implications for the taxonomic utility and functional morphology of phytosaur dentitions. Journal of Vertebrate Paleontology. 20(1), 31-48.

Olshevsky, 2000. An annotated checklist of dinosaur species by continent. Mesozoic Meanderings. 3, 1-157.

Fedak and Galton, 2007. New information on the braincase and skull of Anchisaurus polyzelus (Lower Jurassic, Connecticut, USA; Saurischia: Sauropodomorpha): Implications for sauropodomorph systematics. In Barrett and Batten (eds.). Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. Special Papers in Palaeontology. 77, 245-260.

Galton, 2007. Notes on the remains of archosaurian reptiles, mostly basal sauropodomorph dinosaurs, from the 1834 fissure fill (Rhaetian, Upper Triassic) at Clifton in Bristol, southwest England. Revue de Paléobiologie. 26(2), 505-591.