Rachitrema is an ichthyosaur of course

Along with Actiosaurus, Sauvage described another supposed dinosaur now thought to be an ichthyosaur.

Rachitrema Sauvage, 1883
R. pellati Sauvage, 1883
Rhaetian, Late Triassic
limestone at Conches-les-Mines, Autun, Saône-et-Loire, France
Lectotype (proposed)- (Pellat coll.) (~6.5 m) posterior dorsal neural arch (140 mm tall)
Paratypes- ?(Pellat coll.) scapula (220 mm)
(Pellat coll.) (Amniota incertae sedis) skull fragment, three dorsal rib fragments, proximal ?humerus, distal ?ilium or ?fibula, partial ?pelvic element

Rachitrema pellati type neural arch in posterior (4b), right lateral (4) and anterior (4a) views.  After Sauvage (1883).

Comments- Sauvage (1883) described this material as a new taxon of dinosaur, though an oddly primitive one which he does not favorably compare to any other species. The specimen Sauvage based the name on is a neural arch he assigned to the caudal series, while he referred additional bones ("undoubtedly to the same animal") identified as a braincase fragment, at least three dorsal rib fragments, a scapula, proximal humerus, proximal radius and distal pubis. He notes the neural arch was unfused to the centrum, citing this as a primitive character. The structure of the prezygapophyses and ligament pits are compared to Actinodon (now recognized as a junior synonym of the temnospondyl Onchiodon), while the cranial fragment, scapula and humerus are compared to crocodilians and the latter two at least are said to differ from Megalosaurus and Cetiosaurus. Boulenger (1883) attempted to respell the name Racheotrema without comment. It has also sometimes been misspelled Rhachitrema, starting with Boettger (1884). Zittel (1890) stated it was a possible zanclodontid theropod (though insufficiently characterized), though he later (1895) stated it was a megalosaurid close to Zanclodon instead. Pocta (1905) also placed it in Megalosauridae, while Simroth (1907) placed it in Zanclodontidae. Nopsca (1901) assigned it to Anchisauridae, which was thought to be a theropod family at the time. Huene (1902) identified Rachitrema's type neural arch as that of an ichthyosaur and synonymized the genus with Shastasaurus without comment. Sauvage (1903) agreed Rachitrema was an ichthyosaur and synonymized it with the contemporaneous Ichthyosaurus? rheticus, since he believed that species to be more similar to Shastasaurus than the also contemporaneous I? carinatus. He regarded the scapula to be more similar to Toretocnemus (as Leptocheirus) than Ichthyosaurus, and the reidentified distal ilium (previously thought to be a distal radius) to be like Toretocnemus and Shastasaurus. The supposed proximal humerus and distal pubis could not be compared well. Merriam (1908) kept Rachitrema as a synonym of Ichthyosaurus? rheticus and believed the type neural arch was more primitive than Jurassic plesiosaurs. Huene (1908) synonymized it with Ichthyosaurus, crediting his 1902 paper despite the fact that work had it synonymized with Shastasaurus. Huene (1922) now listed Rachitrema as a junior synonym of Leptopterygius? rheticus (Leptopterygius has since been replaced by Leptonectes), though referring to not only the type neural arch but also a "supposed ischium". He later (1951) listed Rachitrema as a possible synonym of Merriamia (now a synonym of Toretocnemus), as did Romer (1976). Bardet and Cuny (1993) accepted some of the material as possibly ichthyosaurian, but assigned the rest to Reptilia indet.. McGowan and Motani (2003) consider Rachitrema to be probably dinosaurian without justification.

When evaluating Rachitrema, it should first be noted that no neural arches have been described for rheticus, so the two taxa cannot be shown to be synonyms. Thus rheticus can be ignored in the following discussion. In addition, there is no evidence the material described as Rachitrema belongs to one individual or taxon. It was all found isolated and by two different collectors. The neural arch is here proposed to be the lectotype, as the genus name refers to it and Sauvage states "The remarkable characters present in this neural arch make us think they indicate a dinosaurian of unknown type which we will indicate under the name Rachitrema." The neural arch is not dinosaurian, as it differs from dinosaur presacrals and proximal caudals in lacking transverse processes and having reduced zygapophyses which are placed near the midline. Nor is it from a distal caudal, which have reduced neural spines. The neural arch does strongly resemble ichthyosaurs in these characters however, so Huene's identification was correct. Within Ichthyopterygia, Rachitrema is outside Neoichthyosauria based on its divided postzygapophyses (Maisch and Matzke, 2000), as expected for a Triassic taxon. This indicates it is not synonymous with Ichthyosaurus or Leptonectes, though it still may be Shastosaurus or Toretocnemus. It is probably a member of Longipinnati, as no more basal ichthyosaurs are known from the Late Jurassic. Pending further study, Rachitrema is considered Ichthyopterygia incertae sedis. The scapula has a short contact surface for the coracoid (~23% of scapular length), as in Cymbospondylus and non-longipinnatin taxa. The moderately sized anterior blade expansion is similar to Cymbospondylus, Shastasaurus and Shonisaurus, unlike the large flange of non-longipinnatins or the parvipelvians, Besanosaurus, Californosaurus, Mikadocephalus and Callawayia. Similarly, the low posterior blade expansion is unlike non-longipinnatins and neoichthyosaurs. The referred scapula is thus from a longipinnatin ichthyosaur that seems most similar to Cymbospondylus. The supposed distal ilium could indeed belong to an ichthyosaur like Cymbospondylus, Toretocnemus or Californosaurus, or it could be a partial long bone shaft of a non-ichthyosaur (e.g. choristodere or dinosaur distal fibula) as originally described. The other paratype fragments deserve detailed comparison to a wide variety of Triassic taxa, though the supposed humerus is certainly not an ichthyosaur humerus based on its elongation and the supposed distal pubis (which could also be a choristodere ventral ilium for instance) resembles parvipelvian pubes in rough shape but not Triassic ichthyosaurs.

References- Boulenger, 1883. Reptilia and Batrachia. in Rye (ed.). The Zoological Record for 1883. Record of Zoological Literature. 20, 24 pp.

Sauvage, 1883. Recherches sur les reptiles trouves dans l'etage Rhetien des environs d'Autun. Annales des Sciences Geologiques. 14(6, Article 3), 1-44.

Boettger, 1884. Bericht über die Leistungen in der Herpetologie während des Jahres 1883. Archiv Fur Naturgeschichte. 50(2), 379-434.

Zittel, 1890. Handbuch der Palaeontologie. Volume III. Vertebrata (Pisces, Amphibia, Reptilia, Aves).

Zittel, 1895. Grundzüge der Palaeontologie (Palaeozoologie). 971 pp.

Nopcsa, 1901. Synopsis und Abstammung der Dinosaurier. Földtani Közlöny. 31, 247-288.

Huene, 1902. Übersicht über die Reptilien der Trias [Review of the Reptilia of the Triassic]. Geologische und Paläontologische Abhandlungen (Neue Serie). Gustav Fischer Verlag, Jena. 6, 1-84.

Sauvage, 1903. Note sur les reptiles de letage Rhetien des environs d'Autun. Bulletin Societe d'Histoire Naturelle d'Autun (France). 16, 309-318.

Pocta, 1905. Rukovet Palaeozoologie. II. Cast: Vertebrata. 310 pp.

Simroth, 1907. Die Pendulationstheorie. Leipzig Konrad Grethlein's Verlag. 564 pp.

Huene, 1908. Die Dinosaurier der europäischen Triasformation mit Berücksichtiging der aussereuropäischen Vorkommnisse [The dinosaurs of the European Triassic Formation, with consideration of non-European occurrences]. Geologische und Paläontologische Abhandlungen Supplement-Band. 1, 419 pp.

Merriam, 1908. Triassic Ichthyosauria: With special reference to the American forms. 196 pp.

Huene, 1922. Die Ichthyosaurier des Lias und ihre Zusammenhänge. Jahresversammlung der palaeontologischen Gesellschaft. Verlag Bornträger, Berlin. 114 pp.

Huene, 1951. Eine neue Ichthyosaurier-Gattung der mitteleren Trias. Neues Jahrbuch fur Geologie und Palaontologie, Abhandlungen. 94, 80-92.

Romer, 1976. Osteology of the Reptiles. University of Chicago Press. 772 pp.

Bardet and Cuny, 1993. Triassic reptile faunas from France. Paleontologia Lombarda. 2, 9-17.

McGowan and Motani, 2003. Handbook of Paleoherpetology: Ichthyopterygia, Part 8. 175 pp.

Actiosaurus is a choristodere not an ichthyosaur

Ah Actiosaurus, an obscure genus if there ever was one.  Not only has no one bothered to examine the material in over a century, it hasn't even been mentioned in the literature since 1908 except in Olshevsky (2000) as a non-dinosaur.  Its Wikipedia entry gives it the wrong year of description, wrong citation, wrong period, wrong species name, wrong date for the wrong species name, and wrong identification.  So let's find out the correct information about this taxon...

Actiosaurus Sauvage, 1883
A. gaudryi Sauvage, 1883
Rhaetian, Late Triassic
limestone at Conches-les-Mines, Autun, Saône-et-Loire, France
Lectotype (proposed)- (Pellat coll.) proximal humerus (~105 mm)
Paratypes- (Pellat coll.) (Amniota incertae sedis) centrum (65 mm), humerus (90 mm), proximal ?humerus

Actiosaurus proximal humerus ("femur") in side (1a) and anterior (1) views.  Amniote humerus originally referred to Actiosaurus in anterior view (2). Pachystropheus proximal humerus in side (3a) and anterior (3) views. Figures 1 and 2 after Sauvage (1883), figure 3 after Storrs et al. (1996).

Comments- Sauvage described this as a probable dinosaur most similar to Palaeosaurus (based on Thecodontosaurus material) within the Megalosauridae (in which he placed all theropods), though differing in the more projecting femoral head, more poorly developed greater trochanter, and marked tuberosity on the proximal humerus. Sauvage based the taxon on two supposed proximal femora of different sizes, a humerus "found with them" and a more questionably referred centrum supposedly from the dorsal series. While the femoral morphology suggested something intermediate between crocodiles and lizards, Sauvage believed the vertebral centrum would indicate Actiosaurus was dinosaurian if properly referred (due to the oblique articular surfaces). The species name was misspelled A. gaudrii by Boulenger (1883). Later authors often placed it in whichever theropod family they included Paleosaurus in- Mayer (1886) in Amphisauridae, and Simroth (1907) and Zittel (1890) in Zanclodontidae. Zittel was provisional in his assignment though and stated Actiosaurus was insufficiently characterized. Huene (1902) listed it provisionally under Lycosauria (containing gorgonopsids and theriocephalans), and Werner (1906) listed it under Thecodontia. Sauvage (1903) disagreed with Huene's identification, noting that while resemblences between Actiosaurus and some "anomodonts" such as Deuterosaurus (now recognized as a dinocephalan) existed, the form was more similar to crocodiles. Note Stache's (1889) reference to Actiosaurus tommasinii is a misspelling of the ophidiomorph squamate Acteosaurus. Huene (1908) referred it to Ichthyosaurus, crediting his 1902 paper despite the fact that was not his conclusion then.

The various described elements were found by two different collectors, belonged to at least two individuals based on the two sizes of "femur" and have no record of association, so could easily belong to different taxa. The bone described as the smaller proximal femur is here taken to be the type as it is illustrated, described in most detail and first, and it is the supposed femora that are said to indicate "the presence of a reptile close to Palaeosaurus." Why Actiosaurus has been referred to Ichthyosauria is not at all apparent. The limb elements are more elongate than any ichthyosaur bone, while ichthyosaur vertebrae are famously amphicoelous unlike the weakly biconvex centrum referred to Actiosaurus. The limb elements are also more elongate with better developed articular surfaces than sauropterygians. Compared to contemporaneous dinosaurs, the humerus has a much smaller and proximally located deltopectoral crest and more greatly expanded distal end, while the supposed femur would differ in having a basically proximally projecting elongated and flattened head. However, the "femur" is extremely similar to the humerus of the choristodere Pachystropheus, which is common in Rhaetian beds of England. Points of similarity include the head structure just noted, as well as the deltopectoral crest (greater trochanter of Sauvage) which is an oval knob placed in the center of the anterior face, at the same distance from the head. It is also within the size range of Pachystropheus specimens (greatest transverse width 25 mm compared to 13-35 mm). Interestingly, Actiosaurus has priority over Pachystropheus (named by Huene in 1935). However, Pachystropheus' proximal humeri exhibit so much individual variation and are not distinct from other choristoderes (e.g. Irenosaurus). Thus Actiosaurus is best left as Choristodera indet.. Whether the additional proximal "femur" is also a choristodere humerus is unknown, as it is not illustrated and only stated to be larger (though with oddly different bredth vs. depth proportions given). The element described as a humerus seems to be correctly identified, but it differs from Pachystropheus in being more abruptly expanded proximally and straighter, with a more proximally placed deltopectoral crest. Its affinities require a broader look at amniote humeri. The centrum is not from a choristodere, as it is weakly biconvex to amphiplatyan, taller than long, has oblique articular faces and a longitudinal ventral groove (as in Pachystropheus caudals, but those further differ in being fused to their neural arches at a much smaller size than the Actiosaurus centrum). Among dinosaurs, only caudal vertebrae usually have ventral grooves (common in theropods at least), though only cervicals usually have oblique faces. Plateosaurus ingens does have oblique faces on its caudal centra though, making it a potential candicate for the Actiosaurus centrum. Yet with such a brief description and no illustration, further comparison to other amniotes is warranted before any judgement is made.

References- Boulenger, 1883. Reptilia and Batrachia. in Rye (ed.). The Zoological Record for 1883. Record of Zoological Literature. 20, 24 pp.

Sauvage, 1883. Recherches sur les reptiles trouves dans l'etage Rhetien des environs d'Autun. Annales des Sciences Geologiques. 14(6, Article 3), 1-44.

Mayer, 1886. Herausgegeben von der Zoologischen Station zu Neapel. IV. Abtheilung: Tunicata, Vertebrata. 413 pp.

Stache, 1889. Die Liburnische Stufe und deren Grenzhorizonte, eine Studie uber die Schichtenfolgen der cretacisch-eocanen oder protocanen Landbildungs-Periode im Bereich der Küstenländer von Oesterreich-Ungarn mit einer einleitenden Uebersicht der geologischen Verhältnisse dieses Gebietes. Abhandlungen der geologischen Bundesanstalt. 13, 170 pp.

Zittel, 1890. Handbuch der Palaeontologie. Volume III. Vertebrata (Pisces, Amphibia, Reptilia, Aves).

Huene, 1902. Übersicht über die Reptilien der Trias [Review of the Reptilia of the Triassic]. Geologische und Paläontologische Abhandlungen (Neue Serie). Gustav Fischer Verlag, Jena. 6, 1-84.

Sauvage, 1903. Note sur les reptiles de letage Rhetien des environs d'Autun. Bulletin Societe d'Histoire Naturelle d'Autun (France). 16, 309-318.

Werner, 1906. Reptilia und Amphibia fur 1903. Archiv fur Naturgeschichte. 1-70.

Simroth, 1907. Die Pendulationstheorie. Leipzig Konrad Grethlein's Verlag. 564 pp.

Huene, 1908. Die Dinosaurier der europäischen Triasformation mit Berücksichtiging der aussereuropäischen Vorkommnisse [The dinosaurs of the European Triassic Formation, with consideration of non-European occurrences]. Geologische und Paläontologische Abhandlungen Supplement-Band. 1, 419 pp.

The third Dinosaurus

Here's a quickie before I leave for work.  Everyone knows about the Dinosaurus that's a synapsid, and the "Dinosaurus" that's a sauropodomorph.  But did you know there's a third "Dinosaurus"?

"Dinosaurus" Lessem and Glut, 1993


Comments- Lessem and Glut (1993) included an entry for a genus named Dinosaurus in their popular book "The Dinosaur Society's Dinosaur Encyclopedia". This was supposed to be a theropod from the Late Cretaceous of India known from fragmentary ribs and a caudal vertebra. However, personal communication with Glut (2000) indicates that the entry was an error by Lessem and does not reflect any real specimen.

Dinosaurus is the name of two other proposed genera though. Dinosaurus murchisoni (Fischer, 1845) Fischer, 1847 is a junior synonym of the anteosaurid synapsid Brithopus priscus. Contra some sources, Seeley (1895) did not try to name another genus Dinosaurus, but rather described a femur he referred to Dinosaurus that has been subsequently referred to the dinocephalan synapsid Phreatosuchus qualeni. "Dinosaurus gresslyi" was named without a description by Rutimeyer (1856a), so was a nomen nudum. It needed to be renamed due to Fischer's genus anyway, so was officially described as Gresslyosaurus ingens by Rutimeyer later that year (1856b). As "Dinosaurus gresslyi" was invalid, Olshevsky's (2000) claim the species name should still be gresslyi is incorrect. The species is a plateosaurid and is often placed in Plateosaurus itself, though this is a matter of personal preference.

References- Fischer, 1845. Beitrag zur naeheren Bestimmung des von Hrn. Wangenheim von Qualen abgebildeten und beschriebenen Saurier-Schaedels. Bulletin de la Societe Imperiale des Naturalistes de Moscou. 18, 540-543.

Fischer, 1847. Bemerkungen uber das Schadel-Fragment, welches Herr Major Wangenheim von Qualen in dem West-Ural entdeckt und der Gesellschaft zur Beurteilung vorgelegt hat. Bulletin de la Societe Imperiale des Naturalistes de Moscou. 20, 263-267.

Rutimeyer, 1856a. Dinosaurus gresslyi. Bibliotheque Universelle des Sciences Belles-Lettres et Arts, Geneve. September, 53.

Rutimeyer, 1856b. Reptilienknochen aus dem Keuper. Allgemeine Schweizerische Gesellschaft fur de Gesammten Naturwissenschaften. 41, 62-64.

Seeley, 1895. Researches on the structure, organization and classification of the fossil Reptilia. Part IX, section 1. On the Therosuchia. Philosophical Transactions of the Royal Society of London, series B. 185(21), 987-1018.

Lessem and Glut, 1993. The Dinosaur Society's Dinosaur Encyclopedia. New York: Random House.

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

Arctosaurus the poposaurid

Continuing our treck through ex-theropods is the mysterious vertebra named Arctosaurus.

Arctosaurus Adams, 1875
A. osborni Adams, 1875
Late Triassic
Heiberg Formation, Nunavut, Canada
Holotype- (NMI 62 1971) incomplete third cervical vertebra (33 mm)

Diagnosis- (suggested) differs from Ctenosauriscus in low cervical neural spine; differs from Lotosaurus in offset centrum faces.

Arctosaurus osborni holotype NMI 62 1971, third cervical vertebra in A. anterior, B. left lateral, C. posterior, D. ventral and E. dorsal views.  Scale = 25 mm. (after Galton and Cluver, 1976)

Comments- This was discovered in 1853 and though originally identified as a Teleosaurus vertebra, was described by Adams (1875) as a new reptilian genus more similar to lizards than crocodiles. Non-dinosaurian identifications include Huene's (1902) suggestion it is a testudine. This was based on comparison to his new genus Chelyzoon, which he believed to be a turtle but has since been synonymized with the archosauromorph Tanystrophaeus. Thus a relationship with turtles can be discounted. Baird (in Russell, 1984) suggested it was a trilophosaurid. This needs to be seriously considered, as trilophosaurs have epipophyses and spinopostzygapophyseal laminae. However, they differ in having platycoelous to procoelous centra (in Spinosuchus and Trilophosaurus) which lack a posterior centrodiapophyseal lamina and have larger epipophyses. Furthermore, Arctosaurus has closely situated postzygapophyses which lack the broad horizontal transpostzygapophyseal laminae characteristic of Trilophosaurus and Spinosuchus. The rhynchosaur Mesosuchus also has epipophyses, but similarly differs in lacking posterior centrodiapophyseal laminae as well as having prominent posterodorsally placed diapophyses.

Arctosaurus a dinosaur? Lydekker (1890) placed it in Theropoda fam. indet., stating it was probably related to Anchisaurus (which he viewed as a theropod). Indeed, authors such as Lydekker (1889) and Marsh (1895) placed it in Anchisauridae. A relationship to basal sauropodomorphs remained the consensus until Galton and Cluver (1976) placed it in Theropoda instead due to the short and high proportions and supposed pleurocoel. Additional authors who have placed Arctosaurus in Theropoda include Steel (1970), Welles (1984; as a nomen dubium) and Weishampel (1990). The elongate centrum with offset articular surfaces is like dinosauriforms, and the presence of epipophyses is like dinosaurs. Within Dinosauria, the lack of a pleurocoel excludes it from Avepoda, the relatively short centrum excludes it from Sauropodomorpha (even compared to Panphagia and Pantydraco), and the shortness of the epipophyses exclude it from Theropoda. It is unlike basal ornithischians like Eocursor and Heterodontosaurus in the anteroventral placement of the diapophysis and thus probably parapophysis, and in the well developed posterior centrodiapophyseal lamina which marks a lateral fossa (pleurocoel of Galton and Cluver).

Arctosaurus an archosauriform? The specimen was most recently reviewed by Nesbitt et al. (2007), who placed it as Archosauriformes indet.. Ignoring dinosaurs, epipophyses are only known in some ornithosuchians (e.g. Revueltosaurus, Lotosaurus), while the elongate centrum with offset sides resembles those of Xilousuchus, some poposaurids and crocodylomorphs. Thus Poposauroidea is the most likely candidate. It is more similar to poposaurids than basal poposauroids (Yarasuchus, Qianosuchus) in the well developed posterior centrodiapophyseal lamina. Within poposaurids, Arctosaurus is more similar to Lotosaurus, Ctenosauriscus and Poposaurus than Arizonasaurus, Sillosuchus, Effigia and Shuvosaurus in having a shorter centrum. As in Arizonasaurus but unlike Sillosuchus, Effigia and Shuvosaurus, the centrum is transversely compressed. It is further similar to Arizonasaurus and Lotosaurus, but unlike Poposaurus, Sillosuchus, Effigia and Shuvosaurus in lacking a pleurocoel. Like Lotosaurus and apparently Ctenosauriscus, but unlike Arizonasaurus, Poposaurus, Effigia and Shuvosaurus, Arctosaurus has postaxial epipophyses. Thus it seems most similar to Lotosaurus and Ctenosauriscus. As it differs from both taxa, it is not indeterminate, contra Welles and Nesbitt et al..

References- Adams, 1875. On a fossil saurian vertebra, Arctosaurus osborni, from the Arctic regions. Proceedings of the Royal Ireland Academy. 2, 177-179.

Lydekker, 1889. Notes on new and other dinosaurian remains. Geological Magazine, decade 3. 6(8), 352-356.

Lydekker, 1890. Catalogue of the Fossil Reptilia and Amphibia in the British Museum (Natural History), Cromwell Road, S.W., Part IV. Containing the orders Anomodontia, Ecaudata, Caudata and Labyrinthodontia; and supplement. British Museum of Natural History, London. 295 pp.

Marsh, 1895. On the affinities and classification of the dinosaurian reptiles. American Journal of Science. 50(300), 483-498.

Huene, 1902. Übersicht über die Reptilien der Trias [Review of the Reptilia of the Triassic]. Geologische und Paläontologische Abhandlungen (Neue Serie). Gustav Fischer Verlag, Jena. 6, 1-84.

Steel, 1970. Part 14. Saurischia. Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Gustav Fischer Verlag, Stuttgart. 1-87.

Galton and Cluver, 1976. Anchisaurus capensis (Broom) and a revision of the Anchisauridae. Annals of the South American Museum. 69, 121-159.

Russell, 1984. A check list of the families and genera of North American dinosaurs. Syllogeus Series No. 53. National Museums of Canada.

Welles, 1984. Dilophosaurus wetherilli (Dinosauria, Theropoda), osteology and comparisons. Palaeontographica. Beiträge zur Naturgeschichte der Vorzeit. Abteilung A: Paläozoologie, Stratigraphie. 185, 85-180.

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

Nesbitt, Irmis and Parker, 2007. A critical re-evaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology. 5(2), 209-243.

Bathygnathus the sphenacodontid

If you couldn't tell from that last post, I'm working on the ex-theropod section of my website.  These things go at a pretty quick pace, so you might expect a large number of blog posts this month. 

Bathygnathus Leidy, 1853
B. borealis Leidy, 1853
Kungurian, Early Permian
Red Beds, Prince Edward Island, Canada
Holotype- (ANSP 9524) partial premaxilla, incomplete maxilla, anterior nasal, seven teeth

Bathygnathus snout (bottom) compared to Dimetrodon skull (top), taken from a Wikipedia image by Bogdanov.

Comments- The holotype was discovered in 1845 and originally briefly described by Leidy (1853) as the mandible of a reptile, and later (1854, 1855) described in more depth as a lizard ("lacertian"). Cope (1868) suggested it was related to Dryptosaurus and provisionally placed it in his Goniopoda (=Theropoda) in 1870. Huene (1902) referred it to his theropod family Zanclodontidae, believing it might be synonymous with Teratosaurus. It was also commonly referred to the Amphisauridae (e.g. Marsh, 1882), and the Anchisauridae which replaced it (e.g. Marsh, 1885) when these were thought to be theropod groups. Owen (1876) correctly identified the specimen as an upper jaw and suggested a relationship to theriodonts (and Lycosaurus in particular) based on the presence of a canine tooth, reduced incisor and other characters. This was not confirmed until Case (1905) and Huene (1905) independently reidentified Bathygnathus as a "pelycosaurian" synapsid, Case believing it to be either Dimetrodon or Naosaurus (a junior synonym of Edaphosaurus that was mistakenly given a Dimetrodon skull). It was referred to Sphenacodontidae by Romer and Price (1940), and Sphenacodontinae in particular by Reisz (1986). However, Reisz et al. (1992) determined that the other subfamilies are invalid, as Haptodus is basal to sphenacodontids+therapsids, while Secodontosaurus is deeply nested within Sphenacodontidae. Using their analysis, Bathygnathus is a sphenacodontoid based on the lacrimal not contacting the naris, strongly convex ventral maxillary edge, canines more than twice as long as other maxillary teeth, less than four maxillary pre-canines, and serrated teeth. Within Sphenacodontidae, it seems to be closer to Dimetrodon and Secodontosaurus than Sphenacodon and Ctenospondylus based on the elongate maxillonasal suture.

References- Leidy, 1853. [Remarks on Bathygnathus borealis]. Proceedings of the Academy of Natural Sciences of Philadelphia. 6, 404.

Leidy, 1854. On Bathygnathus borealis, an extinct saurian of the New Red Sandstone of Prince Edward Island. Proceedings of the Academy of Natural Sciences of Philadelphia, second series. 2(4), 327-330.

Leidy, 1855. On Bathygnathus borealis, an extinct saurian of the New Red Sandstone of Prince Edward's Island. American Journal of Science, series 2. 19, 444-446.

Cope, 1868. Remarks on extinct reptiles which approach birds. Proceedings of the Academy of Natural Sciences of Philadelphia. 19, 234-235

Cope, 1870. Synopsis of the extinct Batrachia, Reptilia and Aves of North America. Transactions of the American Philosophical Society. 14, 1-252.

Owen, 1876. Evidences of theriodonts in Permian deposits elsewhere than in South Africa. Quarterly Journal of the Geological Society of London. 32, 352-366.

Leidy, 1881. Remarks on Bathygnathus borealis. Journal of the Academy of Natural Sciences of Philadelphia, second series. 8(4), 449.

Marsh, 1882. Classification of the Dinosauria. American Journal of Science. 23, 81-86.

Marsh, 1885. On the classification and affinities of dinosaurian reptiles. Report of the British Association for the Advancement of Science. 1884, 763.

Huene, 1902. Übersicht über die Reptilien der Trias [Review of the Reptilia of the Triassic]. Geologische und Paläontologische Abhandlungen (Neue Serie). Gustav Fischer Verlag, Jena. 6, 1-84.

Case, 1905. Bathygnathus borealis Leidy and the Permian of Prince Edward Island. Science. 22(550), 52-53.

Huene, 1905. Pelycosaurier im deutschen Muschelkalk. Neues Jahrbuch fur Minerologie, Geologie und Paleontologie. 20, 321-353.

Case, 1907. Revision of the Pelycosauria of North America. 176 pp.

Romer and Price, 1940. Review of the Pelycosauria. Geological Society of America Special Paper. 28, 538 pp.

Langston, 1963. Fossil vertebrates and the Late Palaeozoic Red Beds of Prince Edward Island. National Museum of Canada, Bulletin. 187, 36 pp.

Reisz, 1986. Pelycosauria. Handbuch der Paläoherpetologie. 17A, 102 pp.

Spalding, 1995. Bathygnathus, Canada's first "dinosaur". in Sarjeant (ed.). Vertebrate Fossils and the Evolution of Scientific Concepts. 245-254.

Priscavolucris- the bird that is a fish

One poorly known ex-dinosaur is the supposed Jurassic bird Priscavolucris.

Lonchidion Estes, 1964
?= Priscavolucris Gomez Pallerola, 1979
L? montsechi (Gomez Pallerola, 1979) new combination
= Priscavolucris montsechi Gomez Pallerola, 1979
= Lissodus palustris Gomez Pallerola, 1992
= Lissodus montsechi (Gomez Pallerola, 1979) Duffin, 2001
Late Berriasian-Early Barremian, Early Cretaceous
La Pedrera de Rubies Lithographic Limestones, Spain
Holotype- (Gomez Pallerola coll.) (~350 mm) cranium (33 mm), Meckel cartilage, ceratobranchial, teeth, neural arches, scapulocoracoids (55 mm), propterygia, metapterygia, mesopterygia, radials, pectoral fins, scales

Priscavolucris holotype with labels from Gomez Pallerola (1979).

Comments- Gomez Pallerola (1979) originally identified this as the skull, forelimbs and feathers of a Jurassic bird, naming it Priscavolucris montsechi (misspelled Priscavulucris in the figure captions). He later (1982) briefly reidentified it as a shark (cf. Selechia), which was apparent from the original photos. The skull was correctly identified, but the supposed humerus is a scapulocoracoid, the supposed radius and ulna are the basal fin elements, the wing itself is the pectoral fin with the feathers being its rays. The supposed metatarsus and pedal digits are a ceratobranchial and perhaps parts of adjacent gill arch elements (hypobranchial, epibranchial), while the supposed ribs are probably neural arches. Gomez Pallerola later (1985, 1988) referred it to the genus Lonchidion. In 1992 he described it in detail as a new species- Lissodus palustris, as Lissodus had been recently synonymized with Lonchidion. Duffin (2001) noted that while it was obviously a shark, the correct species name is still montsechi. This made the correct name for the taxon Lissodus montsechi. Rees and Underwood (2002) revised Lissodus and kept it separate from Lonchidion. They were unable to examine L. montsechi, but felt it was possibly referrable to Lonchidion and could not be distinguished from the contemporary Lonchidion microselachos using information in the literature. However, while the name they used (Lissodus palustris) would be a junior synonym of L. microselachos if the taxa were identical, the species montsechi has priority over microselachos (from Estes and Sanchiz, 1982) if they are found to be synonyms. Neither the combination Lonchidion palustris nor the more correct L. montsechi have been published to my knowledge, though if correctly referred to the genus, this would be the only species known from skeletons.

References- Estes, 1964. Fossil vertebrates from the Late Cretaceous Lance Formation, eastern Wyoming. University of California Publications in Geological Sciences. 49, 1-180.

Gomez Pallerola, 1979. Un ave y otras especies fosiles nuevas de la biofacies de Santa Maria de Meya (Lerida). Boletin Geologico y Minero. 90(4), 5-18.

Estes and Sanchiz, 1982. Early Cretaceous lower vertebrates from Galve (Teurel), Spain. Journal of Vertebrate Paleontology. 2(1), 21-39.

Gomez Pallerola, 1982. Nuevas aportaciones a la ictiofauna y a la flora del Neocomiense del Montsech de Rubies (Lerida). Boletin Geologico y Minero. 93(3), 199-213.

Gomez Pallerola, 1985. Nuevos hybodontidos del Cretacico Inferior de Santa Maria de Meya (Lerida). Boletin Geologico y Minero. 96(4), 372-380.

Gomez Pallerola, 1988. Nota sobre los peces elasmobranquios de las calizas litograficas del Cretacico Inferior del Montsec (Lerida). Boletin Geologico y Minero. 99(5), 748-756.

Gomez Pallerola, 1992. Nota sobre los tiburones hybodontos de las calizas litograficas del Cretacico Inferior del Montsec (Lerida). Boletin Geologico y Minero. 103(5), 783-813.

Duffin, 2001. Synopsis of the selachian genus Lissodus Brough, 1935. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 221(2), 145-218.

Rees and Underwood, 2002. The status of the shark genus Lissodus Brough, 1935, and the position of nominal Lissodus species within the Hybodontoidea (Selachii). Journal of Vertebrate Paleontology. 22(3), 471-479.

"Carnosaurus" and "Coelurosaurus" examined

Everybody knows "Carnosaurus" and "Coelurosaurus" are two names that were mistakenly used in Huene's paper to refer to unnamed theropod remains.  But just what do the remains belong to?

"Carnosaurus" Huene, 1929
Campanian-Maastrichtian, Late Cretaceous
Allen Formation, Rio Negro, Argentina
Material- (MLP CS 1240) metatarsal IV (100 mm)
Late Cretaceous
east of Colhue Huapi Lake and north of Chico River, Chubut Group(?), Chubut, Argentina
Material- (MACN coll.) tooth (23 x 12.5 x 6 mm)
Late Coniacian, Late Cretaceous
Plottier Formation of the Rio Neuquen Group, Neuquen, Argentina
Material- ?(MLP coll.) incomplete tooth (16 x 9.5 x 6.3 mm)

Comments- Carnosaurus was listed by Huene (1929) in a faunal list for three specimens- a metapodial (MLP CS 1240) from the Allen Formation, a tooth (MACN coll.) perhaps from the Chubut group, and provisionally ("Cf. Carnosaurus") a tooth from the Plottier Formation. As Olshevsky (DML, 1999) noted, the name is probably a typographical error for Carnosauria made when translating the paper from German to Spanish. This is indicated by the fact he never attaches a name to these specimens in the description or plates, and indeed states on of the specimens is taxonomically indistinguishable from another named genus. Since "Carnosaurus" was apparently not meant as a valid name when it was published (ICZN Article 11.5), it is a nomen nudum.

"Carnosaurus" A. non-theropod metatarsal MLP CS 1240 in anterior view. B. ?abelisaurid lateral tooth from the MACN in side view, section and magnification of distal serrations. C. avepod tooth from the MLP in labial, lingual, distal and sectional views. All after Huene (1929).

MLP CS 1240 is listed as metatarsals in the faunal list, but described as a ?third metacarpal similar to Allosaurus. However, it is dissimilar to theropod metacarpals in several respects. The distal articular surface is not ginglymoid, unlike metacarpals I-III of ceratosaurs and basal tetanurines or I-II of avetheropods. There is no extensor pit dorsally unlike theropod metacarpals I and II, and ceratosaur metacarpal III. The shaft is much more robust than tetanurine metacarpal IIIs except for Torvosaurus, while the proximal end is less expanded than theropod metacarpal IIs, and the shaft is far more elongate than most theropod metacarpal Is. The form is more similar to a sauropod or ankylosaur metatarsal, both groups that are known from the Allen Formation. It is here assigned to Dinosauria indet. pending further comparisons.

The Chubut tooth is merely described under the heading "tooth of a carnivorous saurischian from the Chico River". The mesial edge is slightly concave and the distal edge slightly convex. It has fine longitudinal ridges, and 30 serrations per 5 mm which are perpendicular to the edge. Huene stated there was no difference between it and teeth he referred to Loncosaurus except for the less curved mesial edge, which he felt could be explained by a different position in the jaw. It compares well with abelisaurids in all variables except the greater serration density, so may be a member of that clade.

The Plottier tooth is smaller and Huene described it under the heading "tooth of a carnivorous saurischian", stating it was not his intention to decide whether it was a coelurosaur or carnosaur. The mesial edge is more convex than the distal edge, especially basally. There are 12.5 serrations per 5 mm, stated to be on both mesial and distal carinae. The tooth seems to be from a somewhat anterior position, as it has an asymmetrical section, with one side generally more convex except for a distally placed concavity. What are described as growth lines on the labial and lingual surfaces may be enamel wrinkles, which are apically concave in the distal half of one side. This tooth is difficult to place without further study of Gondwanan small theropod dentitions and is here assigned to Avepoda.


"Coelurosaurus" Huene, 1929
Campanian-Maastrichtian, Late Cretaceous
Allen Formation, Rio Negro, Argentina
Material- (MLP CS 1478) partial ungual (~19 mm)

Comments- Coelurosaurus was listed by Huene (1929) in a faunal list for MLP CS 1478, a partial ungual from the Allen Formation. As Olshevsky (DML, 1999) noted, the name is probably a typographical error for Coelurosauria made when translating the paper from German to Spanish. This is indicated by the fact he never attaches a name to the specimen in the description or plates (it's described under the heading "coelurosaur claw"). Since "Coelurosaurus" was apparently not meant as a valid name when it was published (ICZN Article 11.5), it is a nomen nudum.

"Coelurosaurus" ungual MLP CS 1478 in a side view; b proximal section; c side view; d distal section; e dorsal view. After Huene (1929).

The ungual consists of the distal half, which exhibits an interesting combination of features. It is highly curved and transversely compressed, suggesting it is a tetanurine manual ungual or a paravian pedal ungual (though note both Mapusaurus and alvarezsaurids differ in being straighter). The cross section at midlength is triangular (expanded ventrally), unlike the roughtly oval shape of most theropod manual unguals (e.g. Noasaurus, Fukuiraptor, Deinonychus) or the blade-like shape of Megaraptor's manual unguals and paravian sickle claws. Yet the shape is not similar to most theropod pedal unguals either, as the ventral surface is concave and the ventral transverse expansion does not flare past the sides of the ungual. Notably, the ungual is quite asymmetric, with one wall of the ventral groove projecting further ventrally. This is more prominent distally, where the groove faces more to the side than downward. The asymmetry and ventral groove are characteristic of abelisaurid pedal unguals, though these are more straight and broad. Noasaurid pedal unguals (as judged by Masiakasaurus) are also straight, are only slightly asymmetrical and are keeled ventrally. Noasaurus itself possesses a controversial ungual most recently thought to be manual which is curved and compressed like "Coelurosaurus", but is not very asymmetrical and has a ventral keel. Another possibility is that "Coelurosaurus" belongs to a bird, as many birds are comparably sized with highly curved pedal unguals. Unfortunately, comparable bird unguals (e.g. Patagopteryx, Soroavisaurus, MACN PV RN 1105) are not described in enough detail to be usefully compared. Huene considered it to be a manual ungual based on its curvature and believed it was a distinct specimen. It is here referred to Avepoda incertae sedis.

References- Huene, 1929. Los saurisquios y ornitisquios del Cretacéo Argentino. Anales del Museo de La Plata (series 3). 3, 1-196.

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