Friday, July 30, 2010

Procerosaurus and Macroscelosaurus- two Tanystropheus

Tanystropheus actually has an extensive and complicated history as a theropod, as do most of its synonyms.  We deal with two today, and note the synonymy and distribution lists in this entry don't cover remains besides those referred to "Macroscelosaurus" and Procerosaurus.  Btw, If anyone has Wild's 1973 redescription of Tanystropheus or his 1971 thesis on the same topic, I'd happily accept them. ;)

Tanystropheus Meyer, 1852
= "Macroscelosaurus" Muenster vide Meyer, 1852
= Procerosaurus Huene, 1902
T. conspicuus Meyer, 1852
= "Macroscelosaurus" Muenster vide Meyer, 1852
= Procerosaurus cruralis Huene, 1902
= "Macroscelosaurus" conspicuus (Meyer, 1852) Kuhn, 1937
Anisian, Middle Triassic
Upper Muschelkalk, Germany
- (material of "Macroscelosaurus") cervical vertebrae
Referred- (holotype of Procerosaurus cruralis) incomplete femur (~415 mm) (Huene, 1902)
Comments- In the original desciption of Tanystropheus, Meyer (1852; sometimes cited as 1847 to/or 1855) stated that Muenster thought the type cervical vertebrae were reptilian limb bones and had named them Macroscelosaurus. No species name was given, and references to "Macroscelosaurus janseni" are misspellings of the therapsid Macroscelesaurus janseni (inappropriately renamed Haughtoniscus by Kuhn, who thought the name was too similar to "Macroscelosaurus"). Kuhn (1934) used "Macroscelosaurus" as a senior synonym of Tanystropheus, citing a "Muenster, 1834" reference which subsequent authors have not been able to verify. 1830 is another year that has often been cited, though Wild (1976) stated that a search of all known works of Muenster had proved fruitless. Wild (1975, 1976) noted that since "Macroscelosaurus" was first published as a junior synonym, it is invalid and petitioned the ICZN to have it officially suppressed. This was approved by the ICZN in 1981 (Melville, 1981). Huene (e.g. 1902, 1908) listed "Macroscelosaurus" as a junior synonym of Tanystropheus in Coeluridae. Piveteau (1955) used "Macroscelosaurus" as a valid genus of tanystropheid non-synonymous with Tanystropheus, which is not possible as they are based on the same material. Similarly, Kuhn's (1935) Macroscelosauridae is an objective junior synonym of Tanystropheidae, even if "Macroscelosaurus" were the valid name.

Holotype femur of Procerosaurus cruralis in posterolateral(?) view, after Huene, 1902.
Procerosaurus cruralis was described by Huene (1902) as a eusuchian most similar to gavials, though in a rather confusing paragraph which also states the lack of a fourth trochanter seems to prove it is dinosaurian. He ironically stated some similarity could exist with Tanystropheus longicollis (now recognized as coelophysid material, in this case AMNH 2704) based on Cope's description, but examination of the specimen itself showed they weren't similar after all. In 1910, Huene stated it was similar to Saltopus and that he never regarded it as crocodilian (though he did not synonymize it with Tanystropheus yet, contra Olshevsky, 1991). Huene later (1914a) placed Procerosaurus in parentheses under Tanystropheus, perhaps indicating he had synonymized them by this time, and included both as a central coelurosaur lineage within Podokesauridae. In the same year (1914b), he described additional supposed coelurosaur femora from the slightly younger Lower Muschelkalk as being most similar to Procerosaurus. General reference works such as Zittel (1927), Romer (1956) and Kuhn (1969) also used it as a synonym of Tanystropheus, which was confirmed by Wild's (1973) osteology of the latter genus. It was synonymized with T. conspicuus by Wild, probably due to provenence. Notably, Huene's favorable comparisons to theropods used taxa which are no longer thought to be dinosaurian (Saltopus, the Lower Muschelkalk femora), while his comparison to Tanystropheus was based on a theropod femur as no appendicular elements were yet referred to that genus. The femur of Procerosaurus differs from Triassic theropods in lacking a fourth trochanter and an ectocondylar tuber. While Olshevsky stated it has sometimes been classified as an ornithischian, this seems to only be true of Procerosaurus Fritsch, 1905. This was a new genus for Iguanodon exogirarum, a Cretaceous taxon named by Fritsch in 1878 for a possible tibia. Because Fritsch's genus was preoccupied by Huene's, Olshevsky renamed it Ponerosteus in 2000.

References- Meyer, 1852. Die saurier des Muschelkalkes mit ruecksicht auf die saurier aus Buntem Sanstein und Keuper. in Zur fauna der Vorwelt, zweite Abteilung 42. 167 pp.

Fritsch, 1878. Die Reptilien und Fische der böhmischen Kreideformation. Prague. 46 pp.

Huene, 1902. Übersicht über die Reptilien der Trias [Review of the Reptilia of the Triassic]. Geologische und Paläontologische Abhandlungen. 6, 1-84.

Fritsch, 1905. Synopsis der Saurier der böhm. Kreideformation [Synopsis of the saurians of the Bohemian Cretaceous formation]. Sitzungsberichte der königlich-böhmischen Gesellschaft der Wissenschaften, II Classe. 1905(8), 1-7.

Huene, 1908. Die Dinosaurier der Europäischen Triasformation mit berücksichtigung der Ausseuropäischen vorkommnisse [The dinosaurs of the European Triassic formations with consideration of occurrences outside Europe]. Geologische und Palaeontologische Abhandlungen. Supplement 1(1), 1-419.

Huene, 1910. Ein primitiver Dinosaurier aus der mittleren Trias von Elgin. Geologische und Paläontologische Abhandlungen, 8, 315-322.

Huene, 1914a. Das natürliche System der Saurischia [The systematics of the Saurischia]. Centralblatt für Mineralogie, Geologie und Paläontologie. 1914, 154-158.

Huene, 1914b. Coelurosaurier Reste aus dem Unteren Muschelkalk. Centralblatt ftir Mineralogie, Geologie und Palaontologie. 1914, 670-672.

Zittel, 1927. Textbook of Paleontology. Macmillan Co. Limited. Vol. I, 839 pp.

Kuhn, 1934. Sauropterygia. Fossilium Catalogus I: Animalia. 69, 127 pp.

Kuhn, 1935. Rhynchocephalia (Eosuchia). Fossilium Catalogus I: Animalia. 71, 38 pp.

Kuhn, 1937. Die fossilen Reptilien. Berlin: Gebrueder Borntrager. 121 pp.

Piveteau, 1955. Traite de paleontologie. V. Amphibiens, reptiles, oiseaux. Masson, Paris. 1113 pp.

Romer, 1956. Osteology of the Reptiles. University of Chicago Press. 772 pp.

Kuhn, 1969. Proganosauria, Bolosauria, Placodontia, Araeoscelidia, Trilophosauria, Weigeltisauria, Millerosauria, Rhynchocephalia, Protorosauria. Handbuch der Palahoerpetologie. 9, 74 pp.

Wild, 1973. Die Triasfauna der Tessiner Kalkalpen. XXIII. Tanystropheus longobardicus (Bassani) (Neue Ergebnisse). Schweizerische Palaontologische Abhandlungen. 95, 1-162.

Wild, 1975. Tanystropheus H. v. Meyer, 1855 (Reptilia): Request for conservation under the plenary powers. Z.N.(S.) 2084. Bulletin of Zoological Nomenclature.32, 124-126.

Wild, 1976. Tanystropheus H. von Meyer, [1852] (Reptilia): Revised request for conservation under the plenary powers. Z.N.(S.) 2084. Bulletin of Zoological Nomenclature. 33, 124-126.

Melville, 1981. Opinion 1186. Tanystropheus H. von Meyer, [1852] (Reptilia) conserved. Bulletin of Zoological Nomenclature. 38(3), 188-190.

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

Olshevsky, 2000. An Annotated Checklist of Dinosaur Species by Continent. Mesozoic Meanderings. 3, 157 pp.

Monday, July 26, 2010

Gwyneddosaurus is Tanytrachelos- misusing nomen dubium part II

Remember that post on Agnolin et al.'s paper where they used the term nomen dubium incorrectly for Rapator?  Well, it seems Olsen has a similar issue with Gwyneddosaurus where he thinks it's clearly synonymous with a taxon he named later, and even includes a diagnosic element, but wants to make it a nomen dubium so that his more complete specimen can be the name-bearer.  Read on for more details of this ex-theropod.

Gwyneddosaurus Bock, 1945
= Tanytrachelos Olsen, 1979
G. erici Bock, 1945
= Tanytrachelos ahynis Olsen, 1979
Late Carnian, Late Triassic
Gwynedd or North Wales Member of Lockatong Formation, Pennsylvania, US

Holotype- (ANSP 15072) braincase or palatal element?, axis (8 mm), two anterior cervical neural arches (~8 mm), three posterior cervicals (7.5 mm), cervical vertebra, cervical ribs, dorsal vertebra, at least 11 dorsal ribs, gastralia, distal caudal vertebra (4 mm), three chevrons, heterotopic bone?, neural arch, scapulocoracoids, clavicles, interclavicle, radius (9 mm), proximal ulna (~9 mm), incomplete ilium (10 mm), pubis?, ischium?, femur (23 mm), proximal fibula, three phalanges (2.5, 4 mm), fragments, coelacanth fragments?
Paratype- ?(ANSP coll.) femur (36.5 mm), tibia (30 mm)
Holotype of Gwyneddosaurus erici after preparation damage with elements numbered as in Bock (1945), and taken from that paper.

Comments- Gwyneddosaurus erici was described by Bock (1945) based on a disarticulated specimen, in which he labeled the bones he identified with numbers 1-51. Bock provisionally placed the reptile in Theropoda and furthermore in Podokesauridae within Coelurosauria. This was based on the supposedly short forelimbs and gracile (perhaps hollow) postcrania, with the Triassic age probably responsible for the familial identification. The procoelous vertebrae, distally expanded presacral neural spines, and differently shaped pectoral girdle were all seen as different from Podokesaurus though. Bock also referred to "several leg bones, similar to those of our specimen" from the same locality though he did not describe these.

Gwyneddosaurus holotype elements after Huene (1948), all at same scale.  The radius and maybe ulna may be metatarsals instead.

Huene (1948) examined photographs of the material from before it was prepared by Bock, leading him to reidentify almost every element. The supposed pterygoid (16), and two other cranial elements were reidentified as a possible squamosal, basisphenoid or parasphenoid (15), and cervical vertebra (13) respectively. The supposed dorsal vertebrae (3 and 4) were reidentified as posterior cervicals, the cervical ribs (39) as chevrons, and one of the dorsal ribs (45) as an ulna. The scapula (18) and coracoid (17) were each actually a complete scapulocoracoid, and the bone Bock identified as a fused radius and ulna (22) was not mentioned but is far too short to be such. One of the ilia is actualy a probable ischium (2), and a supposed tarsal (25, perhaps meant as metatarsal) is a radius. Huene also described and figured a femur and tibia larger than the holotype which is seemingly the additional specimen noted by Bock. He felt these were possibly referrable to Gwyneddosaurus, as the femur "may be structurally identical." Huene assigned the taxon to Protorosauria based on cervicals similar to Macrocnemus and Microcnemus, holocephalous dorsal ribs, elongate and only slightly curved gastralia as in Macrocnemus and Tanystropheus, extremely short scapula with one broad and one rounded corner as in Adelosaurus, clavicle similar to Macrocnemus, ilium with small preacetabular and large postacetabular process as in Protorosaurus, and distally narrowing paratype femur as in Macrocnemus. This was followed by Camp et al. (1953) and Romer (1966), who placed it in Protorosauridae and ?Prolacertidae respectively. However, the cervical and clavicle similarities were never specified, the ilial proportions are plesiomorphic for amniotes, Adelosaurus has been more recently recognized as being of Youngina-grade, holocephalous dorsals are found in numerous taxa, gastralial morphology has not been shown to be diagnostic for tanystropheids, and the holotype femur seems not to distally narrow. Huene later (1956) placed Gwyneddosaurus in Askeptosauridae, but Askeptosaurus has shorter amphicoelous presacrals, a shorter scapula, rod-like interclavicle, no preactabular process, a longer postacetabular process, and much more robust limb elements with poorly developed features. Perhaps it was a typo.

Steel (1970) followed Bock in placing Gwyneddosaurus in Theropoda, and Welles (1984) placed it in Theropoda incertae sedis (though stating "it certainly is not even remotely related to Dilophosaurus"). While Huene never explicitly stated reasons to exclude the taxon from Theropoda, they include- procoelous cervical centra, no cervical pleurocoels, holocephalous dorsal ribs, short scapular blade, unfused clavicles, ossified interclavicle, short preacetabular process, femoral head not inturned, internal trochanter and intertrochanteric fossa present. Furthermore, the supposedly short forelimb elements were incorrectly identified, and numerous reptiles have gracile postcrania which can appear hollowed.

Olsen first (1979) stated that Gwyneddosaurus had an emargnate scapulocoracoid (though this is untrue), so could be a lizard, but was not closely related to his new tanystropheid Tanytrachelos. He did state it was nearly identical to some elements of Rhabdopelix though, and would be redescribed in the future. Olsen later (1980) thought it and Rhabdopelix could be senior synonyms of Tanytrachelos, as some elements could not be distinguished from it. As other elements differ between the taxa, Olsen thought Gwyneddosaurus should be a nomen dubium. Yet chimaerical status does not make a taxon a nomen dubium. Olsen and Baird (1986) considered Gwyneddosaurus to be a chimaera of coelacanth and possible Tanytrachelos bones. Similarly, Olsen and Flynn (1989) thought it to be a chimaera of Tanytrachelos and possible coelacanth fragments. Specifically, they stated "the large, quadranglular and keeled interclavicle characteristic of Tanytrachelos is present as are procoelous vertebrae." Instead of sinking Tanytrachelos into Gwyneddosaurus, Olsen and Flynn incorrectly consider the latter a nomen dubium because "there is significant room for doubt- certainly at the species level it is indeterminate." This statement is meaningless though as Tanytrachelos only has one recognized species, and the historical recognization of genus- and species-level characters for monospecific taxa is outdated. Indeed, when "at least part of Gwyneddosaurus more assuredly is Tanytrachelos", the former cannot be a nomen dubium. An ICZN petition would be necessary to sink Gwyneddosaurus, and since this has not been made yet it is more proper to make Gwyneddosaurus a senior synonym of Tanytrachelos. The identity of Rhabdopelix deserves further scrutiny, though it does include procoelous vertebrae. Whether the referred hindlimb is correctly referred is uncertain, as there are no proposed hindlimb apomorphies of Gwyneddosaurus, but is does seem to be tanystropheid based on the distal narrowing and is similar in size to large Tanytrachelos specimens. Spamer et al. (1995) placed Gwyneddosaurus in Tanystropheidae.

Unfortunately, comparison between the two taxa is difficult, as the pre-preparation photos of Gwyneddosaurus remain unpublished (though they are archived at the ANSP), while Tanytrachelos has only received a preliminary description. Bone 2 is not mentioned by either Bock or Huene but may be another posterior cervical. I think Huene switched bones 5 and 6 in his description, with 5 being the axis and 6 being a neural arch in dorsal view. Element 14 was believed to be an atlas or cranial bone by Bock, but is certainly too large for the former. Olsen and Baird's description of the interclavicle and comparison with Tanytrachelos suggests it is element 15, identified as a cranial bone by Bock and a para- or basisphenoid by Huene. Element 16 was identified as a possible squamosal by Huene, but does not match that element in Tanytrachelos and may be from the braincase or palate instead. Bock's supposed fused radius and ulna (22), may be an anterior dorsal rib if element 22 refers to the elongate curved bone and not the posterior cervical(?) the distal end lies over. Elements 23 and 24, identified as ischia by Bock, seem to be posterior dorsal ribs. Based on the identification as congeneric with Tanytrachelos, the two metatarsals or phalanges identified by Huene (31 and another unlabeled) are definitely the latter. The radius (25) and perhaps the ulna (45) as identified by Huene may actually be metatarsals then. A supposed (meta?)tarsal identified by Bock (27) seems more likely to be a posterior dorsal rib. Interestingly, curved triangular element 29 (called a rib by Bock), may be a heterotopic bone as found in some Tanytrachelos individuals. All of the "foot bones (32-38) which probably are toes" are anterior cervical ribs or gastralia as is at least one of the supposed manus bones (41). The other proposed manual elements (40 and 42) are very small and could be distal gastralia or fish bones. Notably, despite Olsen's statements Gwyneddosaurus contains coelacanth material (presumably of the common and contemporaneous Osteopleurus newarki), which material this refers to has never been specified nor has the referral been justified.

References- Bock, 1945. A new small reptile from the Triassic of Pennsylvania. Notulae Naturae of the Academy of Natural Sciences of Philadelphia. 154, 1-8.

Huene, 1948. Notes on Gwyneddosaurus. American Journal of Science. 246, 208-213.

Camp, Welles and Green, 1953. Bibliography of Fossil Vertebrates 1934-1938. The Geological Society of America, GSA Special Paper 42.

Huene, 1956. Palaeontologie und Phylogenie der Niederen Tetrapoden. Jena. 716 pp.

Romer, 1966. Vertebrate Paleontology. Chicago University Press. 468 pp.

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

Olsen, 1979. New aquatic eosuchian from the Newark Supergroup (Late Triassic-Early Jurassic) of North Carolina and Virginia. Postilla. 176, 14 pp.

Olsen, 1980. Comparison of the vertebrate assemblages from the Newark and Hartford basins (Early Mesozoic, Newark Supergroup) of eastern North America. in Jacobs (ed.). Aspects of Vertebrate History. Flagstaff, Museum of Northern Arizona Press. 35-53.

Welles, 1984. Dilophosaurus wetherilli (Dinosauria, Theropoda): Osteology and comparisons. Palaeontographica Abteilung A. 185, 85-180.

Olsen and Baird, 1986. The ichnogenus Atreipus and its significance for Triassic biostratigraphy. in Padian (ed.). In the Beginning of the Age of Dinosaurs: Faunal Change Across the Triassic-Jurassic Boundary. Cambridge: Cambridge University Press. 61-87.

Olsen and Flynn, 1989. Field guide to the vertebrate paleontology of Late Triassic rocks in the southwestern Newark Basin (Newark Supergroup, New Jersey and Pennsylvania). The Mosasaur. 4, 1-35.

Spamer, Daeschler and Vostreys-Shapiro, 1995. A study of fossil vertebrate types in the Academy of Natural Sciences of Philadelphia: Taxonomic, systematic and historical perspectives. The Academy of Natural Sciences of Philadelphia. Special Publication 16, 435 pp.

Saturday, July 24, 2010

Longisquama is not a dinosaur

Longisquamidae Sharov, 1970
Longisquama Sharov, 1970
L. insignis Sharov, 1970
Ladinian, Middle Triassic
Madygen Formation, Kyrgyzstan

Holotype- (PIN 2584/4) incomplete skull (~23 mm), incomplete mandibles, eight cervical vertebrae, several anterior dorsal vertebrae, dorsal ribs, scapula (12 mm), coracoid (5 mm), interclavicle? (9 mm), furcula, sternum?, humerus (13 mm), radii, ulnae (11 mm), radiale, intermedium, ulnare, pisiform, four distal carpals, metacarpals I, phalanx I-1, manual ungual I, metacarpals II (one proximal), metacarpals III (one proximal), proximal phalanx III-1, metacarpals IV (one proximal), phalanx IV-1, phalanx IV-2, phalanx IV-3, phalanx IV-4, manual ungual IV, metacarpals V, phalanx V-1, phalanx V-2, phalanx V-3, manual ungual V, scales, parafeathers
Paratypes- (PIN 2584/5) partial parafeather
(PIN 2584/6) two partial parafeathers
(PIN 2584/7) partial parafeather
(PIN 2584/9) six distal parafeathers
Referred- (FG 596/V/1) parafeather (Voigt et al., 2009)
(FG 596/V/2) parafeather (Voigt et al., 2009)
(FG 596/V/3) parafeather (Voigt et al., 2009)

Comments- Longisquama was originally described as a pseudosuchian, which at the time was used for all basal archosauriforms that were not parasuchians. Surprisingly few authors have addressed its relationships since, traditionally assuming it to be an archosaur(-iform) because of the supposed antorbital and mandibular fenestrae. More recently, most reviewers (e.g. Reisz and Sues, 2000) have been even more cautious and refer to it merely as a diapsid. The matter is especially difficult to resolve as the holotype only received a short original description with poor illustrations and has not been osteologically described since, with the exception of Peters' (2000) seemingly overimaginative attempt. Several characters have proven controversial and will be discussed first. Though originally described as having an antorbital fenestra, Senter (2003) found this was caused by breaks which were not present in the main slab, a conclusion also reached by Prum (2001). Peters (2000) and Martin (2004) both disagree however, believing it to have maxillary and promaxillary fenestrae as well. Similarly, an external mandibular fenestra was originally described, though all authors including Peters, Martin and Senter now agree this was due to damage. The mode of tooth implantation was described as acrodont by Sharov, though Martin believes it is thecodont. He provided no evidence for this in 2004, and even qualified the character with a question mark. In a later 2008 paper, Martin states the mandible had become split between slabs, and what Sharov interpreted as tooth crowns were actually entire teeth with expanded bases. Yet supposing the mandible with preserved teeth is being viewed laterally, the teeth would more probably be pleurodont since no lingual wall is apparent. Certainly the roots would be too short for thecodont teeth in any case, though they might be subthecodont if socketed. The posterodorsal skull is preserved expanding significantly past the orbit, described as two tubercles by Sharov, and interpreted as a crest by Peters and Senter. Martin (2008) believes it is merely part of the skull roof that has become disarticulated. Either interpretation seems possible. The clavicles were described by Sharov as fused ("concrescent") though a suture was illustrated. Senter and Martin agree they are fused to form a furcula, Peters thinks they merely overlap each other, and Unwin and Benton (2001) believe they are unfused (incorrectly saying this was Sharov's opinion). Senter (2003, 2004) and Peters (2000) have been the only authors to include the taxon in a phylogenetic analysis.

Longisquama a theropod? Olshevsky (1991) believed Longisquama to be a basal theropod (or in his taxonomy, a basitheropod theropodomorph), but of his noted characters for that group, it only has "generally avian appearence of the skull" (vague and unlike basal theropods), carnivorous dentition (plesiomorphic for gnathostomes), furcula (somewhat uncertain), relatively large forelimbs with pentadactyl manus (plesiomorphic for tetrapods and not found in basal theropods), and "featherlike scales" (which is problematic, as parafeathers do not seem to be scales or necessarily homologous with feathers, and scales are not homologous with feathers in any case). While the presence of a furcula would be theropod-like, Peters' (perhaps incorrect) interpretation would have it posteroventrally concave and fused along its length to the sternum, quite unlike the condition in theropods. Additional characters more plesiomorphic than dinosaurs include the absent external mandibular fenestra, tooth implantation (whether acrodont, pleurodont or subthecodont), interclavicle (if correctly identified), short deltopectoral crest, five phalanges on manual digit IV and four phalanges on digit V. It is thus near certainly not a dinosaur, theropod or otherwise.

Longisquama a bird ancestor? Another connection to dinosaurs has been the claim that Longisquama is related to the ancestor of birds. This originated with Sharov (1970), who believed the furcula and elongate forelimb scales were birdlike, but has more recently been popular among those arguing birds are not dinosaurs (beginning with Jones et al., 2000). Besides the furcula and forearm scales (which cannot be homologous with secondary feathers based on developmental data), Martin (2004) listed several other characters as being similar to birds- subdivided antorbital fenestra (absent as noted above), pointed snout (also in Coelurosauravus, simiosaurs, pterosaurs, most coelurosaurs, and numerous other taxa), "expanded cranium" (uncertain even if the supposed crest is really a displaced skull roof, as its three dimensional placement is unknown, as is endocranial size; also in Megalancosaurus, pterosaurs and coelurosaurs), elongate postorbital (vague and actually reduced in most birds, with even basal forms like Archaeopteryx having a shorter ventral ramus that ironically resembles Coelurosauravus more), absent mandibular fenestra (variable in basal birds and true of almost all non-archosauriforms), teeth with expanded roots (unverified as noted above), neck attaches low to skull (only true if the parietal crest is taken as part of the skull, and not actually true in basal birds like Archaeopteryx), strap-like scapula (also present in neotheropods, simiosaurs, pterosaurs and to a lesser extent in Coelurosauravus), elongate manus (also in pterosaurs, coelurosaurs and many other taxa), elongate penultimate manual phalanges (untrue in digit I, and only homologous in Martin's view in digit IV; also present in Coelurosauravus, simiosaurs, pterosaurs and theropods), and feathers.

Longisquama parafeather (after Voigt et al., 2009). al- anterior lobe, ml- middle lobe, pl- posterior lobe, ru- transverse ridges.

The supposed feather homologs of Longisquama have generated the most research since Jones et al. first redescribed them, and have since been more accurately described by Voigt et al. (2009). Jones et al. described a number of similarities to feathers, and it seems fitting to use Feduccia's (2002) term 'parafeather' for the structures. Though Haubold and Buffetaut (1987) proposed the parafeathers were paired and could be horizontally extended as gliding surfaces (a claim followed by Martin), there is no evidence of this and Voigt et al. noted any such 'thoracic wing' would be compromised by having the aerodynamic surfaces so distally placed. The cylindrical, tapered base is similar to follicular structures like feathers, though Voigt et al. noted some scales such as those on iguanid dorsal frills have this characteristic as well. However, the supposed transverse partitions homologized to avian pulp caps by Jones et al. (and claimed to be pedal phalanges by Peters, 2006) are actually transverse ridges on both sides of the parafeather's middle lobe. The supposed calamus walls surrounding them are the anterior and posterior lobes, which lack ridges basally (Voigt et al., 2009). While parafeathers look roughly feather-like distally in having a central shaft and surrounding vane, the actual structure is quite different. Instead of a hollow rachis and separate barbs to form the vane, Longisquama has a pair of membranes which join at their edges (Reisz and Sues, 2000) and enclose two longitudinal lobes distally, as the posterior lobe tapers out before the vane-like expansion. The shaft analog is a continuation of the boundary between the anterior and middle lobes (so is not even continuous with the basal 'calamus' as identified by Jones et al.), while the supposed barbs never separate even at the parafeather's tip and often merge (blamed on taphonomy by Jones et al.). Instead, the 'barbs' are transverse ridges in the continuous membrane. There seems to be an outer sheath on the base of each parafeather, which was homologized by Jones et al. with the sheaths on avian feathers. Resemblences to feathers thus seem limited to the cylindrical and tapered base and basal sheath. While parafeathers may be homologous to feathers at the level of the follicle, they are no more similar than the stage 1 feathers of Tianyulong and basal coelurosaurs, the quills of Psittacosaurus or the pycnofibres of pterosaurs.

Longisquama does not share any characters with birds not found in basal coelurosaurs, and can be excluded from Tetanurae based on numerous characters such as maxillary teeth extending posteriorly under the orbit, having only eight cervical vertebrae, lacking an enlarged distal carpal I+II, having phalanges on manual digit IV and having digit V, in addition to the non-dinosaurian characters noted in the previous section.

References- Sharov, 1970. Svoyeobrazaya reptiliya iz nizhnego triasa Fergany. Paleontologicheskii Zhurnal. 1, 127-130.

Sharov, 1970. An unusual reptile from the Lower Triassic of Fergana. Paleontological Journal. 1, 127-130.

Haubold and Buffetaut, 1987. Une novelle interprétation de Longisquama insignis, reptile énigmatique du Trias supérieur d'Asie centrale. Comptes Rendus Académie des Sciences du Paris. 305, 65-70.

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

Benton, 1993. Reptilia. in Benton (ed). The Fossil Record 2. London. 681-715.

Jones, Ruben, Martin, Kurochkin, Feduccia, Maderson, Hillenius, Geist and Alifanov, 2000. Nonavian feathers in a Late Triassic archosaur. Science. 288(5474), 2202-2205.

Peters, 2000. A reexamination of four prolacertiforms with implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia. 106(3), 293-336.

Reisz and Sues, 2000. The "feathers" of Longisquama. Nature. 408(6811), 428.

Unwin, Alifanov and Benton, 2000. Enigmatic small reptiles from the Middle-Late Triassic of Kirgizstan. In Benton, Shishkin, Unwin and Kurochkin (eds). The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press, Cambridge. 177-186.

Jones, Ruben, Maderson and Martin, 2001. Longisquama fossil and feather morphology. Science. 291(5510), 1901-1902.

Prum, 2001. Longisquama fossil and feather morphology. Science. 291(5510), 1899-1900.

Reisz and Sues, 2001. Longisquama does not have feathers. Journal of Vertebrate Paleontology. 21(3), 92A.

Unwin and Benton, 2001. Longisquama fossil and feather morphology. Science. 291(5510), 1900-1901.

Feduccia, 2002. Birds are dinosaurs: Simple answer to a complex problem. The Auk. 119(4), 1187-1201.

Senter, 2003. Taxonomic sampling artifacts and the phylogenetic position of Aves. Unpublished PhD thesis. Northern Illinois University. 147 pp.

Senter, 2004. Phylogeny of the Drepanosauridae (Reptilia: Diapsida). Journal of Systematic Palaeontology. 2, 257-268.

Martin, 2004. A basal archosaurian origin for birds. Acta Zoologica Sinica. 50(6), 978-990.

Peters, 2006. The other half of Longisquama. Prehistoric Times. 75, 10-11.

Renesto and Binelli, 2006. Vallesaurus cenensis Wild 1991, a drepanosaurid (Reptilia, Diapsida) from the Late Triassic of northern Italy. Rivista Italiana di Paleontologia e Stratigrafia. 112, 77-94

Martin, 2008. Origins of avian flight- a new perspective. Oryctos. 7, 45-54.

Voigt, Buchwitz, Fischer, Krause and Georgi, 2009. Feather-like development of Triassic diapsid skin appendages. Naturwissenschaften. 96, 81-86.

Monday, July 19, 2010

Patricosaurus is probably not a lizard

 First Actiosaurus, now another choristodere ex-theropod?

Patricosaurus Seeley, 1887
P. merocratus Seeley, 1887
Late Albian, Early Cretaceous
Gault Clay (reworked into Cambridge Greensand), England
- (SMC B58401) (~3 m) proximal femur (~107 mm)

Diagnosis- (after Barrett and Evans, 2002) femoral head strongly curved anteriorly; very strong trochanteric crest and intertrochanteric fossa.

Comments- Patricosaurus merocratus was based on two unassociated specimens, a sacral vertebra (SMC B58402) found before 1859 and a proximal femur discovered in the 1880's. Seeley (1887) believed both belonged to the same taxon since he thought "there was little chance of any remains of two lizards occurring" in the Cambridge Greensand, but stated the femur could remain as the type if the vertebra was found to not belong to the same taxon. Barrett and Evans (2002) redescribed the specimens and referred the vertebra to Archosauria, which makes the femur the lectotype. Although they called Patricosaurus indeterminate, they also listed several features which differed from all lepidosaurs they examined.

First row- Patricosaurus merocratus lectotype proximal femur in A dorsal, B anterior, C posterior and D proximal views. Scale = 10 mm. After Barrett and Evans, 2002.
Second row- Khurendukhosaurus femur in (left to right) ventral (flipped to have same outline as dorsal), posterior and proximal views. After Matsumoto et al., 2008.
Third row- Varanus in (left to right) dorsal, anterior, posterior and proximal views. After Barrett and Evans, 2002.

Seeley named the taxon as a new genus of lizard, more closely related to modern taxa than any other Cretaceous lizard known at the time, but outside the crown group. Patricosaurus was referred to Lacertilia incertae sedis without comment by most later authors as well. Barrett and Evans compared it to several modern lizard taxa, but found no characters that were phylogenetically useful in the proximal femur. Additionally, they could not distinguish it from rhynchocephalians, leaving them to classify Patricosaurus as Lepidosauria incertae sedis. Evans later (2003) listed Patricosaurus as a possible anguimorph without comment, perhaps because she and Barrett felt it was phenetically closest to terrestrial varanids. Barrett and Evans noted that the lepidosaur-like characters of Patricosaurus were symplesiomorphic for diapsids, correctly excluding it from turtles, plesiosaurs, ichthyosaurs and archosaurs. Choristoderes share the same femoral plesiomorphies as lepidosaurs, but were said to differ from Patricosaurus in having "narrower, more elongate, internal trochanter and an absence of obvious proximal muscle scars or strong muscle ridges." Yet the near contemporaneous Khurendukhosaurus does not have a narrower internal trochanter, has a rough insertional surface for the m. pubischiofemoralis externus (the dorsal surface is worn, so cannot be judged), and the length of Patricosaurus' internal trochanter is unknown as it is broken distally (unless they mean length in proximal view away from the head, in which case Khurendukhosaurus is in the range of modern lepidosaurs). Thus a relationship with choristoderes needs to be considered further. Of the characters listed by Barrett and Evans as variable in lepidosaurs, Khurendukhosaurus is less similar to Patricosaurus than some lizards in having almost no anterior curvature of its femoral head (instead the entire head is projected anteriorly as in Xantusia and Elgaria), is similar to the examined lepidosaurs in having weaker trochanteric crests (and thus a shallower intertrochanteric fossa), is more similar than most examined lepidosaurs (except Tupinambis and Cyclura) in having a small amount of separation between the internal trochanter and head, but is more similar to Patricosaurus than any examined lepidosaur in having a teardrop-shaped head in proximal view and in having the anteroposterior width be >95% of the dorsoventral width in proximal view. Cteniogenys (perhaps the choristodere Evans compared, as she previously redescribed it) is dissimilar in the latter three ways, while Pachystropheus is quite different in the proximally flattened head, distally placed interior trochanter and other features. Pending comparison to a greater variety of lepidosaurs (including fossil taxa), Patricosaurus is provisionally considered more likely to be a choristodere, perhaps closer to neochoristoderes than Cteniogenys.

Olshevsky (1991) stated Patricosaurus was probably an indeterminate small theropod, citing personal communication from Molnar. However, Molnar stated (pers. comm., 2001) that while he was not convinced it is a lizard, he did not think it was a theropod or even an archosaur. Thus there was a misunderstanding, and no one actually ever considered Patricosaurus to be dinosaurian based on evidence. As Barrett and Evans stated, Patricosaurus cannot be an archosaur because members of that clade have lost the intertrochanteric fossa and internal trochanter. Similarly, there is no anterior or greater trochanter, unlike theropods.

References- Seeley, 1887. On Patricosaurus merocratus, Seeley, a lizard from the Cambridge Greensand, preserved in the Woodwardian Museum of the University of Cambridge. Quarterly Journal of the Geological Society of London. 43, 216-220.

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

Barrett and Evans, 2002. A reassessment of the Early Cretaceous reptile ‘Patricosaurus merocratus’ Seeley from the Cambridge Greensand, Cambridgeshire, UK. Cretaceous Research. 23, 231-240.

Evans, 2003. At the feet of the dinosaurs: The early history and radiation of lizards. Biological Reviews. 78(4), 513-551.

Wednesday, July 14, 2010

"Yezosaurus" update

Thanks to Konishi, I've learned of yet another reference that mentions "Yezosaurus" from 1977.  This time it's a short article by Muramoto that lists the name Yezosaurus mikasaensis and attributes it to Obata and Muramoto, 1977.  Again, it refers the taxon to Tyrannosauridae and includes a photograph, but there is no diagnosis, so it is still a nomen nudum.  Based on the cover of the issue, it was published in December, meaning Muramoto's book published in November is still the earliest reference I've been able to confirm.  So unless the Obata, 1977 reference is verified or another article is located, I'm keeping "Yezosaurus" attributed to Obata and Muramoto vide Muramoto, 1977.  Konishi also revealed that "Yezosaurus" was not mentioned in the Taniwhasaurus paper because it is an unofficial name, and confirmed their species mikasaensis was intended as a new taxon and not a renaming of "Yezosaurus mikasaensis".  Anyone who wants a copy of the article with translation by Konishi can email me at .

Muramoto, 1977. Discovery of the fossil of a large reptile skull. Kaseki no Tomo. 16, 2.

Saturday, July 10, 2010

Yezosaurus- when the literature is more difficult than the identification

This was quite the troublesome entry, even though the proper exact identification was already made two years ago.  I'd like to thank Rob Taylor, Wenjie Zheng and George Olshevsky for their help.

Taniwhasaurus Hector, 1874
= "Yezosaurus" Obata and Muramoto vide Muramoto, 1977 (?)
= Lakumasaurus Novas, Fernandez, Gasparini, Lirio, Nunez and Puerta, 2002
Comments- There are three or four species in this genus, one of which (T. mikasaensis) was originally believed to be a tyrannosaurid and called Yezosaurus.
References- Hector, 1874. On the fossil Reptilia of New Zealand. Transactions of the New Zealand Institute. 6, 333-358.
Novas, Fernández, Gasparini, Lirio, Nunez and Puerta, 2002. Lakumasaurus antarcticus, n. gen. et sp., a new mosasaur (Reptilia, Squamata) from the Upper Cretaceous of Antarctica. Ameghiniana. 39, 245-249.

T. mikasaensis Caldwell, Konishi, Obata and Muramoto, 2008
= "Yezosaurus mikasaensis" Obata and Muramoto vide Muramoto, 1977 (?)
Late Santonian-Early Campanian, Late Cretaceous
Kashima Formation of the Upper Yezo Group, Japan
- (MCM.M0009; specimen of "Yezosaurus mikasaensis") (~10.3 m) (skull ~1.5 m) partial snout, sclerotic plates, partial mandibles
Paratypes- ?(MCM.A1008) two dorsal vertebrae, two proximal caudal vertebrae, distal caudal vertebra
?(MCM.M10) two dorsal vertebrae
Late Santonian-Early Campanian, Late Cretaceous
Haborogawa Formation of the Upper Yezo Group, Japan
- ?(MCM.A600) jugal, postorbitofrontal, squamosal?, parietal, quadrate, ectopterygoid, coronoid

Specimen named "Yezosaurus mikasaensis" in right lateral (A), dorsal (B), left lateral (C) and ventral (D) views. Scale = 100 mm. (after Caldwell et al., 2008)

Comments- The original partial skull of "Yezosaurus mikasaensis" (originally part of Muramoto's private collection, but later designated as MCM.M0009) was discovered in 1976 and thought to be a tyrannosaurid. It has had a confusing citation history, as the West learned about from a two page photocopy in the late 1970's to early 1980's attributing it to Obata and Muramoto, 1977. This authorship and date was used by Olshevsky (1991) and Glut (1997), though neither includes a full citation, and an extensive literature search has failed to locate any such publication. The photocopy originated from a 1977 book by Muramoto and lacks a diagnosis (hence Olshevsky listing the taxon as a nomen nudum), though it's unknown if the book contains further description which could validate the genus. Thus a citation based on this reference should be Obata and Muramoto vide Muramoto, 1977. Chure and McIntosh (1989) list the authorship merely as Obata, 1977, providing a citation for a short article about Muramoto's collection. This may actually be the correct reference for the name, depending on whether it refers to the taxon and when exactly it was published. Yomiuri (1977) also wrote a book later that year about "Yezosaurus" as a dinosaur (with Osborn's Tyrannosaurus skeletal on the cover), but again the technical content remains unknown. Chure (pers. comm. in Olshevsky, 1991) identified the remains as a mosasaur, which it was later redescribed as by Caldwell et al. (2008). Those authors named it as a new species of Taniwhasaurus, retaining the species name originally given to "Yezosaurus" (though the latter is not mentioned in the paper). If any of the 1977 publications include a description which follows ICZN rules, the authorship for mikasaensis will have to change, though "Yezosaurus" would still be a junior synonym of Taniwhasaurus. The holotype is clearly not a theropod, as it lacks an antorbital fenestra and maxillary ascending process (instead having a large prefrontal laterally exposed in that space), and further differs from tyrannosaurids and most other large theropods in having premaxilla-frontal contact, an extremely low snout, and uncompressed fluted teeth with expanded roots and no serrations. While spinosaurines are most similar among theropods, even they lack expanded roots and premaxilla-frontal contact.

References- Muramoto, 1977. [Road to Dinosaurs - Discovery of Yezosaurus mikasaensis]. North Garden, Inc. 114 pp.

Obata, 1977. [Home country collection room of the city of Mikasa and Muramoto's collection]. Natural Science and Museum. 44(1), 40-43.

Yomiuri, 1977. [The Japanese archipelago Yezosaurus ? ? ? Ryuu Itizou testimony of one million years of dinosaurs]. Green Arrow Publishing.

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

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

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

Caldwell, Konishi, Obata and Muramoto, 2008. New species of Taniwhasaurus (Mosasauridae, Tylosaurinae) from the Upper Santonian-Lower Campanian (Upper Cretaceous) of Hokkaido, Japan. Journal of Vertebrate Paleontology. 28(2), 339-348.

Friday, July 9, 2010

Macrodontophion is not a tooth

Macrodontophion Zborzewski, 1834
Lochkovian-Eifelian, Early Devonian?
Dniester Series?, Podolia, Ukraine
- shell (25 mm)

Comments- This genus was not given a species name when described by Zborzewski (1834). Macrodontophion's holotype was described as a snake tooth close to ophisaurs (actually anguid lizards) and pythons. It was also said to be similar to rhyncholites (cephalopod mandibles) and Beloptera (a spirulid cephalopod). Because Megalosaurus was mentioned in the same paragraph that the name first appears (the description proper is in the plate explanation), it was assigned to Megalosauridae by general reviews in the 1900's (e.g. Romer, 1956; Steel, 1970), and stated to be an indeterminate theropod by Weishampel (1990). Zborzewski tentatively referred it to the Jurassic, Molnar (1990) described its age as Late Jurassic or Cretaceous, and Weishampel assigned it to the Jurassic Nikolayevskaya Oblast based on personal comminication from Kurzanov. However, Nessov (1995) suggested its age was Early Devonian based on the geology of the region, Zborzewski's description of the locality as "ancient red sandstone" rich in lizard and snake teeth, comparable to the red strata in the Early Devonian Dniester Series which is rich in Porolepis teeth.

 Macrodontophion holotype in two views (after Zborzewski, 1834).

Molnar noted the insignificant distal taper was unlike theropod teeth and could not verify it was dinosaurian, though in pers. comm. to Olshevsky (2000) he stated it could be crocodilian or plesiosaurian, and in 1991 pers. comm. with Glut (1997) stated the abruptly flared base and lateral crests are similar to some shells. Sues (pers. comm. 1988 in Glut, 1997) also believed it was nondinosaurian. Nessov noted several characters which differ from theropod teeth- curvature perpendicular to plane of lateral crests (carinae of theropods); rounded apex; winding crest along inside edge of curve on long axis of tooth. Nessov believed that among Devonion fossils, Macrodontophion was most similar to the distal pectoral spine of an antiarch placoderm. While I agree the specimen is certainly not theropod, it does not resemble antiarch pectoral spines either. These spines are ironically like theropod teeth in being flattened parallel to their plane of curvature, lack the basal flare of Macrodontophion, and consist of numerous plates unlike the latter taxon. Even if most of Macrodontophion is an internal mold, the lateral crests seem to be made of one piece each and are too large to be single plates of an antiarch spine. Another possibility is the cornual process of an osteostracan or heterostracan, which are common in the Dniester Series (Dumbrava and Blieck, 2005; Voichyshyn, 2006). These are made of a single component, but still flattened in the plane of curvature. I believe an internal mold of a mollusk or annelid shell is most likely as an identification. Hyoliths, for instance, can have conical shells which are curved perpendicular to their axis of flattening, as in Macrodontophion. Yet hyoliths seem to lack the basal flare and have a more triangular section than the oval drawn for Macrodontophion. A large number of conical Palaeozoic shells are known which have controversial and problematic identifications, generally as hyoliths, scaphopods, nautiloids, cornulitids, coleolids or even worm tubes. Until Macrodontophion is examined by an expert in these taxa, it is probably best to keep it as Lophotrochozoa incertae sedis.

References- Zborzewski, 1834. Apercu des recherches physiques rationelles, sur les nouvelles curiosites Podoli-Colhyniennes, et sur leurs rapports geologiques aves les autres localites. Bulletin de la Societe Imperiale des Naturalistes de Moscou. 7, 224-254.

Romer, 1956. Osteology of the Reptiles. University of Chicago Press. 772 pp.

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

Molnar, 1990. Problematic Theropoda: "Carnosaurs". in Weishampel, Dodson and Osmolska (eds.). The Dinosauria. University of California Press. 306-317.

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

Nessov, 1995. Dinosaurs of nothern Eurasia: New data about assemblages, ecology, and paleobiogeography. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg. 1-156.

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

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

Dumbrava and Blieck, 2005. Review of the pteraspidiform heterostracans (Vertebrata, Agnatha) from the Devonian of Podolia, Ukraine, in the Theodor Vascautanu collection, Bucharest, Romania. Acta Palaeontologica Romianiae. 5, 163-171.

Voichyshyn, 2006. New osteostracans from the Lower Devonian terrigenous deposits of Podolia, Ukraine. Acta Palaeontologica Polonica. 51(1), 131-142.