Trachodon (Pteropelyx) Marginatus Ulna And Radius

''Trachodon'' (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.Leidy, J. (1856). "Notice of remains of extinct reptiles and fishes, discovered by F. V. Hayden in the Bad Lands of the Judith River, Nebraska Territories." ''Proceedings of the Academy of Natural Science Philadelphia'', 8(25 March): 72–73. It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists.Creisler, B.S. (2007). Deciphering duckbills. in: K. Carpenter (ed.), ''Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs''. Indiana University Press: Bloomington and Indianapolis, 185–210.

Despite being used for decades as the iconic duckbill dinosaur, the material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double rootHatcher, J.B., Marsh, O.C. and Lull, R.S. (1907). ''The Ceratopsia''. Government Printing Office, Washington, D.C., 300 pp. ), and its describer, Joseph Leidy, came to recognize the difference and suggested limiting the genus to what would now be seen as ceratopsid teeth. Restricted to the duckbill teeth, it may have been a lambeosaurine.Sternberg, C.M. (1936). The systematic position of ''Trachodon''. ''Journal of Paleontology'' 10(7):652–655.

History and classification

In 1856, Joseph Leidy received fragmentary remains from the Judith River Formation, collected by Ferdinand Vandeveer Hayden. From these bones, he provided the first names for North American dinosaurs: '' Deinodon'', '' Palaeoscincus'', ''Trachodon'', and '' Troodon'' (then spelled ''Troödon''). The type species of ''Trachodon'' is ''T. mirabilis''. The generic name is derived from Greek τραχυς, ''trakhys'', "rough", and όδον, ''odon'', "tooth", referring to the granulate inner surface of one of the teeth. The specific name means "marvelous" in Latin.

''Trachodon'' was based on ANSP 9260, seven unassociated teeth, one of which had double roots. With better remains from '' Hadrosaurus'', he began to reconsider his taxonomy, and suggested, at least informally, that ''Trachodon'' should refer to the double-rooted tooth, and the other teeth should be referred to ''Hadrosaurus''.Leidy, J. (1868). Remarks on a jaw fragment of ''Megalosaurus''. ''Proceedings of the Academy of Natural Science Philadelphia'' 20:197–200. In the Bone Wars that followed, and their wake, the taxonomy of ''Trachodon'' and its relatives became increasingly confusing, with one author going so far as to sink all known hadrosaur species into ''Trachodon'' except for '' Claosaurus agilis'',Hatcher, J.B. (1902). The genus and species of the Trachodontidae (Hadrosauridae, Claosauridae) Marsh. ''Annals of the Carnegie Museum'' 14(1):377–386. but as new material was described from the Rocky Mountain region, Alberta, and Saskatchewan, later authors began progressively restricting the reach of this genus.Gilmore, C.W. (1915). On the genus ''Trachodon''. ''Science'' 41:658–660.

By 1942, and the publication of the influential Lull-Wright monograph on duckbills, its holotype was regarded as "typical of all the genera of hadrosaurian dinosaur", except for the roughened margin that gave it its name, and that they regarded as due to the tooth having not been used (p. 149).Lull, R.S., and Wright, N.E. (1942). Hadrosaurian Dinosaurs of North America. ''Geological Society of America Special Paper 40'':1–242. The name is no longer in use, except in historical discussions, and is considered a ''nomen dubium''.Coombs, Jr., W.P. (1988). The status of the dinosaurian genus ''Diclonius'' and the taxonomic utility of hadrosaurian teeth. ''Journal of Paleontology'' 62:812–818.Weishampel, D.B., and Horner, J.R. (1990). Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria''. University of California Press:Berkeley, 534–561. Horner, J.R., Weishampel, D.B., and Forster, C.A. (2004). Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria (second edition)''. University of California Press:Berkeley, 438–463.

In 1936, paleontologist Charles Sternberg compared the holotype teeth of ''Trachodon mirabilis'' to those of more completely known hadrosaurids and noted that they were most similar to those of lambeosaurines. It has been reported that paleontologist John R. Horner also found that ''Trachodon'' teeth compare well with the teeth of lambeosaurines, specifically ''Corythosaurus'', though they also share similarities with the genus '' Prosaurolophus''.Olshevsky, G. (1997)
"Re: Ye Olde Duckbill Dinosaur"
discussion group, The Dinosaur Mailing List, 8 August 1997. Accessed 6 April 2013.

Species

Numerous species have been referred to this genus, mostly before World War I. Only those originally named as a species of ''Trachodon'' are considered here.

Type species:
''T. mirabilis'' Leidy, 1856

Other species:
*''T. amurense'' Riabinin, 1925Riabinin, A.N. (1925). A mounted skeleton of the gigantic reptile ''Trachodon amurense'', nov. sp. ''Izvest. Geol. Kom.'' 44(1):1–12. ussian/ref>(based on IVP AS collection, a partial skeleton from Upper Cretaceous rocks of the Amur River banks of Heilongjiang in northeast China, amended to ''T. amurensis'' and now the type species of '' Mandschurosaurus'')Riabinin, A.N. (1930). ''Mandschurosaurus amurensis'', nov. gen., nov. sp., a hadrosaurian dinoasur from the Upper Cretaceous of Amur River. ''Mémoir II, Société Paléontologique de Russie.'' ussian/ref>
*''T. cantabrigiensis'' (''nomen dubium'') Lydekker, 1888Lydekker, R. (1888). Note on a new Wealden iguanodont and other dinosaurs. ''Quarterly Journal of the Geological Society of London'' 44:46–61. (based on BMNH R.496, a dentary tooth from the late Albian-age Lower Cretaceous Cambridge Greensand, Cambridgeshire, England, regarded as a dubious early hadrosaurid)
*''T. longiceps'' (''nomen dubium'') Marsh, 1897Marsh, O.C. (1897). Vertebrate fossils of the Denver Basin. ''U.S. Geological Survey, Monthly'' 27:473–527. (based on YPM 616, a large right dentary with teeth from the late Maastrichtian-age Upper Cretaceous Lance Formation of Wyoming, U.S., later assigned to ''Anatotitan'')
*''T. marginatus'' (''nomen dubium'') Lambe, 1902Lambe, L.M. (1902). On Vertebrata of the mid-Cretaceous of the Northwest Territory. 2. New genera and species from the Belly River Series (mid-Cretaceous). ''Contributions to Canadian Paleontology'' 3:25–81. (based on NMC 419, disassociated postcranial material; later made the type species of the genus ''Stephanosaurus marginatus''Lambe, L.M. (1914). On a new genus and species of carnivorous dinosaur from the Belly River Formation of Alberta, with a description of the skull of ''Stephanosaurus marginatus'' from the same horizon. ''Ottawa Naturalist'' 28:13–20. and then referred to '' Kritosaurus'' as ''Kritosaurus marginatus'', which is not supported by later reviews.)
*''T.'' (''Pteropelyx'') ''selwyni'' (''nomen dubium'') Lambe, 1902 (based on NMC 290, a dentary with teeth, from the Dinosaur Park Formation of Alberta; too fragmentary to assign beyond Hadrosauridae)

Paleobiology

As a hadrosaurid, ''Trachodon'' would have been a large, bipedal/ quadrupedal herbivore.

See also

* Timeline of hadrosaur research
* '' Eotrachodon''

References

{{Taxonbar, from=Q1060870

Late Cretaceous dinosaurs of North America
Hadrosaurs
Nomina dubia
Fossil taxa described in 1856
Taxa named by Joseph Leidy
Paleontology in Montana
Campanian genus first appearances
Campanian genus extinctions
Ornithischian genera