Trachodon
From Greek trachys (rough) and odon (tooth); meaning "rough tooth", referring to the granulated inner surface of the hadrosaurid tooth Leidy described.
Trachodon is a dubious genus of hadrosaurid dinosaur from the Upper Cretaceous of what is now Montana in the western United States. The only species is T. mirabilis, though many others have been assigned to the genus. T. mirabilis was described by Joseph Leidy in 1856 based on a set of teeth; however, this was later shown to be a mixture of hadrosaurid and ceratopsian teeth. These fossils were unearthed in 1856 by Ferdinand Vandeveer Hayden during an expedition to the Missouri River in Montana, USA, in rock from the Judith River Formation. This formation dates to the Campanian stage of the Late Cretaceous, which lasted from 79 to 75.3 million years ago. One of the teeth, an incomplete hadrosaurid tooth, was later chosen as the holotype.
Species
Trachodon mirabilis Leidy, 1856 Nomen dubium
Type species
Latin mirabilis ("wonderful", "remarkable").
- Holotype
- ANSP 9260 , Academy of Natural Sciences of Philadelphia
- Material
- Single isolated hadrosaurid tooth (ANSP 9260), ~36 mm long and 13 mm in maximum diameter, hexahedral and slightly bent, with a smooth outer surface bearing a median ridge and a granulated inner surface; selected as the de facto holotype from a series of teeth originally described by Leidy that proved to be a mixture of hadrosaurid and ceratopsian elements.
- Horizon
- Judith River Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
- Locality
- the mouth of the Judith River where it enters the Missouri, Montana, United States
References
-
Lull, R. S.; Wright, N. E. (1942). Hadrosaurian Dinosaurs of North America. Geological Society of America Special Papers 40: 1-272. Geological Society of America. doi:10.1130/spe40-p1
Gives the holotype teeth, ANSP 9260, as collected "at the mouth of the Judith River where it enters the Missouri", in the Judith River formation.
lull1942a -
Leidy, J. (1856). Notices of remains of extinct reptiles and fishes, discovered by Dr. F. V. Hayden in the bad lands of the Judith River, Nebraska Territory. Proceedings of the Academy of Natural Sciences of Philadelphia 8: 72-73.
Erects Trachodon mirabilis on a series of teeth collected by F.V. Hayden from the bad lands of the Judith River, Nebraska Territory (modern Montana). No catalog number given in the paper.
leidy1856b -
Brett-Surman, M. K. (1989). A revision of the Hadrosauridae (Reptilia: Ornithischia) and their evolution during the Campanian and Maastrichtian. 1-272. Doctoral thesis, The George Washington University.
Agrees with Lull and Wright (1942) that the name Trachodon is unusable, and calls it a nomen dubium on a single dentary tooth.
brett-surman1989a -
Coombs, W. P. Jr. (1988). The status of the dinosaurian genus Diclonius and the taxonomic utility of hadrosaurian teeth. Journal of Paleontology 62(5): 812-817.
Treats hadrosaur taxa founded on isolated teeth as nomina dubia, Trachodon mirabilis foremost, and recommends confining the name to historical discussion.
coombs1988b -
Currie, P. J.; Rigby, J. K.; Sloan, R. E. (1990). Theropod teeth from the Judith River Formation of southern Alberta, Canada. Dinosaur Systematics: Perspectives and Approaches (Carpenter, K.; Currie, P. J., eds.) 107-126. Cambridge University Press, Cambridge. doi:10.1017/cbo9780511608377.011
Recounts how the name spread to flat-headed hadrosaurs and a family, although its type teeth came from crested forms.
currie1990a -
Prieto-Márquez, A.; Erickson, G. M.; Ebersole, J. A. (2016). A primitive hadrosaurid from southeastern North America and the origin and early evolution of 'duck-billed' dinosaurs. Journal of Vertebrate Paleontology 36(2). Informa UK Limited. doi:10.1080/02724634.2015.1054495
Notes that Trachodon, the first hadrosaurid genus described, has long been considered a nomen dubium.
prieto-márquez2016a