Trachodon
From Palaeos.org
Parent taxa: Ceratopsia, Neoceratopsia, Ceratopsidae (see comments below).
Taxonomic history: Diclonius Cope 1876: Cope (1883) (treated as junior synonym despite prior publication).
Type species: Trachodon mirabilis Leidy 1856.
Referred species: Trachodon altidens Lambe 1902 (nomen dubium)
- Trachodon amurensis Riabinin 1925 (nomen dubium)
- Trachodon atavus Cope 1871 (nomen dubium, synonym of Edmontosaurus regalis?)
- Trachodon breviceps (Marsh 1889) (nomen dubium) [=Hadrosaurus breviceps]
- Trachodon cantabrigiensis Lydekker 1888 (nomen dubium)
- Trachodon longiceps Marsh 1897 (nomen dubium, synonym of Edmontosaurus copei?)
- Trachodon marginatus Lambe 1902 (nomen dubium)
- Trachodon selwyni Lambe 1902 (nomen dubium)
Synonym: Diclonius mirabilis - transferred by Cope in 1883 as the name for a nearly complete specimen including a skull. This specimen was later redescribed as the type of Anatosaurus copei Lull & Wright 1942 (Coombs 1988).
Location: Judith River formation, Montana (USA).
Age: late middle Campanian (late Cretaceous).
Material: unworn crown of one large tooth, seven large and 10 small tooth fragments (ANS 9260 - Gillette, 1977). It is doubtful whether all of these are actually conspecific with the type specimen (see comments below).
Comments: Trachodon included the first hadrosaurid dinosaur specimens described from North America, and for many years the name was used to refer to many hadrosaurid specimens. Reconstructions of 'Trachodon' also appeared widely in the popular media. However, the original type material is not sufficient to allow identification of this taxon, and it must be regarded as a nomen dubium (Coombs, 1988). More complete specimens referred to Trachodon have since been redescribed as Edmontosaurus. Apart from the original type material, there are no grounds for referring any further specimens to Trachodon, including the unjustifably referred species listed above.
Technically speaking, Trachodon is not even a hadrosaurid. As originally described by Leidy (1856), the type material of Trachodon included specimens of both hadrosaurid and ceratopsid teeth. In 1858, Leidy recommended that the name "Trachodon" be reserved for the ceratopsid tooth, while the hadrosaurid specimen(s) could be referred to Hadrosaurus (Sternberg, 1936). Despite this, later authors such as Sternberg (1936) continued to use Trachodon for hadrosaurid specimens. As Trachodon remains unidentifiable to species whether hadrosaurid or ceratopsid, the question is of academic interest only.
[edit] References
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.
Gillette, D. D. 1977. Catalogue of type specimens of fossil vertebrates. Academy of Natural Sciences, Philadelphia. Part IV: Reptilia, Amphibia, and tracks. Proceedings of the Academy of Natural Sciences of Philadelphia 129: 101-111.
Sternberg, C. M. 1936. The systematic position of Trachodon. Journal of Paleontology 10 (7): 652-655.
Credits
Christopher 21:38, 30 June 2008 (PDT)
