Temporal range: Late Cretaceous
Trachodon by cisiopurple ddrupc6-fullview
Trachodon restoration by: Cisiopurple
Scientific classification
Kingdom: Animalia
Phylum: Chordata
clade: Dinosauria
Order: Ornithischia
Suborder: Ornithopoda
Family: Hadrosauridae
Subfamily: Lambeosaurinae
Genus: Trachodon
Leidy, 1856
Species: T. mirabilis
Binomial name
Trachodon mirabilis
Leidy, 1856

Trachodon (meaning "rough tooth") is a highly dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S.A.

History and taxonomy[]

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 latter being the only name still in use. 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.

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, but as new material was described from the Rocky Mountain region, Alberta, and Saskatchewan, later authors began progressively restricting the reach of this genus.

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). The name is now on in use, except in historical discussions, and is considered a nomen dubium.


It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Despite being used for decades as the iconic duckbill dinosaur per antonomasia the material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double root), 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.

The Trachodon is a genus of Upper Cretaceous hadrosaurid dinosaurs, the species of which were famous as duck-billed dinosaurs. It was a dubious genus of the Late cretaceous due to lack of fossil material and therefore was classified as Nomen dubium. The name Trachodon means rough tooth. The phylogeny of the Trachodon dinosaur has been ignored by modern-day paleontologists on a large scale, but they were an important and unique species of the past with unusual characteristics. There are many known species under Trachodon, but Trachodon mirabilis is considered to be the type species.

They were a group of herbivores that widely inhabited the North American region. The most noteworthy characteristic of these ornithopods is their ability to chew or bring with their teeth. Based on the dental structure and the chewing habits of the ornithopods, it can be concluded that they probably have been the ancestors of modern-day herbivorous mammals like cows. The Trachodon shows all these features; hence they are regarded as an ornithopod.


As a hadrosaurid, Trachodon would have been a large, herbivore that changed postures between bipedal quadrupedal gait.