Dubious Morrison Dinos Described By Cope

[DD1991]

Has there been any latest word on the taxonomic status of the following taxa described by Cope:

Brachyrophus

Symphyrophus

Tichosteus lucasanus

Caulodon

As far as I can recall, Brachyrophus and Symphyrophus were listed as synonyms of Camptosaurus in both editions of the Dinosauria, but the recent recognition of the Dinosaur National Monument camptosaur as distinct from Camptosaurus raises questions about whether or not Brachyrophus and Symphyrophus are synonymous with Camptosaurus (one reference lists Symphyrophus a possible synonym of the Jurassic crocodile Amphicotylus). The status of Tichosteus relative to other ornithopods is also an open question, given that Carpenter (1998) lists the type species of Tichosteus as questionably ornithopod (although the uncertain systematic position of Drinker and Othnielosaurus within Neornithischia may make Tichosteus an indeterminate neornithischian at best), while listing T. aequifacies as a possible synonym of the turtle Glyptops. As for Caulodon, the synonymy of that genus with Camarasaurus by Osborn and Mook (1921) may be questionable because other basal macronarians have the same tooth shape as the teeth named Caulodon and the teeth of Camarasaurus and USNM 5730 (which includes craniodental remains) was not considered macronarian at the time of the paper by Osborn and Mook (1921).

Carpenter, K., 1998, Vertebrate biostratigraphy of the Morrison Formation near Cañon City, Colorado: Modern Geology, v. 23, p. 407-426.

[Regg Cato]

I don't believe there's been anything published recently, and especially since the quality of the type material is relatively poor I'd say they're likely to remain as nomina dubia for a while.

Here's a situation where stratigraphic context would be helpful.