29 January 2013
Leidy and Astrodon (Plus A Stegosaur?)
Leidy's "Cretaceous Reptiles of the United States" is a Smithsonian endorsed paper, basically a small book, that has no copyright restrictions, due to age, and is therefore available for download straight from mainstream sources. Typing the name straight into Google gives the book as the first result and it can be downloaded from there (or use the link provided). The section on Astrodon is rather short. Leidy notes that he only has a single tooth to examine, given to him by Johnston, and that the tooth resembles known hadrosaur teeth. As such, it makes a great deal of sense now what I said on Saturday when I mentioned that it was rather odd that Leidy would lump Astrodon teeth together in a plate with hadrosaur teeth. The fact of the matter is that Leidy simply did not have any other remains to compare it to at the time and did not realize that, despite similarities to hadrosaur teeth, he was looking at the tooth of a sauropod. O.C. Marsh would later, again, misrepresent Astrodon by giving discovered bones of Astrodon a different name (Pleurocoelus) but in 1903 John Bell Hatcher would finally pull together the two discoveries and notice that they were the same, making Astrodon the senior synonym of the two (in the east at least; Pleurocoelus, for the time being is still a distinct genus in the western US though it has been speculated to simply be another variation of the Astrodon genus). Apparently Astrodon was also a victim of mistaken identity in Portugal. Teeth discovered in the Kimmeridgian, which is Jurassic, of Portugal were identified initially as belonging to Astrodon but have since been reassigned as belonging to a stegosaur known as Dacentrurus. More study on teeth unearthed worldwide thought to belong to Astrodon is detailed along with the Dacentrurus change in this paper by Peter Galton.