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Re: HYPSILOPHODONT MONOPHYLY



Pete Buchholz wrote:

Also, the authors seem to sink three very distinct species into one in regard
to Yandusaurus hongheensis, lumping "Yandusaurus" multidens and Agilisaurus
louderbacki all into the same species with Y hongheensis.... In my opinion
it's like sinking Camptosaurus and Parasaurolophus into Iguanodon...


Discussion? Anyone have opinions?

Carpenter (1994) presents a good case for regarding _Yandusaurus multidens_ as a young individual (and therefore a junior synonym) of _Yandusaurus hongheensis_. Carpenter (1994) sets out the features which distinguish _Y. multidens_ from _hongheensis_ and, based upon ontogenetic changes observed in a growth series of _Dryosaurus altus_, claims that all the features that define _Y. multidens_ as a separate species are in fact hallmarks of an immature individual. Aside from smaller body size, these features include: enlarged orbits; shorter muzzle; scapula longer than humerus; absence of a ridge on the ventral surface of the coracoid; and humerus narrower at the proximal end and exhibiting less curvature of the shaft (Carpenter, 1994).


As for the headless _Othnielia_... I heard a very sad story about how the skull of _Othnielia_ was stolen ("head-hunted") before the specimen could be completely excavated. The specimen was discovered and its location noted, but when a team returned to begin excavation, the skull had already been excavated (presumably by private collectors) and has never been seen again. Is this a true story? If so, it has my blood boiling...


References

Carpenter, K. (1994). Baby dinosaurs from the Upper Jurassic Morrison Formation of Dinosaur National Monument. p.288-297. In: Carpenter, K., Hirsh, K.E., and Horner, J.R. (Eds.). Dinosaur Eggs and Babies. Cambridge Univ. Press, U.K.
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