And then, if you head over to the Proceedings of the Royal Society B's website, you can download Eocursor's disappointing short description. It's important because it's the most complete known ornithischian from the Late Triassic. It's skeleton is 25% complete, including a complete pelvis and leg, as well as a mandible and pieces of the pectoral girdle and arm. According to the authors, Eocursor is more derived than the heterodontosaurs and forms an outgroup to the Genasauria (Thyreophora + Cerapoda). The implications here are fairly severe: knocking the heterodontosaurs down to "most basal ornithischian" effectively knocks the idea of a monophyletic "Heterodontosauriformes" (Heterodontisauridae + Marginocephalia) down. Also, the authors assert that ornithischians as a group did not proliferate until the Early Jurassic, after the Triassic-Jurassic extinction left a bunch of herbivorous niches open.
So while saurischians got an early start, what with their carnivory (theropods) and hugeness (sauropodiforms), ornithischians were living in the shadow of the more prolific herbivorous archosaurs and therapsids like dicynodonts and aeteosaurs. It wasn't until those groups bit the big one that ornithischians were able to max out their potential during the Jurassic era.
So, two interesting finds to report today. And one of them is free online! Now, if only Nature would wise up. Looks like I've got to make a trip to the UAA library...
2 comments:
That's one big turkey . . . Er . . . Raptor. Kinda looks like a Weka, actually.
http://en.wikipedia.org/wiki/Weka
damn! tha's a huuuuuge bitch!
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