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Re: Flight of _Sharovipteryx

David Peters wrote:

Point 2: The keyword "If" and "under this scenario" are not supported by evidence. If you disagree, simply provide evidence. I'd love to see it.

It's still a reasonable hypothesis, though. Just as reasonable as the assertion that the long tibia is a cursorial adaptation. Given the presence of a uropatagium, it is perfectly reasonable to suggest that the tibia length might be related to increased patagial span, more than running. And besides, long tibia are also seen in some arboreal leapers.

Point 3: Pterosaurs also have uropatagia, they walk and run as evidenced by tracks, and their tibia are typically longer than their femora, but that is a pleisomorphic character going back to preflapping taxa, like sister taxon, Sharovipteryx.

I echo Jim on this one - we don't know what the running gait was for any pterosaurs. We can make some best estimates from mechanical data, but no tracks to help us out on that one. Besides, you've already hit the point on phylogenetic constraint: if you're correct about the outgroups for Pterosauria, then the long tibia is plesiomorphic, and may not say much about gait in the in-group (they need not keep the same locomotor gait, after all, just because they inherited a tendency for short thighs and long shins).



Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280 0181 habib@jhmi.edu