Re: Flight of _Sharovipteryx

[Michael Habib <mhabib5@jhmi.edu>]

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).

Cheers,

--Mike


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