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Re: Hone and Benton 2007 (their second paper)

Besides, the manual claw function in locomotion w
ould largely have been to grip during leaping launch, in which case an "arboreal" like claw might actually be the most mechanically sound solution (making it doubly useful).

So what would the manual claws actually be gripping during a launch?

Well, I was suggesting that the might grip the ground somewhat (laterally) while pushing off. However, I was talking to Jim Cunningham about it (and took a second look at some pterosaur hands), and it actually seems as if the claws would not really be in tight contact with the ground even in those taxa with less reduced manual digits. The digits are positioned such that they can reduce lateral and posterior slipping, but the claws themselves do not look as if they would contact the ground (the fingers hyperextend in most, if not all, pterosaurs) The upshot is that mtC IV really takes the full support role in just about all of the known pterosaurs, with the bases of digits I, II, and III providing posterior and lateral support. Thus, the manual claws would be under that much less selection for terrestrial function (and that much more free for predation functions, etc).

Agreed. I guess the 'take-home' message is that, when it comes to non-aerial functions (terrestrial locomotion, feeding, mating, etc) the forelimbs and hindlimbs were employed opportunistically. It probably also varied between different pterosaurian taxa and/or with ontogeny. But for rapid progression on the ground (or as 'rapid' as a pterosaur could get) quadrupedality was probably the general rule.

I'll drink to that.


--Mike H.