RE: Life of Birds (vertical running)

["Michael de Sosa" <ofsosa@uclink4.berkeley.edu>]

Somebody wrote:
>> Many modern birds frequently flap their wings (forelimbs) to travel up
>> tree-branches, with which they grasp with their feet (hindlimbs). Is this
>> what you mean?

David M. wrote:
>Does this mean grasping feet (at least a reversed hallux) are necessary for
>vertical running? If so, vertical running can only have arisen after
>arboreality, I'd say. How I wait for Czerkas' aye-aye dinosaur, which was
>said onlist to have such feet...

No, Ken Dial demonstrated it with ground birds (quail or something). They
aren't grasping the trunk, they are actually running up it, using the force
of their flapping to hold them onto the tree. Arboreality is not required.
Ground birds have relatively long, cursorial legs, like theropods. Also,
juvenile ground birds are capable of vertical running in this method despite
their wings being to stubby to fly... also like theropods. That's pretty
exciting to me, at least.

>        I'd also like to claim that this behaviour requires that the
>wingstroke has already evolved and therefore does not explain it. I'll stop
>here and wait for the paper, of course... :.-(

>From what I understand, the wingstroke here is not exactly the same as the
one used in flying, but advanced non-avian theropods can make both motions.
So I suppose that still needs to be explained.

Mike de Sosa
UC Berkeley