Re: Thou Shalt Not Climb!

["T. Michael Keesey" <keesey@gmail.com>]

On 6/29/07, mariusromanus@aol.com <mariusromanus@aol.com> wrote:
> Were basal birds up in the trees before they had the modern traits we
> now use to define a bird as arboreal???  If yes, what were the traits
> that allowed them to be there?  If not, then why did selection favor
> characteristics for an arboreal lifestyle?

Aren't most terrestrial vertebrates (below a certain size) capable of
getting into trees? There's even at least one non-tetrapod capable of
it: mudskippers.

I would imagine that archosaurs (and amniotes and crown-tetrapods)
have "ability to get into a tree" as the ancestral condition, only
absent in some lineages due to derived conditions (large size,
fossorial or aquatic adaptations, armor, etc.).

Seeing as few pan-avian subclades have derived conditions like these
(except for "large size"), and seeing as they all began life at a
relatively small size, I would think most were capable of getting into
trees. The preconditions for arboreality are pretty old, I think.
--
Mike Keesey