[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Ah ha! That's where therizinosaurs came from
On 8/15/2011 11:43 AM, Mike Keesey wrote:
On Sun, Aug 14, 2011 at 9:42 PM, Tim Williams<firstname.lastname@example.org> wrote:
> The biggest problem with GSP's "neoflightless" hypothesis is this: It
> proposes that tree-dwelling theropods had plenty of time to evolve an
> extensive list of "flight-related" characters (advanced
> scapula-coracoid morphology; foldable forelimbs; shorter and distally
> stiffened tails; large contour feathers on the limbs and tail; etc).
> But over this same time, these tree-dwelling theropods didn't get
> around to evolving any arboreal characters. I find this perplexing.
That's only a problem if you assume that "trees-down" is an essential
part of the neoflightless hypothesis. It doesn't seem to me that it
is. The neoflightless hypothesis may still be valid if avialans
(apomorphy-based sense) developed flight from the ground up.
It is also possible that cursorial ground foragers roosted nightly in
easily climbable trees (such as cycads) -- this lifestyle could utilize
both passive and active paths to powered flight simultaneously.