Re: "Flight theory has legs"

[Graydon <oak@uniserve.com>]

On Fri, Jul 11, 2003 at 09:24:11PM -0700, Jaime A. Headden scripsit:
> Previous analyses indicate that the use of both manual and pedal claws
> can be exapted to the same degree, as in colugos, squirrels and other
> terrestrial sciuromorph rodents, and bats, 

This can't be extended to aviform dinosaurs, though; they don't have the
basic mammal tree-or-ground-hugging-splat posture.

> but that the size and claw shape in some bats show a greater use in
> one set than another for climbing (megachiropteran bats hang by the
> foot claws, whereas never contact the substrate with the manual
> pollecial claw) resulting in a shape dichotomy between the two.  This
> seems to be a serious issue in play, and one that should be (or should
> have been) resolved prior to the extrapolation of the thrust of the
> thesis.

Until someone finds quadrepedal bird tracks, I think the
no-substrate-contact is a pefectly decent assumption.

I am also unable to come up with a hand-claw climbing scheme that
wouldn't involve the feet at all; the shoulder anatomy wouldn't let them
hang straight down from the hands.

-- 
oak@uniserve.com | Uton we hycgan    hwaer we ham agen,
                 | ond thonne gedhencan    he we thider cumen.
                 |   -- The Seafarer, ll. 117-118.