Jumping proavians (was Re: Phytodinosauria status - digit loss.)

["Tim Williams" <twilliams_alpha@hotmail.com>]

Mark Shelly wrote:

>    The idea that the vertical gait would evolve in trees is at first > 
> absurd to me.

And to me too.  ABSRDly absurd, in fact.


> The animal would want to keep its body near the vertical branch (no
> long vertical pubis)

This is perhaps an explanation for the retroverted pubis in dromaeosaurs - 
an interesting idea first proposed (AFAIK) by Chatterjee.


>    Even so, jumping from or landing on branches in trees could >possibly 
> allow
> this same front to back wrist and ankle flexing motion.  Even so, you 
> >would expect to see opposable digits (which we see slightly).

Unless the proavian was not jumping between trees, but from the trees to the 
ground - a la ambush predation.


>    Mark "probably should have kept quiet" Shelly

Perish the thought.


Tim





------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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