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





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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