Re: Bipedalism and Arboreality.

[Stephen_Gatesy@Brown.edu (Steve Gatesy)]

Jaime Headden wrote:

>  Not to cause a furror, but Feduccia has proposed
>that birds possess their sprawled hips (the knee is
>not held parallel to the vertical [sagittal] plane)
>but factor of their having developed from a sprawling
>ancestor. Not that I see this as the most likely
>possibility of an evolutionary phenomenon, it does
>raise the question -- why does the hip sprawl in
>birds?

This feature is highly variable among living birds, and very difficult to
measure.  Cursors such as guineafowl are relatively narrow-bodied.  Based
on X-ray films, they hold their femur only 10-15 degrees away from the
sagittal plane.  I don't think even Alan Feduccia would consider this
"sprawling".  On the other hand, waterfowl are relatively narrow between
the hips and wide-bodied.  This shape could merely be a specialization for
floating, rather than for walking or running.  I see no reason to
reconstruct basal birds as particularly wide-bodied.

Also, I wanted to thank Tim Holtz for the all the references to my work.
If you can't find any of it during a search, it's because he's spelled my
name wrong (GatESy, not GatSEy)!

Steve

Stephen M. Gatesy
Dept. of Ecology & Evolutionary Biology
Box G-B209
Brown University
Providence, RI 02912
401-863-3770
401-863-7544 (fax)