RE: Ornithischian vs saurischian hips

[Nick Pharris <npharris@umich.edu>]

Quoting "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>:

> > From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> > Pedro Andrade

> > What's the functional difference between the
> > ornithischian and the saurischian hip structure, if any?

> The classic one, though, deals with the orientation of the pubes. The 
> traditional saurischian orientation (pubis subvertical to
> anterior) is the primitive condition: heck, in that sense, WE have 
> "saurischian" pelves. In ornithischians (except possibly for
> _Pisanosaurus_) the pubis points backwards. This would allow an 
> increased volume for intestines without having them expand too much
> laterally, which would in turn allow the digestion of more plant material.

The other part of this that I've seen is that it shifts the weight of 
the intestines back toward the hip joint, allowing ornithischians to 
increase the size of the gut while remaining bipedal (for a time, 
anyway--given that most of the largest ornithischians did eventually go 
quadrupedal).

--
Nick Pharris
Department of Linguistics
University of Michigan

"Creativity is the sudden cessation of stupidity."
    --Edwin H. Land