RE: Ornithischia/Saurischia Ilium Mass Distribution Hypothesis

["Mike Milbocker" <mmilbocker@psdllc.com>]

Great choice, Waylon R., the Elaphrosaurus. I wasn't able to find many
examples of the ilium. But applying the plane view method to a side view of
one example, I determined that Elaphrosaurus is Saurischian. I'll admit it's
a close call, but the anterior portion of the acetabulum biases the mass
distribution toward the head, giving a Saurischian result. However, given E.
is a predator, I would have expected a much more definitive forward mass
shift - since this seems to be the case for other large predators. I suspect
the E. ilium is likely non-planar, possibly with a shelf anteriorly - I
would appreciate any comments confirming this suspicion. Meanwhile, I'll
continue the research.

My personal choice for a possible exception to the hypothesis would be
Pisanosaurus, which is believed to be Ornithischian but possesses an
anteriorly pointing pubis (a Saurischian trait). Unfortunately, the fossil
remains of its ilium are inconclusive.

Thanks very much for your comments, Mike Milbocker

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Waylon Rowley
Sent: Tuesday, April 27, 2004 12:56 AM
To: dinosaur@usc.edu
Subject: Re: Ornithischia/Saurischia Ilium Mass Distribution Hypothesis



    I flipped through The Dinosauria to find an
example among theropods that would defy your
hypothesis. I came upon a figure of Elaphrosaurus,
whose ilium seems to have subequal proportions. The
figure is dated, and may no longer be considered
accurate. Maybe someone with better information on
this element could slap down some facts for us.

Cheerio,

Waylon R.




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