RE: Ornithischia/Saurischia Ilium Mass Distribution Hypothesis

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

Mickey Mortimer wrote with regards to Alvarezsaurus and the mass
distribution hypothesis:

<Yes, well the palaeos drawing (by Jaime Headden) is inaccurate in that
regard.  Note the flared brevis fossa on the left process of my scan.  Jaime
doesn't have the original description this was scanned from, perhaps causing
his error.>

You are correct on the flared brevis fossa, but your drawing (I assume it
was your's because it came without attribution from your web site) also
shows an anterior missing piece. That missing piece is critical in assessing
the mass distribution, and it could very well be larger/thicker than it has
been drawn. In the meantime, I was able to get a few pictures of the
disputed ilium, and from my view the ilium looks almost bimodal, making this
a borderline case. But if you look at the ilia of the adjacent taxa in a
cladogram of aves, both have ilia with prominent cranial mass
distributions - so what am I to believe?

I hope you'll accept a draw on this one.

Kind regards,

Mike Milbocker

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Mickey Mortimer
Sent: Tuesday, April 27, 2004 3:52 PM
To: dinosaur@usc.edu
Subject: Re: Ornithischia/Saurischia Ilium Mass Distribution Hypothesis


Mike Milbocker wrote-

> Counter-example that came to my mind- Alvarezsaurus
> http://students.washington.edu/eoraptor/Alvarezsaurus%20ilium.jpg
>
> According to:
>
>
http://www.palaeos.com/Vertebrates/Units/350Aves/350.200.html#Alvarezsaurus
>
> The drawing you sent(above)has the head on the left side. I think you'll
> agree the left side of the ilium in the drawing is heavier/taller than the
> right side. Therefore, Alvarezsaurus is Saurischian - which agrees with
> orthodoxy. The palaeos drawing shows it strongly Saurischian, if the mass
> ratio is any measure.

Yes, well the palaeos drawing (by Jaime Headden) is inaccurate in that
regard.  Note the flared brevis fossa on the left process of my scan.  Jaime
doesn't have the original description this was scanned from, perhaps causing
his error.

Mickey Mortimer