Re: Is the Saurischia legitimate?

[Thomas_R_HOLTZ@umail.umd.edu (th81)]

>What defense do modern paleontologists have for the order <Saurischia>? What
>reason
>can anyone possibly have to keep the agile, avian, and possibly feathered
><Velociraptor
>mongoliensis> and such elephantine giants as <Brachiosaurus brancai> and
><Apatosaurus ajax> in a taxonomic relationship as close as that between
>modern dogs and cats? The primitive pelvic structure isn't a good excuse -
>it's a default feature, one that the earliest ancestors of the Dinosauria
>posessed, including that of the <Ornithischia.> It doesn't prove that a
>closer relationship exists between the theropods and the sauropods than
>between either of them and the Ornithischians. The semi-opposable-thumb claw,
>reputedly unique to the <Saurischia,> might not prove much either - In the
>last chapter of his book, <The Dinosaur Heresies,> Bakker states that there
>exists an ornithischian with such a feature, <Heterodontosaurus.> Can someone
>please tell me if he is right, or if they have found another way to support
>this centuries old classification?

Hmmm.  I think you have a problem with your "<" button...

Gauthier (1986) lists the derived conditions uniting theropods and
sauropodomorphs, repeated in Benton's chapter in The Dinosauria.

"Centuries old"???  Century, yes, but not centuries!

Incidentally, you seem to be forgetting about the prosauropods.  The
differences between Eoraptor and Thecodontosaurus are very small indeed.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084