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Re: Re: More Holtz on the origin of birds



>In a message dated 95-12-08 02:17:45 EST, Thomas_R_HOLTZ@umail.umd.edu
>writes:
>
>>I would suggest that the arms of these theropods were NOT folded to increase
>>speed, but were instead folded for use in a praying mantis-like grasping
>>system.
>
>How about this:  they were folded to prevent them from banging into the knees
>when the animal ran.  A good test, of course is whether this (arm-folding) is
>true of other long-armed, fast moving theropods.

Almost all the long armed theropods had a semilunate carpal block.  The big
exception is the Ornithomimosauria, which had it primitively but (contra
Sereno) lost it before the origin of any of the known forms.  The carpus of
ornithomimosaurians and tyrannosaurids are (independantly) reduced, and
associated with the alternative transformations of their hands.

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