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Re: Compsognathus

In a message dated 96-12-19 20:33:06 EST, jpoling@dinosauria.com (Jeff
Poling) writes:

<<    A question for the list:

    _The Dinosauria_ reports that the _Compsognathus_ specimens had two full
 digits, and a third partial digit.  Is it possible that the complete third
 digit was lost, possibly because it had Maniraptoran proportions (ie long
 and slender), and that _Compsognathus_ was actually a tridactyl
 Maniraptoran?  I do seem to recall Dinogeorge mentioning many affinities
 between _T. rex_, a Maniraptoriforme_ and _Compsognathus_..... >>

Some people have had problems accepting Ostrom's conclusion that
_Compsognathus_ had didactyl manus, I think mainly because that is such an
atypical manual configuration. Although the third digit in theropods was
relatively slender, it also had the largest number of phalanges--almost as
many as in digits I and II all together. So, given that several phalanges
from both manus are preserved in the _Compsognathus_ holotype, one might
expect to find quite a few digit III phalanges among them. Yet none are
present from either hand. Also, the third metacarpal does not seem to have an
articulating phalangeal joint distally, where it would attach to a third
finger. We may thus conclude that _Compsognathus_ most likely had at best a
vestigial third finger or none at all.

We need more specimens of _Compsognathus_ to really give this conclusion a
good test, of course.