Re: T-Tip

[luisrey <luisrey@ndirect.co.uk>]

There is no reason to assume that Compsognathus is an oddity. Every small
theropod known has the three fingered pattern, the hand of Compsognathus is
basically not known while the compsognathid Sinosauropteryx is.  I second
the motion for a three fingered Compy (it is more parsimonious).
The thumb of Sinosauropteryx is greatly enlarged and specialized and digit
three is very reduced (that could count for the dissapearance of the third
digit in the European fossils).
But that doesn't mean that they couldn't be in the ancestry to
tyrannosaurs: Tyrannosaurs could have had secondarily reduced the digit
count. That may even be deducted based on the over-specialization of digit
one and atrophy of digit three.

It all depends on how much more drastically different we want to make Compy
from Sino. It could be interesting to find a very primitive tyrannosaur
with a bigger thumb than normal.

>In a message dated 1/9/00 12:55:40 PM EST, dbensen@gotnet.net writes:
>
><< The
> fossilized hand of Compsognathus is so badly preserved that it is impossible
>to
> tell by looking at it, how many fingers it had.  Since Sinosauropteryx is
>closely
> related to Compsognathus, and since Sinosaruopteryx definitely had three
>fingers,
> it's safe to assume that Compsognathus did as well. >>
>
>Not safe to assume anything in paleo! There is no evidence for a third manual
>digit in the type specimen of Compsognathus longipes; even though the third
>manual digit in most theropods has the greatest number of phalanges (four),
>not one phalanx of the expected eight (counting both hands) is preserved. But
>most of the ten phalanges of the other two digits are. Why would all the
>phalanges of the third manual digits on both hands be missing, yet almost all
>(if not all) the phalanges of the other two digits on both hands remain with
>the specimen? Also, I'm pretty sure the third metacarpal lacks the
>articulation condyles for a phalanx; it just ends in a rounded surface to
>which a functioning digit probably couldn't attach. So Ostrom tentatively
>concluded that the third digit was absent and the third metacarpal was
>vestigial.


Luis Rey

Visit my Website on http://www.ndirect.co.uk/~luisrey