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R: Status of _Caudipteryx_



----- Original Message -----
From: Mickey_Mortimer <Mickey_Mortimer@email.msn.com>
To: <dinosaur@usc.edu>
Sent: Thursday, December 28, 2000 11:08 PM
Subject: Re: Status of _Caudipteryx_

>My analysis always places it as a basal
> oviraptorosaur, more primitive than Microvenator, caenagnathids and
> oviraptorids.

More primitive than Microvenator?
I've compared only the ilium of Microvenator, Caudipteryx, and Nomingia, but
for me the ilium of Microvenator morphologically is similar to that of
Deinonychus than those of Caudipteryx, which for me has an ilium in part
similar to that of Nomingia.
Infact, the preacetabular region of Microvenator's ilium is shorter than the
postacetabular region as in Deinonychus (either AMNH 3015 Ostrom 1969 and
MCZ 4371, Ostrom 1976), while in Caudipteryx the preacetabular region is as
long as (or longer) the postacetabular region similar to that of Nomingia
(if longer) and others Oviraptorids. In Microvenator the fossa for the
origin of the M. cuppedicus is large and deep as in Deinonychus and others
Dromaeosaurids, while in Caudipteryx and Nomingia the fossa is very shallow
or absent as others Oviraptorids. Caudipteryx and Nomingia has a deep
preacetabular region that tapers ventro-anteriorly and extends as ventrally
as the pubic peduncle in Caudipteryx and a half of the pubic peduncle in
Nomingia, but in Microvenator the preacetabular region extends ventrally
only 1/4 the pubic peduncle as in Deinonychus. Both, Caudipteryx and
Microvenator has a pubic peduncle that is deeper than the ischiatic peduncle
as in Deinonychus, while in Nomingia the pubic peduncle is as deep as the
ischiatic peduncle as in others Oviraptorids, however, Caudipteryx and
Microvenator differs from Deinonychus but are similar to Nomingia in the
antero-ventrally orientation of the pubic peduncle and for the flat ventral
margin of the pubic peduncle in lateral view, which is concave in
Deinonychus and others Dromaeosaurids and convex in Oviraptorids.
In conclusion, Caudipteryx and Microvenator has a shallow ilium with a
straight dorsal margin and a pubic peduncle that are deeper than the
ischiatic peduncle. As Caudipteryx and Microvenator, Nomingia has a shallow
ilium with a straight dorsal margin, but differs from Caudipteryx and
Microvenator in having a pubic peduncle that is as deep as the ischiatic
peduncle. Caudipteryx and Nomingia differs from Microvenator in having a
preacetabular region that is as long or longer than the postacetabular
region while in Microvenator is shorter than the postacetabular region.
Moreover Caudipteryx and Nomingia has a preacetabular region that tapers
ventro-anteriorly and extends as or less the pubic peduncle.
In view of this comparison of the ilium (if right) my opinion is that
Microvenator is the most basal Oviraptorosaurs with an ilium in part again
similar to that of Deinonychus.

By
____________________________________________
Marisa Alessandro
"Volounteer of Paleontological Museum of Monfalcone"
Via Achille Grandi n°18
38068 ROVERETO (TN) ITALY
Tel:039-0464-434658 Email amaris@tin.it
____________________________________________