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Re: neoflightless dinosaurs



>Oviraptorosaurs exhibit fully pneumatic vertebrae, from the axis all the
way to the middle of the tail.  To the best of my knowledge, oviraptorosaurs
are the only theropods which possess pneumatic foramina in the centra of
caudal vertebrae.  The only other theropod which displays any pneumatic
features of the caudals is *Acrocanthosaurus*, and here the pneumatization
is superficial, is limited to the neural spines and does not invade bone.<
Can't say much more than this, but there is a coelophysoid that exhibits
_extreme_ pneumatization in the caudal vertebrae. The whole vertebra is
pneumatic fossae, with the exception of the central portion of the centrum.
Peace,
Rob

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----- Original Message -----
From: "GUY LEAHY" <xrciseguy@prodigy.net>
To: <dinosaur@usc.edu>
Cc: <GSP1954@aol.com>
Sent: Sunday, September 29, 2002 10:47 AM
Subject: Re: neoflightless dinosaurs


>
> Another feature which could be interpreted as supporting neoflightlessness
in oviraptorosaurs is the extensive postcranial pneumatization.
Oviraptorosaurs exhibit fully pneumatic vertebrae, from the axis all the way
to the middle of the tail.  To the best of my knowledge, oviraptorosaurs are
the only theropods which possess pneumatic foramina in the centra of caudal
vertebrae.  The only other theropod which displays any pneumatic features of
the caudals is *Acrocanthosaurus*, and here the pneumatization is
superficial, is limited to the neural spines and does not invade bone.
> The degree of pneumatization seen in oviraptorosaurs is more extensive
than seen in *Archaeopteryx*, and oviraptorosaurs appear to be more like
extant birds in this feature.  The occurance of fully pneumatic caudal
vertebrae also suggests that oviraptorosaurs possessed abdominal air sacs,
which may indicate a more avian-like air sac lung system in oviraptorosaurs
than *Archaeopteryx*.  The occurrance of a more avian-like ribcage (large
sternal plates, ossified uncinate processes) is also consistent with the
idea that the oviraptorosaur respiratory system may have been more like
modern birds than *Archaeopteryx*.
> Guy Leahy
>
>