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Ozraptor (was Re: Reflections on Recent "Dromaeosaurs")

Jaime Headden wrote:

  As previously commented on, *Ozraptor* Long and
Molnar, 1999, is a Western Australian Jurassic form
that has a tibial form and depression for the
astragalar ascending process (which conforms very
closely to the actual ascending process in other
theropods) that are remarkably similar to
*Deinonychus* and *Velociraptor*, as inspected using
Norell and Makovicky, 1997, and Ostrom, 1990.
Similarly, the shape is also similar to *Utahraptor*
Kirkland et al., 1993. I would then suggest that the
animal is a basal dromie,

If Jaime is right, this would make _Ozraptor_ one of the earliest known coelurosaurs - and perhaps THE earliest. Long and Molnar (1998) give _Ozraptor_'s age as Bajocian, which makes it at least a few million years older than either _Gasosaurus_ or _Proceratosaurus_ (both of which have been touted on this list as possible coelurosaurs).

The only coelurosaur that is older is that therizinosaur lower jaw from Yunnan, China, of Early Jurassic (Sinemurian) age. But this specimen is said by some to belong to a prosauropod, not a therizinosaur.

The oblong-shaped astragalar facet of _Ozraptor_ does resemble that of _Deinonychus_, but _Ozraptor_ has something not reported (to my knowledge) in any other theropod: a central ridge (running proximodistally) in the middle of the facet, that sort of subdivides the facet into medial and lateral portions. Long and Molnar suggest the ridge was used to "lock" the ascending process (which presumably had a corresponding groove) even more securely in place.

Tim ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com