RE: the first raptor

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Mickey Mortimer wrote:

>I use it for the group
>containing Utahraptor and Achillobator, as Britt et al.'s (2001) SVP
>presentation gave good evidence the two are related.  They are both
>rather primitive looking eumaniraptorans (stout coracoid, proximally
>placed obturator process, etc.) with cervical centra that have two pairs
>of pleurocoels (like enigmosaurs).  

I wonder if this last character (and perhaps others shared between
_Utahraptor_ and _Achillobator_) is size-related?

Are _Utahraptor_ and _Achillobator_ more primitive than _Microraptor_ and
_Sinornithosaurus_?  I would guess that "primitive" in the context of
eumaniraptorans is extremely relative, since in many analyses the basal
dromaeosaurids are closest to the origin of birds.

>I wonder if my revised analysis will support the group....

Wouldn't it be wonderful if _Microraptor_ + _Sinornithosaurus_ + Aves form a
clade; _Utahraptor_ and _Achillobator_ form a second eumaniraptoran clade;
and the other eumaniraptorans (_Dromaeosaurus_, _Deinonychus_,
_Velociraptor_) form a third.  Aves a subset of the Dromaeosauridae?  I can
see a few people getting into a flap over that.



Tim