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Re: Reflections on Recent "Dromaeosaurs"



Tim Williams wrote:

<I'm willing to believe that _Achillobator_ is a good 
taxon, just one that doesn't happen to fit neatly into
existing cladograms. Burnham also suggest that
_Utahraptor_ is a chimera too, based as it is on 
scattered bones: "We see little reason to believe that
these bones come from a single species, let alone a
dromaeosaurid )p.7).">

  I have reason to believe that *Utahraptor*, based on
a variety of bones from the same formation that all
yield dromaeosaurid characters pertaining to a
particularly large animal (elongate premaxilla,
T-shaped lachrymal, mediolaterally compressed pedal
and manal claws of very large size relative to
phalanges and limbs, tibia with astragalar facet
having a sub-rectangular outline, caudal vertebrae
with elongate post- and prezygapophyses and the
prezygapophyses longer than one preceeding centrum
[reconstructed?]) suggesting they belong to a single
taxon. It has not been suggested they all belong to a
single individual. Kirkland, if you could shed light
on this animal, could you?

  I think the same problem has been encountered with
other taxa from this region and formations (Cloverly,
Moreno Hill, Cedar Mountain) where fragmentary fossils
of similar taxonomic variety can be composed into a
single, composite animal. The identity of
*Zuniceratops* is not doubted, even though the
"squamosal" isn't; *Nedcolbertia*, an intriguining
little thing, is more complete than most taxa from
this area, based on a holotype of some worth.

  I wrote:

<<so Bambi may be a distinct taxon from
*Saurornitholestes*. This is the bulk of Burnham et
al.'s differentiation, so I'm not too willing to trust
it, but it seems a likelyhood. At worst, Bambi is a
unique "species," if not a genus.>>

<So your cladogram below should probably have
_Bambiraptor_ and _Saurornitholestes_ grouping a lot
closer together. Although the _Saurornitholestes_ type
material is fragmentary and not a lot can be gleaned
from it, there is some good stuff for this genus yet
to be described.>

  I feel the avian character of the coracoid and the
frontals being more "swollen" than in velociraptorines
like *Saurornitholestes* suggest they aren't
synonymous and that Bambi falls elsewhere. Frontals
and dentary in Saurorn and Vel are more similar to
each other than either are to Deino (see Paul,
1988a,b), and by extension and pers. obs., I would add
Bambi and Archie. This suggested to me that Bambi was
closer to the avian stem than was Vel, that Vel and
*Sinornithosaurus* were closer to birds than even
Dromie. This I felt was a good concensus to the
cladism until a more repleate and rigorous analysis is
performed. I do not neccessarily feel my clade is the
truth or should have priority over any future or past
analysis.

  I'll say my piece on *Adasaurus* in a different
post.

<<
|
`--+--*Achillobator giganticus*
   `--+--*Ozraptor subotaii*
      |?-*Variraptor mechinorum*
      `--+--*Dromaeosaurus albertensis*
         `--+--*Utahraptor ostrommaysi /
            |              ostrommaysorum*
            `--+--+--*Bambiraptor feinbergi /         
      |  |               feinbergorum*
               |  |?-*Adasaurus mongoliensis*
               |  `--+--*Unenlagia comahuensis*
               |     |--*Rahonavis ostromi*
               |     `?-+--+--*Archaeopteryx
               |        |  |   lithographica*
               |        |  `--*Archaeopteryx
               |        |      bavarica?*
               |        `--Neornithes
               |?-*Sinornithosaurus millenii*
               `--+--*Deinonychus antirrhopus*
                  `--+--*Velociraptor mongoliensis*
                     `--*Saurornitholestes langstoni*
>>

  Note: Sinorn, Vel, and Bambi are radially
represented, caring for my ambiguity on they're
relationship. I changed "Aves" to "Neornithes", per
Mike Keesey's observation. Some other techincal
problems have been resolved (serial *A. bavarica,* *A.
lithographica,* and *Neornithes,* *Rahonavis,* and
*Unenlagia*) with doubt placed on the placement of
*Adasaurus* and *Variraptor.* Oddly enough, Buffetaut
and leLoeuff (1998) did not provide synapomorphies of
Vari and Dromaeosauridae, but some are apparent as
Mickey Mortimer noted in his character analysis last
month (this list).

=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.

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