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Re: Reflections on Recent "Dromaeosaurs"



Jaime A. Headden wrote:


*Achillobator* [could be] an assemblage of more than one taxa (as
suggested by Burnham et al., 2000) a dromie, and
another maniraptoriform, or more.

I just looked at the _Bambiraptor_ paper and, yeah, the authors raise this as a possibility. 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)."


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.


As for _Adasaurus_, the obturator process is about half way down the the ischial shaft, so more distally located compared to other dromaeosaurids (except _Achillobator_). This specimen apparently comes from a "pathologic individual" (says Norell and Makovicky), but I don't know why.

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



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