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Re: _Achillobator giganticus_ and homoplasy

Tom Holtz wrote-

>The first thing that I would then consider is "are dromaeosaurs, as
>traditionally envisioned, monophyletic?"  That is, are _Dromaeosaurus_ and
>_Velociraptor_ and _Utahraptor_ and _Saurornitholestes_ and _Deinonychus_
>(and more fragmentary guys) really more closely related to each other than
>they are to other known taxa?  Had _Achillobator_ had just one or two
>discordant features a simple answer might be a reversal, but with this big
>mix of characters I suspect there is a larger solution.
>That is, that some "dromaeosaurs" (_Achillobator_, perhaps) might lie
>outside a clade containing birds and other "dromaeosaurs" (_Velociraptor,
>for example).  An appropriate test for this?  How about a comprehensive
>phylogenetic analysis of individual species or specimens of the pertinent
>taxa, and sort out the taxon and character distribution.

That's a great question and one that I considered as well.  My original
analysis included Dromaeosaurus, Sinornithosaurus, Unenlagia (which may be
dromaeosaurid, Norell and Makovicky 1999) and the Velociraptorinae as
separate OTU's.  There are still an annoying amount of polymorphic
characters present in velociraptorines however, and I was planning on
scoring Deinonychus and Velociraptor separately in my next analysis
(especially with the information in the new Velociraptor paper).  I'll test
Achillobator too, if I ever get the paper.  In my previous analyses,
Dromaeosaurus and velociraptorines were always sister groups, while
Sinornithosaurus and Unenlagia were successive outgroups to avians.  It will
be interesting to see what the new analyses have to say.

Mickey Mortimer