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Re: WHAT are segnosaurs?



Ken Kinman wrote-

>      I commend Mickey on his analysis.  It clearly casts extreme doubt
upon
> the hypothesis that therizinosauroids might be prosauropods (or
sauropods).
> I am convinced that they are indeed neotheropods.
>      However, I am still not convinced that they would form a single clade
> if Mickey did the same experiment with tetanurans.   I am not familiar
with
> Xu et al., 1999.  Did they test various hypotheses as Mickey did in the
> prosauropod experiment---for instance an analysis of major tetanuran
groups
> excluding coelurosaurian "synapomorphies" to see if the therizinosauroids
> would still group together in a single clade?  Or is the fossil record
still
> too fragmentary to perform such tests with any confidence?

I'm glad you are convinced they are neotheropods.  Xu et al. 1999 is the
description of Beipiaosaurus.  The authors include a phylogenetic analysis
with 84 characters and get the following result-

____Coelophysis
|____Ornithomimidae
 |____Dromaeosauridae
  |____Troodontidae
   |____Oviraptorosauria
    |____Beipiaosaurus
     |____Alxasaurus
      |____Therizinosauridae
They did not test the result without coelurosaurian or segnosaurian
synapomorphies.  Perhaps you would accept the following proposition-
Rauhut's 2000 thesis has the purpose of resolving basal theropod
relationships (ceratosaurs, basal tetanurines, carnosaurs, etc.).  It uses
224 characters and 51 taxa.  Segnosauria is an OTU.  What if I recoded
Beipiaosaurus, Alxasaurus, Therizinosaurus and "Segnosauridae" as separate
OTU's and deleted the coelurosaur, maniraptoran, (segnosaur-oviraptorosaur),
etc. synapomorphies?  Would this be an acceptable experiment?
First I'm going to finish a long message to the list about the thesis, which
is excellent and contains a lot of new data and ideas.  But after I send
that, I would be willing to do the segnosaur experiment.

Mickey Mortimer