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RE: WHAT are segnosaurs?





Mickey and Tracy,
    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?
                     -------Ken
********************************************************
From: "Tracy Ford" <dino.hunter@home.com>
Reply-To: dino.hunter@home.com
To: <dinosaur@usc.edu>
Subject: RE: WHAT are segnosaurs?
Date: Thu, 28 Jun 2001 22:45:09 -0700



How can therizinosaurs "start as stem tetanurines, then grade into basal
coelurosaurs or bullatosaurs"?  Coelurosauria is not a level of advancement
or similarity, it's a phylogenetic group.  Therizinosaurs cannot start as
non-coelurosaurs and grade into coelurosaurs unless they are the
paraphyletic grade that forms the backbone of the tetanurine tree (which is
ridiculous).
In any case, several studies have already compared therizinosaurs with
non-coelurosaurs.  For instance, both Holtz (2000) and Rauhut (2000) have
therizinosaurs along with basal coelurosaurs, carnosaurs, ceratosaurs,
herrerasaurids, etc..  It's been done and they still clade with
oviraptorosaurs.  Incidentally, Xu et al. (1999) has Beipiaosaurus,
Alxasaurus and Therizinosauridae as separate OTU's, as I'm doing with the
prosauropod experiment.<<

Thank you. I look forward to the results. What if Prosauropods where
primitive theropods (as a few of them were thought of by Huene and I think
it wasn't all do to the missinterpeted rauischid teeth) and not related to
sauropods at all? (Which I think anyway).

Tracy

Mickey Mortimer

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