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Re: Segnosaurs again [was Oviraptors]



Dinogeorge wrote (Don't it give you a warm fuzzy to be arguming again, George?:)
>How swiftly we forget that a number of what are now considered prosauropods
>were once classified as coelurians:
        How swiftly we forget that _Basilosaurus_ was named as a lizard,
tyrannosaurs were considered carnosaurs, birds were considered closer to
mammals than to crocs, dinosaurs were thought to have been killed by a great
flood six thousand years ago...

>The similarities of some features of _Alxasaurus_ and _Erlikosaurus_ material
>to features found in some coelurian genera can easily be explained as
>convergence,
        You could just as easily explain the similarities between humans and
chimpanzees as convergences as well. This is something you never seem to get
in this (interminable) argument: Just because you *can* explain them as
convergences doesn't mean you should. Look for the explanation which best
fits the available evidence, with the fewest unjustifiable assumptions and
the least number of untestable hypotheses.
        Therizinosaurs are coelurosaurs.
        Once again, what the begumbus is a "coelurian"?

>I've read that paper several times and I have yet to find >any< feature of
the >skull of _Erlikosaurus_ that bars a prosauropod ancestry for  segnosaurs,
        That's not relevant. It is the shared derived characters which
elucidate phylogeny, not whether or not prosauropods *could* be their
ancestors or not. Heck, if you wanna stretch it, all theropods *could* be
descended from prosauropods, especially as you describe them!

>In _Alxasaurus_ the two carpal elements that become the so-called
"semilunate" >carpal in _Therizinosaurus_ are still unfused
        Ontogenetic? Bones have been known to fuse late in ontogeny. In any
case, the form of the bone is clearly there. Which prosauropods have a
semilunate carpal block?

>on the other hand, I consider the structure of the segnosaur foot as making it
>virtually impossible for coelurians or any other theropods above the level of
>_Herrerasaurus_ to be segnosaur ancestors.
        Until you can come up with a convincing explanation for how this
works, I simply cannot believe it.

>As soon as I find anything in the literature convincing of a theropod
>relationship for segnosaurs, I'll let everyone know.
        I believe you once quoted to me: "They cannot see who do not open
their eyes."
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      Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock TX 79409
      "The cost of living hasn't affected its popularity." - Unknown