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Early sauropods not just name changes WAS Re: Antentonitirus pro-nun-see-a-shun?
In response to Mickey's statement:
"Not that I'm against using this definition of Sauropoda, but people have to
realize it's more of a change in taxonomy than knowledge that's giving us so
many early/basal sauropods."
?A good point. _Blikanasaurus_, _Melanorosaurus_ and _Anchisaurus_ have not
suddenly become more "sauropod-like". As Mickey said, what's happened is
that the name "Sauropoda" has slid further down the sauropodomorph tree,
pulled there by the reorganization of basal sauropodomorphs. By dint of its
stem-based definition, the composition of Sauropoda is at the mercy of
_Plateosaurus_ and its relative position in sauropodomorph phylogeny.?
All well and good, but there is more to this than simple taxonomic name
shifting. This is a conceptual change of what it means to be a sauropod,
and the re-examination of these ?prosauropods? is an important step in
trying to understand the evolutionary transformations that sauropods
I realize that it has never been this black-and-white, but if one considers
Prosauropoda to be a monophyletic group that, beyond sharing a coming
ancestor with Sauropoda, had little to do with their evolution, then one is
left without much to go on for sauropod origins. However, with previous
?prosauropods? being included or considered as basal sauropods, we have a
chance to test hypotheses regarding the evolution of various sauropod
features of the skeleton.
Furthermore, the evolution of the limb skeleton in sauropods is an important
but often undervalued source of potential data for the question, ?How?d they
get so big?? Even if a more ?gradist? view of Prosauropods to Sauropods is
later shown to be incorrect or in need of modification, I think it is more
than taxonomic name shifting to re-consider the implications of the
prosauropod limb skeleton for sauropod gigantism.
For someone who is not a systematist, these changes in phylogenetic
interpretation lead to a whole new series of functional ramifications. Call
them whatever you like, and argue about what they should be called, but what
Yates, Kitching, and some others have been doing is prodding the rest of us
into re-evaluating the beginnings of the largest dinosaur giants, and that
to me is what is most significant about this recent announcement.
Matthew F. Bonnan, Ph.D.
Department of Biological Sciences
Western Illinois University
Macomb, IL 61455
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