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Re: Koreanosaurus, new burrowing ornithopod [Meta]



On Fri, Oct 22, 2010 at 11:26 PM, David Marjanovic
<david.marjanovic@gmx.at> wrote:


> However, they say it's pretty close to the base of Ornithopoda. Coupled with
> the instability of our current knowledge of neornithischian phylogeny, this
> makes some people wonder whether *K.* could be just outside instead of just
> inside Ornithopoda. This is why people say this should have been tested
> (and, conversely, why they don't make that complaint every time a new series
> of tail vertebrae from Patagonia is announced as a new titanosaur).


Yes, that's it in a nutshell.  The _Koreanosaurus_ paper follows the
phylogeny used by Butler &, in which Ornithopoda is defined to include
those taxa closer to _Edmontosaurus_ than to _Triceratops_.
Ornithopoda is the sister clade to Marginocephalia.  So under this
"long fuse" hypothesis, ornithopods and marginocephalians evolved
quite late in dinosaur evolution, and were not around in the Late
Triassic.  Many ornithischians that were once considered 'ornithopods'
lie outside the Ornithopoda+Marginocephalia clade - such as
heterodontosaurids, _Othnielosaurus_/_Othnielia_ and _Agilisaurus_.
So if _Koreanosaurus_ is a basal ornithopod, it lies close to the
Ornithopoda-Marginocephalia split.  Therefore, it wouldn't take much
for _Koreanosaurus_ to fall outside the Ornithopoda+Marginocephalia
clade.



Cheers

Tim