Re: Bainoceratops & other basal neoceratopsians

["Steve Brusatte" <dinoland@lycos.com>]

Nick said, regarding the "jugal thingy":
>>To my knowledge, it is present in all coronosaurs, psittacosaurids,
>>heterodontosaurids (albeit reduced?), _Liaoceratops_, _Udanoceratops_,
>>_Archaeoceratops_, _Leptoceratops_, etc.

And Alessandro replied:

>And also in Chaoyangsaurus in regard to Ceratopsia, but if I remember  the
>"jugal thingy" is also present in some if not all Pachycephalosaurs, in view
>of this I think that the presence of a "jugal thingy" could be a
>synapomorphy of the Marginocephalia, in which Heterodontosaurids,
>Chaoyangsaurus, and Pachycephalosaurs possess the primitive condition with
>the absence of a dorsoventral crest, while Liaoceratops and all other
>NeoCeratopsian possess the derived condition with the presence of that
>crest. The presence of a "jugal thingy" in Zephyrosaurus and Orodromeus
>could be explained as convergence.
>Out of contest, please could someone tell me if the Bainoceratops's paper is
>available as a "pdf" file?

Well, aside from the obvious problem of precisely defining the "jugal thingy" I 
think you are right. :-))

A good illustration or photo of _Stegoceras_ will show that its jugal is marked 
by some sort of "thingy," but this is more of a horizontal ridge.  According to 
my data (and see some of the conversations I had with Alessandro and others 
onlist last summer about psittacosaurs and basal ceratopsians), the presence of 
an actual, bona fide dorsoventral crest on the jugal unites _Liaoceratops_ with 
other neoceratopsians.  

Are these two jugal prominences homologous?  I haven't seen the specimens, so I 
will refrain.  However, the illustrations that I've seen show completely 
different forms.  From my limited experience, I would say that we are looking 
at two potential different characters here: one that likely unites 
Marginocephalia or a more inclusive group (perhaps including heterodontosaurids 
and maybe even forms like _Zephyrosaurus_) and another that unites 
Neoceratopsia.

And, I'd also be interested in acquiring a pdf of the _Bainoceratops_ paper, if 
anyone has it and would be kind enough to send it my way.  Let me know offlist 
if you have it before sending it, please, as I might have to clear out some 
space in my e-mail account to receive it.

Best,
Steve

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******************************************************
Stephen Brusatte
Geophysical Sciences
University of Chicago
Dino Land Paleontology-http://www.geocities.com/stegob
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