Re: Avaceratops and Ceratops (was Re: THE NEW ISH OF JVP)

["Jaime A. Headden" <qilongia@yahoo.com>]

Dinogeorge wrote:

<You can't remove Ceratops from the family
Ceratop[s]idae; the family must follow its type genus
wherever it goes. One feasible alternative is to 
isolate Ceratops in its own subfamily Ceratopinae,
different from either Centrosaurinae or
Chasmosaurinae. Maybe Avaceratops could fit into that
subfamily.>

  Unless such a group is polyphyletic. If phylogeny
supports a

*Zuni*--------\_
*Ava*--\___   /
*Cera*-/   \_/
*Chasmo*-\_/
*Centro*-/

clade, then it might be more supportable for a new
family to be coined for Chasmo and Centro, despite
previous definition and diagnoses of these as
Ceratopidae. Thusfar, we could get a new
"Chasmosauridae" for this clade, and name the node
that supports Zuni + Chasmo. There are some many taxa
within the Chasmo and Centro clades that it would be a
nightmare to try to use conventional eponyms to define
these, because you skip over several nodes and stems
for lack of clarification.

  Highly supported groups appear to be the following
(based on brief understanding of some of the presented
data on these animals from issues of JVP, the
Dinosauria, Zuni's paper, etc.):

*Pachyrhino*-\_
*Achelou*----/ \_
*Einio*--------/

  with Styraco, Centro, and Mono as successive
outgroups or a monophyletic sister assemblage
(suggested by the recent JVP paper?), so a
monophyletic grouping here can be supported; I believe
"Pachyrhinoisaurini" (or -nae?) has been suggested. If
there is a successive series, then naming a -ini, then
a -nae, leaves at least two nodes empty and unnamable
by modern convention.

  The "Chasmosaurinae" is even more complicated, being
apparently even more serially (successively) arranged
by recent phylogenies (_the Dinosauria_ comes to
mind), with some of the strongest phylogenies
apparently in support of a

*Tri*-\_
*Di*--/ \_
*Toro*--/

clade, whether or not you support Forster (1996) in
removing *"T." hatcheri* from *T.*; Toro and Tri
appear to be more closely related to each other than
either is to any other "chasmosaurine", and with
*Anchisaurus* the most basal (known) and the rest
falling more or less serially. Penta, I think, has
been supported as closer to Tri than is Chasmo,
Arrhino, or Anchi, and if so, there are at least four
unnamable nodes, unless it can be shown that all other
chasmosaurs form a monophyletic group, which I think
is unsupportable and not parsimonious.

  I gotta go, but I'll try to sit down tonight or
tomorrow and clarify my positions. Also, appologies to
Larry (and many others or you) for not supplying more
extensive citations and refs.


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.
__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com