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RE: Questions




Thanks a lot! Although most of the taxa in question are still, sad to say, still undescribed, at least you helped clear some of the confusion. At least paleontologists of our age take the time to study specimens more carefully instead of those days of Marsh & Cope (I shudder to think of those unfortunate people trying to figure out how many species of Triceratops there were :) The suspense is killing me, but I hope that at least these species will be named in my lifetime!


From: "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>
To: <t_rexkwan@hotmail.com>, <dinosaur@usc.edu>
Subject: RE: Questions
Date: Wed, 14 Nov 2001 08:02:04 -0500

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Ivan Kwan
> Sent: Wednesday, November 14, 2001 6:45 AM
>
> 2) About the pachycephalosaur referred to as "Sandy", what is its exact
> taxonomic status? Is it Stygimoloch, or is it Pachycephalosaurus? I
> originally thought it was Stygimoloch, (and Luis Rey's painting &
> Pachycephalosauria Home Page seem to state so) However, refers to it as
> Pachycephalosaurus!

Study of this taxon is in the works.  Call it the "Sandy" specimen until
then.

> 3) Anybody got any idea what species the new giant caenagnathid
> is? Luis Rey
> refers to it as Chirostenotes. (Mike Triebold's page has some
> really great
> photos!!)

Species, and for that matter genus, as yet undetermined/unnamed.  Naming of
this taxon will have to wait for its deposition into a legitimate
repository.

> 4) I remember that Jack Horner excavated 3 species of
> Centrosaurine in the
> Two Medicine Formation many years back. One was Einiosaurus, one was
> Achelousaurus, but what is the third species?? It's got a nasal horn like
> Styracosaurus but it has a frill more like Einiosaurus. I
> tentatively refer
> to it as 'Monoclonius sp.' Any news on its description? It's been a vrey
> long wait because it was discovered some years back and furthermore, an
> entire bonebed of it was found. If Achelousaurus and (one of my fave
> Ceratopsids :) Einiosaurus can be named so quickly, what about this other
> one? (For more info look up Digging Dinosaurs by Jack Horner)


It is in the works.  (Please, folks, learn some patience.  A decade or two
is NOT atypical between discovery and publication.  So many specimens, so
little time!  And don't forget, we have friggin' lives, folks!!!).

> 5) Similarly, in Jack Horner's book there is some mention of a
> tyrannosaur
> somewhat intermediate between Daspletosaurus & Tyrannosaurus.
> What is it? Or
> what about the supposed 2nd species of Daspletosaurus?

This is the "Two Medicine tyrannosaurine" referred to in my recent paper on
tyrannosaurid phylogeny in Mesozoic Vertebrate Life (and on the Tree of Life
web page). In those analyses it came out unresolved relative to _D.
torosus_ and the _Tarbosaurus_-_Tyrannosaurus_ clade. In more recent
analyses of mine, as yet unpublished but featured at SVP this year, it came
out as closer to _D. torosus_. Calling it the "Two Medicine
_Daspletosaurus_" or "_Daspletosaurus_ sp." would not be inappropriate, IMIO
("in my informed opinion" :-).


Other _Daspletosaurus_-like skeletons have been found in the Dinosaur Park
Formation (being studied by Currie) and in the Southwest (studied by Carr &
Williamson).  Wait for the papers.

> 6) Still on Tyrannosaurs, are Shanshanosaurus & Stygivenator still valid
> taxa or are they generally considered juvenile Tyrannosaurus?

A paper on _Shanshanosaurus_ by Dong & Currie will be out by the end of the
year in Canadian Journal of Earth Sciences.  Currie is already on record as
regarding "_Shanshanosaurus_" as a juvenile of some larger tyrannosaurid
(although whether _Tarbosaurus_ or an as-yet undiscovered form cannot be
determined).

_Stygivenator_ is regarded by most people who have examined it recently as a
juvenile _T. rex_, but no published papers on it.


> 7) Is Megaraptor's phylogenetic position settled yet?

No.  The material published so far is so fragmentary it is difficult to say
if it is a deinonychosaur, a non-maniraptoran coelurosaur, or even a
late-surviving _Fukuiraptor_-like carnosaur.

> And what about that
> giant carnosaur that was larger than Giganotosaurus?

Paper is still being written.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796



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