Re: BITING CERATOP{S}IANS

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>Regarding biting ceratopsians.

>On a further thread, threatened ceratopsians would have fled into the forests
>they inhabited. I don't think any ceratopsians are known from plains, pampas,
>grasslands or savannahs, can anyone prove otherwise?

A few people addressed the problem of open land fossils.  One point I
didn't notice (sorry if I missed it) was the fact that, during the
Mesozoic, there was no grass.  There must have been some non-forested land,
but what vegetation covered that land is hard to say.  Ferns, perhaps.  In
any case, no pampas, grasslands, or savannahs (by definition) during the
Cretaceous.

>CERATOPSIANS DID NOT FORM DEFENSIVE RINGS

That's mighty absolute of you.  I would agree that substantial evidence for
defensive rings is not there, but exactly how would you demonstrate
evidence for or against this kind of behavior in the fossil record?

>Note that the fighting Velociraptor (a juvenile, therefore possibly
>inexperienced)

Juvenile?  How was that determined?  From what I know of it, it is not
appreciably smaller than the type specimen.  Maybe the folks in NYC have
some new evidence to the contrary, but I haven't heard of it.

>displays unambiguously UNCINATE PROCESSES.

Actually, I would say "ambiguously", until some really decent photos of the
prepared specimen are published.  I'm willing to accept that they might be
there, but until I see the specimen in real life, or some close-up photos,
I remain skeptical.

>Mike Howgate thinks
>that the fighting V.- P. pair are good evidence that Velociraptor was a
>solitary hunter, but that's another story...             who will rise to the
>challenge?

Why would Velociraptor mongoliensis, a taxon which lived in or near desert
regions where the largest prey items are big protoceratopsians and small
ankylosaurids, be expected to pack hunt?  I think a better case can be made
for Deinonychus being a pack hunter.  However, extending this idea to
another genus which, albeit closely related, lived in a very different
environment is questionable.

For a comparison: lions and leopards sometimes live in the same geographic
range and are very similar anatomically.  However, while leopards are
almost all solitary hunters, and lions display both pack hunting and
solitary hunting, depending upon their age, sex, and social status.

>Tom, why are you in exile?

The "Exile" in my signature refers to my current, self-imposed "exile" from
vertebrate paleontology.  Although my doctoral work was in theropod
dinosaurs, I am currently employed by the USGS not to do Mesozoic
vertebrates but to work on late Cenozoic ostracodes (microscopic bivalved
crustaceans).  Thus, I can't spend my daylight hours working on dinosaurs
the way I'd like to.  Even so, I do have access to an excellent earth
science library and the Internet.

However, my current contract runs out in about five and a half weeks.
Depending upon certain circumstances, I may have a lot more free time than
I'd like... :-(  I hope to hang on to this e-mail account for a while - if
not, I do have a couple of backups.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.