Re: hair pulling, contentious replies and stegosaurs by Battattttt

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

>This model is great but I have two problems with it ;
>1) Can it be (or has it been?) proven that S. tail spikes were horizontal, as
>they are in the model? In 1987 I read that the 'beveling on the spike
>bases...shows that they diverged from the tail tip.. like a pin cushion'

The discovery which really clinched the posterolaterally (backward and
outward) orientation of the tail spikes was first described at SVP 1993.
As far as I know, there still is no published technical report on it, but
that's just a matter of time.

Although this new discovery shows that orientation, O.C. Marsh found and
described the tail of a juvenile Stegosaurus which shows much the same
thing.

>2) The model lacks a throat sac covered in ossicles, a feature almost
>definitely
>proved to exist since the discovery of the last S. (a stenops I think)
>somewhere
>in the Rocky Mountain area.

Actually, the original road kill specimen, long on display at the
Smithsonian, had proved those long ago.  The new road kill shows better the
distribution of these ossicles, though.  Another thing that the new road
kill (the one described at SVP) shows is the presence of armored scutes in
the pelvic region.

>Has an allosaur with brontosaur bite marks been found? Or is all this talk of
>tossing brontosaurs just the fruit of a diseased mind?

I have to go back and reread the article - I don't recall Bakker actually
emphasizing the tossing aspect.  I definitely do not recall sauropod tooth
marks on any bone.

What Bakker may not be off track with is the idea that, while diplodocoids
probably used their whip-like tails as weapons, brachiosaurids and
camarasaurids would be better suited for some hellacious bites.  Both
Brachiosaurus and Camarasaurus have very powerfully constructed teeth and a
decent gape, so they could potentially take out quite a chunk of flesh from
a predator.  (Or course, I still think that size was the major defense for
all sauropods).

On a related topic, I imagine that the bite of a ceratopsian was even more
severe, what with their shearing teeth and hypertrophied jaw muscles.
Maybe not the mainline of defense, but certain a powerful backup.

                                
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.