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Re: Nanotyrannus (?) fighting ceratopsian specimens videos



I, too have seen photos of specimens and casts. I have also viewed the
miniature in person (not really a resource- just cool looking). I have
also spent a decade pulling fossils out of the Hell Creek formation.
So, while we're toe to toe for secondary observations of these
specimens, I've had plenty of hands-on experience with the actual
strata, specimens and research of the Hell Creek.

There's a simple way to solve this: section the femurs. If the
histology comes out adult, then the juvenile T. rex hypothesis is
falsified. Until then, Carr's ontogeny of Tyrannosaurus remains
reliable, and "Nanotyrannus" is a nomen dubium. Larson's argument is
that he's found another small tyrannosaurid, and because it is small,
it must be "Nanotyrannus." That logic is not based on anything other
than the size of the individual. It's the same argument used when the
"Jordan Theropod" was published as a new, unknown taxon instead of
being recognized as an extremely young T. rex. "T. rex is only big!
It's a big dinosaur!" That kind of thinking seems to convey a lack of
understanding that dinosaurs were dynamic, growing, breathing
organisms, not collectible statues. You could just as easily say that
this new skeleton is a juvenile T. rex. Except there's actually
evidence supporting juvenile tyrannosaurs in the Hell Creek, based on
Thomas Carr's work. Until histology shows otherwise, "Nanotyrannus" is
dead.

There's only one ceratopsid in the Hell Creek: Triceratops. They can't
make arguments about potential novel characters until they've done a
few things first, namely histology and hi-res stratigraphy- plugged it
in to either the lower, middle, or upper Hell Creek. Then, and only
then, can they try to determine if there is a valid new taxon. Let me
set this straight: skull ornamentation is probably the *worst* feature
to base autapomorphies on. It is the most highly variable part of a
ceratopsid's anatomy as it was constantly changing throughout
ontogeny. Focusing on differences because of a curve here or a bump
there will only result in a trainwreck. Stubby horn cores, which are
known to be highly variable between growth stages and individuals, are
not a valid reason to erect a new taxon. I would accept a "sexual
dimorphism" hypothesis way before I'd accept "looks different? New
species." Larson et al. are focusing only on minor differences...a few
bumps and knobs that can be accounted for with current hypotheses
regarding variation and ontogeny, and un-prepped ischia that appear
"straight". Everything about this animal smacks of Triceratops, a very
interesting Triceratops.

Lee


Lee Hall
Paleontologist
SWCA Environmental Consultants
http://sites.google.com/site/leehallpaleo/Home
paleeoguy@gmail.com



On Fri, Nov 11, 2011 at 9:24 AM,  <GSP1954@aol.com> wrote:
>
> In a message dated 11/11/11 10:59:54 AM, paleeoguy@gmail.com writes:
>
> << A juvenile T. rex and a Triceratops with short horns. >>
>
> Having seen the specimens via photos and casts, the first is unlikely to be
> correct (despite my previous thinking) and the second is even more
> improbable.
>
> GSPaul
>
> </HTML>
>