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THE VALIDITY OF TROODON AND SOME MUSINGS ON WHAT IS AND IS NOT A SCIENTIST
TROODON vs STENONYCHOSAURUS
Jeffrey Martz wrote (in reference to me stating that it is probable there are
more than one North American theropod with the _Troodon_ tooth type):
<<Possible, but what makes you say "probable?" Teeth are no
different then any other part of the skeleton; some are diagnostic for a
particular group, some are not.>>
I say probable simply because of the numbers. At that time, there were
probably three tyrannosaurs running around, at least two dromaeosaurs
(possible 3 or 4), two elmisaurs, three or four ornithomimids and countless
herbivores, yet there is a single saurornithoidid? Seems a little bit odd,
especially since there were three running around Mongolia at the same time.
Additionally, it seems unwise to assume a priori that there was a single
species when hardly complete specimen has ever been discovered in North
America, we just don't know yet.
<<Yes, perhaps one day a "_Troodon_" tooth will be found in situ in a
theropod jaw belonging to an animal other then _Troodon_. However, this
could be true of ANY diagnostic skeletal element for any dinosaur.>>
I think you mean that a _Troodon_-looking tooth will be found in an animal
other than _Stenonychosaurus_. I think this has already taken place, ie
_Saurornithoides mongoliensis_ which has teeth that could easily be
interpereted as belonging to _Troodon_ (we have to take into account
individual variation etc), but comes from an animal quite a bit different
from the North American form (_Stenonychosaurus_).
<<Some tooth types, and many other skeletal element (ribs for example) are
known from more complete skeletons to be fairly uniform and un-diagnostic.>>
This is somewhat true. I wouldn't say undiagnostic, simply diagnostic to a
point. Like ankylosaur teeth are diagnostic to a point. Additionally, I
believe saurornithoidid teeth are diagnostic to a point.
<<However, this is not the case with _Troodon_, or for that matter,
_Aublysodon_. The teeth are very unusual and derived, and in the absense of
any other cranial material from different species with such teeth, diagnosing
taxa with them is no more strange then assigning ceratopsian species based on
fairly complete skull material, but lacking postcrania.>>
Absolutely untrue. Ceratopian postcrania seems to be rather homogenous
(except in _Chasmosaurus_), as do saurornithoidid teeth.
<<One could make the assertation that an isolated ceratopsian skull should
not be lumped with a complete ceratopsian skeleton with a identical skull
because later discoveries could reveal a species with identical skulls, but
very different postcrania.>>
You're comparison is wrong. What happened with _Stenonychosaurus_ and
_Troodon_ is something more akin to sinking _Triceratops_ into _Agathoumus_
or (god forbid..) _Diclonius_, or dumping _Gorgosaurus_ for _Deinodon_,
_Edmontosaurus_ for _Trachodon_ etc...
<<New discoveries can always change things, but _Troodon_ and _Aublysodon_
teeth are very unusual, and for the time being they seem to be diagnostic.>>
Yes, diagnostic to a point, but you can't tell me with a straight face that
you are 100% certain that _Troodon_ and _Stenonychosaurus_ came from the same
animal, you cannot even tell me with 50% certainty.
<<Also keep in mind that Phil Currie knows Judithian theropods, particularly
thier teeth, better then about anyone (having examined hundreds), and he
valid taxa. His opinions should not be discarded so lightly.>>
I am not saying anything against Phil Currie. He is certainly right in
assigning _Troodon_ to the same kind of animal as _Stenonychosaurus_, it is
simply my opinion that he erred when synonymising the two.
After reading some of the comments in support of Darren Tanke and the RTMP
bulletins, I believe that the whole mess comes down to simple editorial
mistakes and crotchity semantics. It is my opinion that anyone who lovingly,
and rigorously pursues science is a scientist. It does not matter what your
'profession' is, hey, I work in a grocery store, but I still call myself a
scientist. I believe that everyone on this list is a scientist to some
degree or another, especially Darren who pursues science lovingly and
rigorously as a profession which I know most of us on this list cannot say
Perhaps the RTMP's administration was annoyed because Darren doesn't have a
phd. They should be reminded however that quite a few respected dinosaur
scientists don't have phd's in vert paleo, George Olshevsky, Greg Paul and
John Horner among them.
I am sure this is what Steve Cole had in mind when he edited Darren's post
for Dinosaur Discoveries ish 5, Darren lives up to every definition of
scientist I know, and should be regarded as such even though phd isn't part
of his title.
Generic characters [of _Velociraptor_]-Skull and jaws of diminutive
megalosaurian type, cranium abbreviated; orbits greatly enlarged, face
elongate, four fenestrae in the side of the cranium, one fenestra in the jaw.
Teeth recurved, serrate on one or both borders, alternating in replacement;
3 ? + in premaxilaries, 9 ? + in maxillaries, 14 in dentaries.
---- Henry Fairfield Osborn