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Re: dino listing
Replying to Dinogeorge's: >What
might the 12 genera right at the Hell Creek/Cenozoic boundary be? I'm
pretty sure _Tyrannosaurus_ and _Triceratops_ qualify, also
_Pachycephalosaurus_, _Stygimoloch_, _Ornithomimus_, and maybe
_Ankylosaurus_. How about_Thescelosaurus_? _Ricardoestesia_?
_Torosaurus_? It's pretty easy to compile a list of North American
Maastrichtian dinosaurs (see, for example, the stratigraphy section of
_The Dinosauria_), but figuring out which of those might be the very,
very last ones known is a bit trickier. (Unless of course you find the
I don't know if it is easy (or possible) to determine what these 12
genera might be. Many of those mentioned (e.g., Torosaurus, Stygimoloch,
Ankylosaurus, et al.) are rare below the boundary, let alone AT it.
Also, I have a hunch that some animals in the same family (such as
Triceratops and Torosaurus) may be confused or misidentified when
collected (such as that awful problem with any Maastrichtian ceratopsid
fragment being referred to Triceratops). Then, there's that nasty
problem of inflating/deflating species counts depending on the opinions
of the investigator (e.g., Triceratops horridus vs. Triceratops
prorsus). Could local environmental changes (such as mountain building,
change in climate) affect bone preservation? Could this skew counts?
It's nice that they're tracking dinosaur diversity in the Hell Creek of
Western North America, but what about the rest of the world? How was
diversity affected in Asia or South America? Or even the American
Southwest? Did all dinosaurs world-wide go extinct simultaneously? Were
there variations between northern and southern hemispheres? This was a
global extinction, and I doubt much more progress will be made (at least
in the land animal area) until global faunal counts are done. Does
anyone know if this has been done yet?
Looking forward to input on this,
The Torosaurus Home Page
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