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RE: Tyrannosaur Evolution
> From: Tim Donovan [mailto:email@example.com]
> Sent: Sunday, February 13, 2005 7:31 AM
> --- "Thomas R. Holtz, Jr." <firstname.lastname@example.org>
> > B) That being said, what limited we know of the
> > eastern North American dinosaurian fauna suggests
> > rather smaller animals in general.
> > Some possible contributing factors include:
> > 1. Smaller geographic ranges (some hypotheses
> > suggest that the largest animal size correlates with
> > the available geographic range.
> > I don't entirely buy that, but I'd thought I'd throw
> > that out)
> It's not even true. Western North America was then a
> relatively narrow north south strip of land. The east
> was considerably larger, yet Dryptosaurus was much
> smaller than T. rex.
Well, only if you limit the continent involved to "western North America"
rather than "Asiamerica". Still, as I said, I don't buy
> > > So I don't
> > > think we have a good idea of the variation that
> > existed there and then.
> > > Western North America had its own smaller basal
> > tyrannosauroid too
> > > (Labocania), and the Nemegt had Bagaraatan.
> But Labocania was only of Campanian age. So
> Bagarataan was a tyrannosauriod, not a troodont?
Bagarataan's position is far from certain, but it does come out as a basal
tyrannosauroid in my latest analyses (see Dinosauria II).
Thomas R. Holtz, Jr.
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
Building 237, Room 1117
College Park, MD 20742
Phone: 301-405-4084 Email: email@example.com
Fax (Geol): 301-314-9661 Fax (CPS-ELT): 301-405-0796