-----Original
Message-----
From: owner-dinosaur@usc.edu
[mailto:owner-dinosaur@usc.edu]On Behalf Of KELL00BELL@aol.com
Sent: Friday, April 20, 2001 7:46
PM
To: dinosaur@usc.edu
Subject: Starkov's theory and
extinction
Last fall Dr. Starkov proposed
that T-rex arose in response to
the
appearance of Alamosaurus in
western North America. This seems probable.
T-rex evolved great size, super-powerful jaws and robust teeth capable
of <<
Who is Dr. Starkov and where was it published?
penetrating armor.>>
Not likely. The Armor of titanosaurs is thicker
than ankylosaurids.
>>
These aspects suggest the archpredator coped with large,
armored prey such as Alamosaurus;
otherwise they seem superfluous. Bladelike
teeth probably would have always sufficed against unarmored hadrosaurs and
even ceratopsids. Ankylosaurs alone were unlikely to have spurred the
advent
of T-rex, or such theropods would
have appeared much earlier. In contrast,
titanosaurs predated T-rex by
only a stage or so, in Cordillera.
True, Alamosaurus was
absent in the better-known T-rex habitats.
It
did, however, live in inland areas at least as far north as Wyoming,<<
? What sauropod material? I’d be very interested
in finding out.
and
therefore may never have been very far from the Hell Creek, etc.
environments. Species are said to evolve in isolation and spread.
Originally, T-rex could have
filled the titanosaur hunter niche, then spread
to the coastal floodplains, displacing the albertosaurs (which could not
stand up to the archpredator in battles over territory or in competition for
food.) Ornithiscians, of course, also felt the effect. As Starkov
noted,
ceratopsids had to become larger to survive T-rex.
The replacement of
Euoplocephalus with Ankylosaurus,
which he neglected to mention, is another
example of T-rex-driven size
increase.
What makes Starkov's theory especially interesting is
its potential
relevance to dinosaur extinction. If T-rex
was well-adapted to hunt
titanosaurs, the results could have been devastating if or when it gained
access to the titanosaur-dominated faunas of Gondwana. <<
I would not be a bit surprised if a tyrannosaurid
was found in South America.
Tracy L. Ford
P. O. Box 1171
Poway Ca 92074