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In contrast,
titanosaurs predated T-rex by only
a stage or so, in Cordillera.
Where is this?
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. [...] Lacking
co-evolutionary preparation to
withstand T-rex,
Gondawana prey could have succumbed very quickly, just as
avian quarry did
when the efficient brown tree snake entered Guam. This
theory
resembles Bakker's notion of biogeographic chaos, except that the
principal proposed agency of extinction is predation, not
disease.
And it is, sorry :-) , even more
simple-minded than Bakker's. T. rex could have wiped out titanosaurs
everywhere, you say? Then why didn't Alamosaurus die out in the first
place when T. rex evolved? Or, the other way round, why didn't it
survive the K-T and spread around the world with T. rex??? And, WHY
THE [...vertical gene transfer], did all OTHER non-neornithean dinosaurs die
out???
A devastating, global radiation of
T-rex is not a very far-fetched
scenario.
Oh yes it is. Sure. Where is the evidence???
Of course you can
say in this place that the fossil record is incomplete. But a speculation based
on no evidence isn't even testable, I fear.
The ability of ungulates to enter southern South America by the
Paleocene, and the migration of marsupials even farther, to Antarctica and
Australia, attests to a high degree of "interconnectedness" of landmasses
around K-T time. T-rex could also have spread far, and fast,
with
devastating results.
Apart from New Zealand, it could not have spread to
Africa, Madagascar and India, which were already separate from each other and
Antarctica at K-T time. India was just breaking of the Seychelles! So
what happened to the titanosaurs there?
Lambeosaurs
(Pararhabdodon) did spread into Spain just before K-T, which
indicates that Europe probably fell dry at that time. Evidence of
any tyrannosaurs has not been found from anywhere in
Cretaceous Europe.
Of course, this scenario cannot fully
explain the K-T event.
Bingo! :-)
Soon I'll
show that a common physical agency of extinction is
not necessarily implied
by the lack of a common biological agency on land
and at sea.
Sorry, my English stops here, I don't understand that
sentence.
Looking forward to your next post,
David Marjanović
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