Misleading
story
by: cbehrens40
(22/M/Fords, NJ) |
08/13/01 10:52 am
Msg: 1 of 69
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Two major problems with the
article:
1.) There were two extinctions in the
late Triassic, on at 220.7 Ma, and one near the end, at
205.1 Ma. These two extinctions affected different
groups, and in neither situation were dinosaurs nor
mammals severely affected. The second extinction is
often tied to massive volcanism, but this occurred at
201 Ma, after the extinction. The first is tied to the
Manicouigan crater, which occurred somewhere between 215
and 210 Ma, after the end-Carnian.
2.) Dinosaurs
and mammals (well, protomammals) had already
significantly diversified even in the face of stiff
competition from the reptilian-amphibian megafaunal
assemblage. Both groups had significant evolutionary
advancements over the other groups. Further, the groups
of dinosaurs Paul Olsen sites as not appearing until the
Jurassic, such as large predators, sauropods, and the
like, had already diversified by 215 Ma. I don't have
the source in front of me (I'm at work), but a French
journal in 2000 published an article by Michael Benton
about a Triassic sauropod, and Paul Sereno describes
some early sauropods in "The Evolution of Dinosaurs",
Science 268 (it was a special issue).
In
actuality, The Triassic extinction has been horribly
researched, and there is little evidence to date that
any extinction in the oceans can be linked to
extinctions on the land. I have spent a great deal of my
undergraduate years researching this one, and the data
just aren't there yet to support any statement that the
dinosaurs passively ecologically replaced the previous
megafauna, and vice versa. This whole area needs a lot
more work, and I think it should begin by asking some
more fundamental questions than the current research
asks.
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