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Re: Impact only a part of it all....
Jonathon Woolf wrote:
> A lot of reasons. First, it's definitely a very attractive idea.
> People like the idea of big, hulking creatures getting wiped out by a
> bolt from the blue. Second, it does explain the direct physical
> evidence, better than any other _simple_ hypothesis yet advanced. Also,
> Louis Alvarez is a rather strong-willed man, and more or less shouted
> down a lot of his opponents. (There are also a few ugly rumors of
> papers arguing against the impact theory being censored by major
> journals, but rumors only, no more.)
I am definitely what most people would classify as a Uniformitarian, but
neither am I completely a lover of cataclysms. It is true that the idea
of the asteroid has its appeal, but I don't think we really know enough
about impacts and their effects to definitely say that a six mile wide
asteroid would have been sufficient. I believe that it did effect life
to a great degree, but then I believe that there is evidence of other
impacts occuring in the geological record, ones of fair size, and that
life has not been effected.
As for the rumor, it is indeed ugly...the only thing I hate more than
corderoy pants is censorship....
> Food for thought: A detailed study of nondinosaurs in the Hell Creek
> (Cretaceous) and Tullock (Tertiary) formations of Montana showed that
> slightly less than half of nondinosaurian vertebrates, from fish to
> crocodilians, survived the extinction. Some groups were heavily
> affected, others only lightly, and at least one group, the champsosaurs,
> actually _increased_ in numbers and diversity. The most common group in
> the study, turtles, seems to have taken almost no notice of the
> extinction: of eighteen species present in the Hell Creek, sixteen also
> appear in the Tullock. This study is published under the lengthy title
> "Non-Dinosaurian Lower Vertebrates Across the Cretaceous-Tertiary
> Boundary in Northeastern Montana"; Laurie J.
> Bryant wrote it, and it's available from Amazon.com for something like
> ten or twelve dollars.
I actually might be able to get a hold of this myself...my university is
Montana State -- Northern, and there are deposites just outside of town
that are about 78 million years old, so there is a healthy interest in
the subject locally.
And as a side note, champosaur vertebrae are among the most common
vertebrate fossils to find out there...
John M. Dollan
Montana State University-Northern
"To make an apple pie from scratch, you must first create the
universe...." Carl Sagan