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Body size for mammals
In light of the recent posts on body size, I thought I'd mention a paper
coming out in the May 1 Science, which according to their press release is
"***Embargoed for Release, 4 p.m., U.S. Eastern Time
***Thursday, 0 May 1998"
I assume that 0 May = 30 April.
In any case, John Alroy of the Smithsonian tested Cope's law by comparing
the masses of successive species of North American mammals, estimated from
the size of their first molar teeth (a technique verified with living
mammals), and found that the average increase from one species to the
successor species in the same genera was 9.1%. This verifies Cope's Rule,
that animal sizes tend to increase, at least for the North American
mammals, which were what Cope studied in the first place. It may not hold
for other animals.
Alroy's work went back 80 million years, and he noted a rather sudden large
increase in the upper size limit for mammals at the KT boundary. He didn't
study dinosaur body mass, but if someone could find a good proxy for body
mass, that would make a very interesting exercise.
-- Jeff Hecht