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Temp in Cretaceous

With regard to the question on temperature estimates for T. rex--based on a
really neat interdisciplinary study that I was a part of a few years ago, it
is clear that the end Cretaceous dinosaurs, or at least parts of the global
population, were capable of surviving some cool temperatures.  The study was
in Maastrichtian sediments deposited in a delta environment on the North
Slope of Alaska.  We found a tyrannosaurid, lots of Edmontoceras, a
Pachyrhinoceras, and miscellaneous scraps of other dinosaurs.  Based on the
pollen, plant megafossils, and calcareous microfossils, we reconstructed the
environment as mild temperate, comparable to temperatures in the Pacific NW
today.  We suggested that mild frosts were probably during the long, dark,
and cool winter at these high northern latitudes.  The vegetation was all
deciduous, in contrast to the evergreen vegetation that existed in lower,
warmer, lighted latitudes in southern Canada and the U.S.  The upland
forests were deciduous conifers, and the delta was covered by horsetails,
ferns, and misc. angiosperm herbs and shrubs.  And you are right, it
certainly does suggest that at least some of these puppies were warm-blooded.