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Re: Fw: [GSP1954@aol.com: MORE DINOSAUR ENERGETICS]



In a message dated 96-12-19 20:25:22 EST, longrich@stardot.com (Nick
Longrich) writes:

<< Terry Jones wrote:

 > Once again, there is NO direct evidence of endothermy in dinosaurs!!!

        Once again, Jones is most likely wrong. Although he may have seen
 photos, I am pretty sure he must not have seen the photos I have seen of
 the Chinese feathered dinosaur. They were very detailed, close-up
 photographs. They show insulatory structures, clearly. Could be fur, for
 all I know, but they are insulatory structures, not scales or a
 lizard-like crest. Anyone who has seen the photos shown to Ostrom can see
 this for themselves, it does not require any expertise or paleontological
 training to see that this is what they are.    >>

Sorry, Jones is correct in asserting that there is no >direct< evidence of
endothermy in dinosaurs. There is, however, also no >direct< evidence of
ectothermy in dinosaurs. There may be a strong connection between the
presence of hairlike or featherlike insulatory structures and endothermy, but
the connection is >not< 100% rigorous. Thus, you cannot >prove< the existence
of endothermy with the presence of insulatory structures, merely >suspect<
it.

This situation is particularly critical in tetrapod lineages in which
endothermy is known to have developed, namely, mammals and avians. Can we be
sure that the first appearance of insulatory structures (e.g., hair and
feathers) coincides with the appearance of endothermy? And--how endothermic
does a creature have to be in order to require insulatory structures? Were
hair and feathers exapted for insulation, or did they arise only after the
creature required an insulatory covering? How do you know? Too many
questions, but no living examples of borderline endothermic tetrapods to help
to answer them.