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Re: Warm vs Cold blooded

Ok, I guess it's time for a little cross-fertilization.  About a month
and a half ago, we had a raucous good time over in VRTPaleo discussing
whether or not dinosaurs were endothermic.  At the end of that
discussion, none other than John Ruben chimed in with
a... strongly-worded, yeah... that's what I was looking for :-)
statement that we don't really have any idea whether or not dinosaurs
were endothermic.  Rather than paraphrase, I'll give you his words

    Wake up guys-- there's abundant evidence out there in the
  physiological literature that bone histology has little or nothing
  to do with metabolic rate.  It's more closely tied to growth rate
  (which also often has little or nothing to do with metabolic rate).
  Those of us concerned with determining metabolic rate in extinct
  taxa need to do a lot more homework re the physiological literature.
       The bottom line here is that there are presently NO described
  preservable features which are especially reliable indicators of
  metabolic rate in fossil taxa, dinosaurs or otherwise.  This will
  all change very soon (within the next few months), but for now,
  forget histology, trackways, posture, predator/prey ratios, growth
  rates, bone isotope ratios, etc., as indicators of metabolic
  rate. None of these stand up to close scrutiny.
       You hot-blooded dino folks-- please don't deluge me with the
  paleontological equivalent of hate mail.  If you really must know
  why the supposedly heretical dinosaurs were really probably pretty
  catholic, see:

  Ruben,J. 1995.  The evolution of endothermy in mammals and birds:  From
       physiology to fossils.  ANNUAL REVIEW OF PHYSIOLOGY, 57:69-95.

Another article you might like to find in trying to understand
thermoregulatory strategies is:

Block, B. A. and Finnerty, J. R. (1994).  "Endothermy in Fishes: A
   Phylogenetic Analysis of Constraints, Predispositions, and
   Selection Pressures", _Environmental Biology of Fishes_,

I argued over in VRTPaleo that thinking of endothermy as an either/or
characteristic is probably counter-productive.  Fish and insects
represent interesting cases for consideration in that regard.

Mickey Rowe     (rowe@lepomis.psych.upenn.edu)