new ref

[Ralph Chapman <MNHAD002@SIVM.SI.EDU>]

A couple of comments just came out in Science (17March95, 267:1666-1667)
discussing a paper originally published by RE Barrick & WJ Showers
(Science 265:222-? 1994). In the original the authors used isotopic data
from different parts of Trex. The consistency of the inferred temperature
by the bones all around Trex they determined was not inconsistent with
endothermy - i.e. endothermy could not be rejected for Trex. Andrew R.
Millard, an archeologists from Oxford, comments on that paper and suggests
the size of the individual samples of bone included so many different
Haversian systems each, and each formed at different times, that the
statistical variance was grossly underestimated by the original authors
which increased his estimates of the temps of formation and consequently
that Trex was not a homeotherm. Not surprisingly, Barrick, Showers and
a batch of new people from Alabama (including an old friend of mine, Scott
Brande) disagreed strongly with Millard's contention that the individual
Haversion systems were that independent and showed that his same methodology
would demonstrate a cow isn;t homeothermic either.

Now, I'm not personally married to homeothermy in Trex myself, and I think
one could argue that the temperature of a Trex with a decent circulatory
system would not show very typical ectotherm patterns and might indeed,
with allometric effects and the like, converge on homoetherm patterns
whether Trex was one or not. Howver, despite being a bit removed from this
area (Jim Farlow may have lots better info and much more informed
opionions backed with actual knowledge) but it seems to me that Barrick, et
al. convincingly back up their work against Millard's argument, although
it certainly is important to look into the effect of what is essentially
the physiological equivalent of taphonomically time-averaging bunches
of Haversian systems. So lookitup if you get a chance.

Ralph Chapman, NMNH