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MORE DINOSAUR ENERGETICS



This is a response to the responses by Rowe and Jones to my long posting,
which showed that the latter's claim that there is no evidence for dinosaur
endothermy is false. 

Rowe says I am biased in favor of dinosaur endothermy because I argued that
"a) dinosaurs had RT's, and b) RT's are not important to debates about
thermoregulatory physiology". First, I never said that dinosaurs had RT. What
I did say is that my study will refute the "argument that dinosaurs COULD NOT
HAVE HAD RT" (emphasis added). A subtle but important difference. RT can be
shown to be present only by finding preserved examples, otherwise their
presence or absence can only be infered. Second, Mickey, just what do you
want me to do here? You seem to think that my stating both A & B is somehow
unfair and/or biased, but all I am doing is stating the facts as I see them.
Imagine yourself doing a research study in which you find that a) an earlier
study published incorrect data, and b) it turns out that the hypothesis has
little value in the first place? Would you decide to not alert the community
to the incorrect data because you want to publish your conclusion that the
hypothesis is irrelevant, or would you not publish the conclusion because you
want to tag the incorrect data. Or would you do the logical thing and publish
both points, because there is no contradiction inherent to doing so? My being
thorough in no way makes me biased. 

Contra Rowe's hypothesis, I do not use every weapon I can in an attempt to
demonstrate that dinosaurs were tachyaerobic. In the posting I listed a
number of unambiguous characteristics that if observed in dinosaurs would
show they had reptilian energetics. Not my fault that they are not there. 

Jones says that people should refer to the "available information and decide
for themselves". Good idea. For instance, CAREFULLY examine the data behind
all the grand conclusions in Ruben et al's Science paper that Jones
participated in. Note how many birds are used to help come to the conclusion
that there is a fourfold difference between the cross-sectional area of nasal
passages of endotherms and reptiles. Four, FOUR! That's just three big
ratites and one heron. Hardly cutting edge science, indeed it is a grossly
inadequate sample. (This is an example of how the Oregon people prematurely
derive broad conclusions from insufficient data.*) I have measured nasal
passage cross-section in over two dozen birds, plus an interesting giant
mammal. Sorry Jones, your four fold gap does not exist.  As for dinosaurs
having small nasal passages, have you bothered to look up the nose of a large
horned dinosaur? You could park a 58 Buick in one of those spaces. Why did
that not end up on your plot, which included only three, THREE, dinosaurs? I
thought that in science the careful accumulation of large and therefore
significant data sets were the hall mark of good science*. As for the
supposed causal link between RT and metabolism, even K. Nagy - one of the
preeminent field biologists - questions their importance (1995 Science
270:736). 

(* In contrast, my walking and trackway speed data set currently includes a
couple thousand measurements of living and fossil forms. My ilium length data
set includes hundreds of tetrapods living and dead. Now THOSE are data sets.)

Jones also attempts to refute my causal link between limb posture and
metabolism. In doing so he takes a peculiar and not particularly pertinent
trip back to the age of disco, the 70's. He largely correctly explains that
the once common belief that erect limbs are more energy efficient than
sprawling limbs was refuted at that time (however it was Bakker [1972 The
Physiologist 15],  not Taylor [1973], who published the original measurements
 showing lizards will walk a mile for the same energy cost as a mammal of
similar size. Let's give credit where credit is due). But what does this long
resolved issue have to do with the price of tea in China in the 1990s? Jones
did nothing to refute the link I hypothesize between stable sprawling gaits
and slow walking speeds in reptiles, and the faster walking speeds and
consequently higher aerobic exercise capacity probably forced by erect legs.
 

When Jones says that "currently, the only evidence that is functionally
linked to metabolism..........is the presence or absence of (RT)" he is
stating an unsubstantiated opinion. 
The simple fact is that Jones went too far in saying that there is no
evidence for dinosaur endothermy, and he has not shown otherwise. Again this
does not mean the hypothesis that dinosaurs were tachymetabolic has reached
the status of an accepted theory (as per evolution of relativity), but the
hypothesis remains strong. 


Since reading the literature is a good thing, this is a good place to remind
people that if they do not already have the results of the 1994 Dinofest
volume, you should get it ($30.00 made to The Paleontological Soc., c/o Dept
Geol. Sci., Univ. Tennessee, Knoxville TN 37996-1410). Written for the
general public, has many dinosaur papers, including one by Leahy and myself
that outlines new data on dinosaur energetics. 

GSPaul