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Re: RUBEN ET AL ON R.T.



I have been musing over some recent discussions, and, in my usual 
Socratic way, pose some rhetorical questions for consideration.

I'll key off Darren Naish's comments (9/13/96; 9:53a):

[snip]

>However, the case for non-tachymetabolic dinosaurs is looking better 
>and better. If this bothers you, learn more about extant reptiles. Did
>a pile of good for me.

Remember "How big is big?"  The following question can be classified in 
the same taxonomic (generic?) group:  "How tachymetabolic is 
tachymetabolic?"

I wonder how dinosaurs would have been originally classified if they were 
extant?  

Has anyone ever suggested that we can learn about the metabolism of birds 
by studying extant reptiles?

Finally, the claim that oxygen levels were 30%+ in the Cretaceous has 
been soundly criticized in very recent literature.  Sorry, I don't have 
references handy.  Just something to be aware of--don't assume those 
claims to be correct.  The original claims were based upon certain 
assumptions about the significance of geochemical data (from amber???) 
with respect to ancient oxygen levels.  Those assumptions may not be 
true.

Should we also beware of assumptions about the significance of the 
presence or absence of respiratory turbinates for assessing metabolic 
rates of extinct animals, especially since there are exceptions to the 
correlation in extant animals that Ruben et al pointed out?


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Norman R. King                                       tel:  (812) 464-1794
Department of Geosciences                            fax:  (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712                      e-mail:  nking.ucs@smtp.usi.edu