Re: Dinosaur Were Endotherms (sic)

["Matthew Troutman" <m_troutman@hotmail.com>]

<<I know that I confused the RT issue by erroneously stating that 
someone had written that kiwis had no respiratory turbinates.  I was 
wrong; they havethem, despite their small tube-shaped nasal passages, 
which shows (asGregory S. Paul has pointed out) that RT's can be present 
without the nasals being especially capacious in the region of the RT's.  
This is telling, because it means that the kiwi skull would fail the 
Ruben/Jones/Geist/Hillenius test for RT's, and hence, this known 
endotherm would be judged an ectotherm.  (The RT team conceded that 
pelicans had no
>RT's, but their semi-aquatic habits were taken to be the reason these 
birds
>didn't dehydrate). >>

     I believe GSP was just refering to the anterior nasal passage in 
the kiwi. He stated that Ruben et al. did measure this in their papers 
on turbinates but did not measure the posterior nasal cavity, which can 
hold turbinates. This is incorrect because in the figures in the Ruben 
et al. Science paper and the Complete Dinosaur show the entire nasal 
passage highlighted. If there was a posterior nasal cavity, it would be 
very short because the internal nares are almost always opposite the 
antorbital cavity in dinosaurs. This would preclude RTs. 

>>Furthermore, when the above-named team quantified the nasal passage 
cross-sections of fossilized dinosaur crania to compare with the 
cross-sections of the respiratory turbinate regions of extant endotherms 
and ectotherms, they apparently performed their sections anterior to 
where the RT would most likely be found in life, for the probable site 
of the RT in a dinosaur skull is (correct me if I'm wrong) in the middle 
of an empty cavity farther aft which gives no indication of the 
dimensions of nasal
passages.  As Luis Rey suggests, dinosaurs may have had RT's which 
simply
weren't ossified.  The illustration of the air flow through the nasal
passage of a dromaeosaur skull in the RT article in _The Complete 
Dinosaur_
has come under fire as inaccurate, based on an out-of-date 
restoration.>>

    The position is verible, but the whole passage was narrow according 
to the figures in the papers. See above. 

The dromaeosaur skull in _ The Complete Dinosaur _ was one figured by 
Currie in 1995, hardly old. It may well be inaccurate, though.

Boy, I can feel the flaming getting closer. 


MattTroutman

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