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Re: respiratory turbinates

In message <199609111623.LAA17785@juliet.ucs.indiana.edu>,
nking.ucs@smtp.usi.edu writes

>This information may be from an article published in Science (v. 273, 30 
>August, 1996, p. 1204-1207), by J. A. Ruben, W. J. Hillenius, N. R. 
>Geist, A. Leitch, T. D. Jones, P. J. Curie, J. R. Horner, and G. Espe 
>III, entitled The Metabolic Status of Some Late Cretaceous Dinosaurs.

One thing the authors did not comment upon is the level of oxygen in the
inspired air. A higher level of ambient oxygen would require a lesser
amount of air to be inhaled, thus a narrower nasal passage would be
compatible with a higher metabolic rate. Several papers suggested that
the level of oxygen in the ambient air was higher (up to 32%) at various
times in the Mesozoic period (for a review see Holland H D, Origins of
breathable air, Nature 1990; 347: 17). I wonder whether this have had a
bearing on the size and structure of the nasal passages of the Mesozoic

Gautam Majumdar                 gautam@majumdar.demon.co.uk