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Re: Even more on dino metabolics
At 6:56 AM 9/17/95, Paul Willis wrote:
>>Something I forgot in my discussion of dinosaur air-sac systems, and Ruben's
>>concern about the lack of large sternal plates in dinosaurs. Of course, we
>>now know that some advanced theropods had sternal plates as large as those of
>>many birds. In fact, the theropods' sternals are sometimes larger than those
>>of flightless birds! In addition, theropods and (as we now know) sauropods
>>had gastralia that may have been used to help ventilate abdominal air-sacs.
>Don't stop there Greg. Crocs and plesiosaurs also had (or have) gastralia.
>Proof-positive that they also had (have) air-sacs?
Even better, snakes also possess expansive abdominal ribs, as do
other lepidosaurs. Guess nothing is ectothermic anymore. Theropods
possessing a sternum/ body size ratio that is roughly comparable to modern
birds?? None so far. Since it is the sternum that helps to ventilate
avian lungs, I guess the small sternal plates of dinosaurs wouldn't be such
good evidence after all.
Jason J. Head
V.P. graduate student
Dept. of Geological Sciences
Southern Methodist University
Dallas, Tx. 75275