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Re: Physiological Adaptations of the Dinosauria (long)






to: "Rob Gay" from: Waylon D. Rowley


Allow me to interject for a moment here:
From what I have seen (pictures and drawings) of _D. sinensis_, the crests are apx. the same size as that of _D. wetherilli_ (a little >bigger, but negligible). However, they appear to be much thicker than >_D. wetherilli_, and I would think that you would want thin vanes if >you were going to be using this structure as a radiator. But if we were >going to discuss crest vs. total skull size, I would think that >_Syntarsus kayentakatae_ would have the largest proprtional crest, >being apx. 40% of the length and 21% of the height of the skull, plus >having an antobrital fenestra almost as long and twice as tall. And, >this is almost contra your argument, but most coelophysoids have >huge< >antorbital fenestrae, covering in some cases almost 45% of the length >of the skull.

Unless you know something that I don't, the specimens of D. wetherilli
were preserved *without* crests, and they used D. breedorum (which does have crests) to fill in the gaps in our knowledge on D. wetherilli's crest morphology. Check out this link: http://dinosauricon.com/images/dilophosaurus-am.html
Since I lack any knowledge of D. breedorums crest height, length, and width, I opted for ?D. sinensis for which I have seen pictures of at least.





In coelophysoids that had crests, most of the crest was composed of the lacrimal, or even a seprate bone, as posited by Welles (1984), so
positioning might be questionable for this function.

In that case, we need to know whether this "separate bone" has foramina for the superior nasal artery.



This is a hypothetical _Eucoelophysis_ that you speak of, right? Because _E. baldwini_ wasn't similarly-sized.

I'm talking about an E. baldwini that has been scaled up to ?D. sinensis size.



Both of the areas mentioned here are what you propose
for heat exchangers, so you have no neutral ground. You'd also need to take a sample from some place like the illium or the scapula to see >if there was a difference.

Good point. Unfortunately, I simply don't have the money nor equipment to do a study like this....so i'm going to leave it to the hands of more prestigious paleontologists (assuming they'd want to test my hypothesis in the first place.)
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