Large dinosaurs could have been active and nocturnal, even without a ?warm-blooded? physiology, according to a report in the Journal of Experimental Biology. Observations of large crocodiles in Australia, by Frank Seebacher and colleagues from the University of Brisbane, show that 1,000-kilogram crocodiles maintain stable, steady internal body temperatures much more easily than smaller crocodiles. Extrapolating these results to hypothetical reptiles ten times as massive, one would find even greater independence of body temperature from external temperature fluctuations.
So much is expected. A new finding is that core temperature actually rises with mass. Seebacher and colleagues find that as crocodiles get larger, with a greater internal volume in relation to their surface area, it gets harder for them to lose heat by convection from the surface. This results in a net rise in core temperature. So, rather than worrying about getting too cold to be active, large reptiles - and possibly dinosaurs - would have had problems of overheating.
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