Caltech Scientists Measure Dinosaur Body Temp 51
damn_registrars writes "Using rare isotope ratios, a geology team at CalTech has determined body temperatures of sauropod dinosaurs. Their work finds temperatures that are roughly in line with modern mammals for body temperature. However, as the authors point out, this does not on its own confirm dinosaurs to be entirely warm-blooded, as they may have kept these temperatures by sheer mass. The peer-reviewed paper is available online in PNAS. You can also get the article free through pubmed."
metabolic vs. thermoregulated heat (Score:5, Interesting)
The point about body mass, if it's not clear, is that metabolism produces huge amounts of heat. When we digest food, about 50% of the energy that's released in converting complex molecules to carbon dioxide and water is released as heat. A huge animal can keep warm just from that. Mammals and birds maintain their temperature in a very narrow range. However, it's more complicated than just that would indicate: hibernating mammals (and one species of bird that hibernates) allow their temperature to fluctuate with the outside temperature. Likewise, there are reptiles that do some things to reduce their temperature variation, by seeking sunlight or shade, which is a type of active regulation. One current theory about dinosaurs and the evolution of feathers is that they showed up primarily as a thermoregulation system, providing insulation (particularly in rain) but allowing the animals to fluff their feathers to increase temperature losses to again actively thermoregulate.