You know those enormous, slow-moving, long-tailed, tall-tree-munching dinosaurs that you imagine slogging in the background while T. rex wreaks havoc in the ancient world? Well, all that 110 tons of flesh (220,000 pounds, or the weight of about 60 cars) had about the same internal temperature as your own body does right now. Paleontologists have long embraced the idea of warm-blooded dinosaurs, but estimating exact temperatures has (of course) been a challenge. But recently, a new method of studying chemical bonds in fossils to determine the body temperatures of prehistoric creatures led Robert Eagle of California Institute of Technology to the conclusion that although massive, sauropod dinosaurs had approximately the same body temperatures as humans. John Eiler, Eagle’s postdoctoral advisor who developed the method, discovered that a specific kind of bond between carbon and oxygen in growing bone forms more often at lower temperatures than at higher temperatures. Eagle applied this method to the teeth of 150-million-year-old sauropods from Tanzania, Oklahoma, and Wyoming, and found their internal temperatures to fall between 36 and 38 degrees Celsius, right around the normal human body temperature of 37 degrees. Because sauropods were so huge, paleontological growth studies estimated their body temperatures 3-7 degrees warmer than Eagle’s estimate. But because the new method shows otherwise, Eagle and colleagues have proposed that sauropods must have had cooling mechanisms to keep their internal temperature hovering around 37 degrees. Perhaps sauropods had internal cooling sacs, or their long appendages provided surface area for ventilation. Or maybe, like us, they just headed to a shady spot when they were feeling a little too warm! Next steps in the Eiler-Eagle laboratory are similar analyses on more sauropods, other dinosaurs, as well as mammals and birds, in the hope of discovering the very roots of the evolution of warm-bloodedness.

Read more at ScienceNews.org.

The published study on sauropods can be found in a July 2012 issue of the journal Science.

Published On: April 26, 2012

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