- A new technique analyzes teeth and bones to determine the exact body temperatures of extinct animals.
- Woolly mammoths had body temperatures ranging from 78 to 102 degrees Fahrenheit.
- The researchers are already applying the new method to dinosaurs, with results expected soon.
By studying rare heavy isotopes of carbon and oxygen in bone and teeth remains, scientists determined the body temperature of woolly mammoths and extinct rhinoceroses. Click to enlarge this image.
Mauricio Anton
How hot were woolly mammoths and dinosaurs? A new technique enables scientists to determine the precise body temperatures of these long-gone animals, along with those for other living and extinct species, according to a new study.
The method, described in the latest Proceedings of the National Academy of Sciences, has already revealed the body heat of an extinct rhinoceros (97.8 degrees Fahrenheit), an extinct alligator (86.7 degrees Fahrenheit) and woolly mammoths, which disappeared from most of their range about 10,000 years ago.
Woolly mammoths were a toasty 100 degrees Fahrenheit, which did not surprise the researchers.
"As a large mammal, you would expect it to be warm-blooded and have a body temperature close to 37 degrees Celsius (98.6 degrees Fahrenheit), but it was neat to see that we could measure that as it gives us confidence to start looking at species of unknown physiology," lead author Robert Eagle told Discovery News.
Eagle, a California Institute of Technology geochemist, and his colleagues devised the technique after studying the rare heavy isotopes of carbon and oxygen. These types of isotopes tend to clump together more at low temperatures.
"Therefore, if you can measure the clumping accurately enough, you can work out the temperature at which a mineral precipitated," he explained. "In the case of teeth and bone, this will be the body temperature of the organism."
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Eagle said teeth work best, followed by bone, which can be softer, less dense and more porous, making bone more subject to chemical changes over the years. The scientists can also work with eggshells, but these again tend to not be as well preserved as teeth.
The researchers first tested out the method on modern species for which body temperatures are already known. These animals included a white rhinoceros, an Indian elephant, a Nile crocodile, an American alligator and two sand tiger sharks. Results from the new temperature measuring approach, known as "clumped-isotope analysis of bioapatite," came extremely close in all cases to the animal's actual body warmth.
The scientists then applied the same technique to Late Pleistocene woolly mammoth teeth unearthed at Rhine River and North Sea sites, as well as to fossil teeth for an extinct rhino and alligator that lived during the Miocene Era 25 to 13 million years ago.
Due to the success of these studies, the researchers believe the method could next be used on dinosaur remains.
"The first thing that we could learn is whether dinosaurs had body temperature in the range of 26 to 30 Celsius (78.8 to 86 degrees Fahrenheit), which is the range of temperatures we have seen with our technique for modern and extinct alligators and crocodiles," Eagle said. "If we got temperatures in that range, they would strongly suggest cold-bloodedness."
"If we got temperatures of 96.8 degrees Fahrenheit or more, then it would suggest that dinosaurs were not similar to alligators and crocodiles," he continued, but added that result might not mean dinosaurs were truly warm-blooded. Dinosaurs could have just experienced high body temperatures due to their often large body mass that might have retained more heat.
Herman Pontzer, a Washington University anthropologist, recently used limb measurements of dinosaurs to calculate their energy cost of walking and running, which can help to determine whether or not an animal was warm or cold-blooded.
"Our results provide strong evidence that may dinosaur species were probably warm-blooded," Pontzer said, explaining that dinosaur energy requirements during walking and running would have been too high for a cold-blooded animal to produce.
More precise dinosaur body temperatures will soon be available, since Eagle and his colleagues are already applying their isotope analysis technique to dinosaur remains.
"All I can say is that we are getting interesting temperatures," Eagle said, "but you'll have to watch this space for the result as I don't want to give the game away just yet."
Tags: Alligators and Crocodiles, Dinosaurs, Disappeared, Fossils, Mammoth
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