|Caltech Geochemists Rob Eagle (L) and John Eiler|
The method used for this analysis is called a clumped isotope technique. The concentrations of the isotopes carbon-13 and oxygen-18 in bioapatite, a mineral found in teeth and bone. How often these isotopes bond with each other (clump, if you will) hinges on the temperature. The lower the temperature the more the isotopes tend to bond with each other. So, the researchers measured how these isotopes clumped together to determine the environmental (in this instance the internal condition of the dinosaur) temperature. At least, the temperature of the tooth.
The study allowed the researchers to estimate the temperature of Brachiosaurus to 100.8 degrees Fahrenheit and the temperature of Camarasaurus to 96.3 degrees Fahrenheit. This is warmer than living and extinct reptile species (like crocodiles) but is cooler than birds both of which are believed to be modern descendants of the dinosaurs. According to the researchers the measurements are accurate to within one or two degrees.
|Drilling a Camarasaurus tooth|
The study led the Caltech researchers to conclude that dinosaurs were warm blooded (have an internal mechanism to moderate body temperature), but they warn that the issue is actually more complicated that just temperature readings. Even if the creatures were cold blooded and relied on their environment for warmth, they still could have had very warm bodies. Unfortunately knowing the temperature of the teeth don't answer all of the remaining questions about dinosaur temperature.
The scientists hope to expand upon this study to include analysis of the teeth of other species of extinct vertebrates, in addition to determining the internal temperatures of small and young dinosaurs that may reveal more about how temperature affected the way these creatures lived. The research paper was published in ScienceExpress. More information (from a press release) is available from Caltech and in the following video (which were both used as sources for this post.)
(All media courtesy of Caltech)