Washington: New technology developed by
US researchers should shed light on whether dinosaurs were
cold-blooded or warm-blooded animals, a study has said.
California Institute of Technology (Caltech)
researchers unveiled what they said was the first method for
direct measurement of the body temperatures of large extinct
vertebrates using analyses of isotopes in animals` bones,
teeth, and eggshells.
The findings were published in the early edition of
the Proceedings of the National Academy of Sciences (PNAS).
"This is not quite like going back in time and
sticking a thermometer up a creature`s back end," said
researcher John Eiler, a geochemistry professor Caltech. "But
To study changes in temperature regulation in extinct
animals requires knowing what their body temperatures once
were. The team`s method looks at the concentrations of two
rare isotopes -- carbon-13 and oxygen-18.
"Heavy isotopes like to bond, or clump together, and
this clumping effect is dependent on temperature," said lead
author Robert Eagle, a Caltech postdoctoral scholar.
"At very hot temperatures, you get a more random
distribution of these isotopes, less clumping. At low
temperatures, you find more clumping."
After proving their method on living elephants and
sharks, the team turned to the extinct.
They examined a 12-million-year-old fossil from a
relative of the rhinoceros, as well as from a cold-blooded
member of the alligator family tree.
"We found we could measure the expected body
temperature of the rhino-like mammal, and could see a
temperature difference between that and the alligator
relative, of about six degrees centigrade," Eagle explained.
"When we look at tooth enamel, for instance, what we
get is a record of the head temperature of the animal when the
tooth grew," Eiler said. But "if you want to know what his
big-toe temperature was two years later, too bad."
With an accurate paleothermometer working, the
researchers want to look further back at body temperatures of
"Before mammals and birds," Eagle said, "we have no
good idea what physiology these ancient creatures had."
Now it is the dinosaurs` turn to get a closer
"We`re looking at eggshells and teeth to see whether
the most conspicuous dinosaur species were warm- or
cold-blooded," Eiler explained.