Oxygen Isotopes

Oxygen isotope (gl) values, preserved inside bones are a record of the temperatures at which those bones formed. By extracting and measuring these values scientists can work out how much the body temperatures of animals vary.

Warm-blooded creatures are constantly producing heat and so show very little temperature variation.

Cold-blooded creatures heat up and cool down with their environment and so show large temperature fluctuations within their bones.

What has been found in dinosaur bones?

Some saurichian (gl) dinosaurs (such as Tyrannosaurus Rex)

and some ornithischian (gl) dinosaurs have produced oxygen isotope values which indicate very low levels of temperature variation. If these values are correct, this is very strong evidence for warm-bloodedness within dinosaurs. The low temperature variation is not thought to be indicative of mass homeothermy as there are no large temperature differences between the body and the limbs.

There is currently some concern about alteration of these isotopic values during burial. However, there is agreement that once methods to test for any alteration have been perfected, studies of oxygen isotopes will provide us with valuable information about dinosaur temperature control.