Carbon-13 and Oxygen-18 in Dinosaur, Crocodile, and Bird Eggshells Indicate Environmental Conditions

We have gathered, from the nests of dinosaurs, and living and fossil birds, some evidence of the environment in which these creatures lived. However, our isotope determinations suggest it will be impossible to resolve the problem as to whether the dinosaurs were warm- or cold-blooded from the oxygen and carbon isotope content of their shells.