Fossilized eggs offer clues to dinosaur body temperatures

Science : Dinosaurs were once thought to be cold-blooded like reptiles but as the close relationship between dinosaurs and birds has been studied, many paleontologists have come to believe that dinosaurs were actually warm-blooded. Some researchers have attempted to measure body temperatures by comparing the ratios of and bonds between carbon and oxygen isotopes (which are determined by the temperature of the original material) in fossils, but the evidence hasn’t been conclusive. Now Robert Eagle of UCLA and his colleagues have examined eggshells of two types of dinosaurs. They chose eggs because they form inside the body and would provide evidence of the temperature during a dinosaur’s ovulation. The eggs also might have originally been similar to modern chicken eggs, with a structure that was 97% calcium carbonate, which would make it easy to determine how well-preserved the eggs were. Of the 32 eggshells Eagle’s team analyzed, only 6 were considered to be in good enough condition for accurate measurements. The analysis revealed that the three eggs from titanosaurids were laid by dinosaurs with body temperatures around 37.6 °C, in line with previous work. The other three eggs, from oviraptorids, suggest a parent body temperature of 31.9 °C.