Mammals and birds are endotherms – that is, organisms capable of self-regulating their body temperature. Reptiles, on the other hand, are ectotherms since they do not have this ability of self-regulating their temperature metabolically and must rely more heavily on environmental factors to survive.
For many years, scientists believed that the dinosaurs were ectotherm too – a feature which was often used to explain their extinction at the end of the Cretaceous Period, as they would not have had the capacity to regulate their body temperature to combat the temperature fluctuations of their environment. However, a new study led by Yale University has found that dinosaurs and pterosaurs had high metabolic rates, suggesting that they were in fact endothermic.
“This study demonstrates that dinosaurs were real endotherms, and refutes previous ideas that they had an intermediate condition (mesothermia) between ectotherms and endotherms, or that they could maintain their bodily temperature constant thanks to their large bodies, given that there are small dinosaurs with high metabolic rates,” said study lead author Jasmina Wiemann, a molecular paleobiologist at Yale.
Dr. Wiemann and her colleagues used metabolic markers found in fossils to assess the metabolic capacities of dinosaurs. The analysis revealed that these creatures had high metabolic rates, which helped them regulate their body temperature in order to adapt to environmental fluctuations. These findings refute the hypothesis that dinosaurs’ extinction was caused by their incapacity to do this.
“According to the results of this research, being an endotherm is not an advantage in the case of mass extinctions, and we will have to look for causes other than the metabolism they had, which was similar to that of mammals and birds which did survive,” said study co-author Iris Menéndez, a paleontologist at the Complutense University of Madrid.
“This study provides us with knowledge about extinct species. Sometimes we have the idea that there are not many discoveries still to be made, but the reality is that many studies in recent decades are continuing to change the ideas we had about what some species were like, and help us understand life in the past better,” she concluded.
The study is published in the journal Nature.