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Dinosaurs May Have Self-Regulated Their Body Temperature

The high metabolic rates of dinosaurs suggest that they were endotherms

by Complutense University of Madrid
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Dinosaurs and pterosaurs had high metabolic rates, suggesting they were endothermic, i.e., capable of self-regulating their bodily temperature, according to an international study published in Nature, led by the University of Yale, in which the Complutense University of Madrid (UCM) participated.

“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,” notes Jasmina Wiemann, researcher at the University of Yale, which led this study.

For the first time, the research makes use of an index which allows a direct assessment of the metabolic capacities of amniotes (mammals, birds, reptiles, and extinct groups like dinosaurs and pterosaurs), both existing and extinct, as it uses metabolic markets that can be found in fossil form.

The production of heat in endotherms is due to their metabolism, which burns fat and sugars. This process releases energy (heat), but also other products.

Iris Menéndez, a paleontologist at UCM, explains the method used: “Some of the molecules which are produced can fossilize, and this is opening up a new field in paleontology, in which geochemists such as Jasmina can obtain information from original tissues. In this case, we measure the signs left by high metabolic rates in the molecules.”

Dismantling the extinction hypothesis

Mammals and birds are now considered endotherms, while reptiles do not have this capacity to self-regulate their temperature metabolically.

For many years, the belief that dinosaurs were ectotherms was used as an explanation for their extinction at the end of the Cretaceous Age, as they would not have had the capacity to regulate their bodily temperature to combat the temperature fluctuations of their environment.

“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,” concludes Menéndez.

As well as the use of this work to discover the possible causes of the extinction or survival of species, Menéndez points to another:

“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.”

- This press release was provided by the Complutense University of Madrid