Birds and mammals independently developed the highest metabolic rates among living animals. Their metabolism generates heat that enables active thermoregulation, forming the ecological niches they can occupy and their adaptability to environmental changes. However, there is no proxy that allows the direct reconstruction of metabolic rates from fossils.
A new study by Yalea Scientists shed light on dinosaur metabolism by identifying molecular markers for metabolic stress in skeletal material. They found that the earliest dinosaurs and pterosaurs had exceptionally high metabolic rates and were warm-blooded animals.
Lead author Jasmina Wiemann, a former Yale paleontologist who now works at CalTech, said: “While modern ecologists tend to emphasize the importance of metabolism in ensuring that animals survive environmental disturbances, we have shown that metabolism is not why birds were the only group of dinosaurs to survive the mass extinction at the end of the century Cretaceous Age† Many dinosaurs with metabolisms as efficient as those of modern birds have become extinct.”
As mentioned above, scientists identified molecular markers of metabolic stress found in skeletal material in modern animals and long-extinct species. The biomarkers provide direct insight into the metabolism of old animals.
Senior author Derek Briggs said: “The interactions of animals and the role they play in an ecological community is reflected in their metabolism. Metabolism reflects how much oxygen an animal breathes in proportion to its body mass. Excess heat is released as a byproduct of oxygen respiration — which determines whether an animal is warm-blooded and can maintain a constant body temperature or is cold-blooded and dependent on the outside temperature of its environment for survival.”
“In recent years, new research has been conducted into dinosaurs has transformed their image, shifting focus from slow reptilian giants to agile predators, but the real metabolic and thermoregulatory capabilities of dinosaurs are under debate.”
Scientists analyzed more than 50 fossil and modern vertebrates from the collections of the Yale Peabody Museum of Natural History. They then used laser microspectroscopy techniques such as Raman and Fourier transform infrared spectroscopy to capture biomarkers in modern and fossil bones that respond to laser light.
Scientists showed that many early dinosaurs had a metabolism similar to that of modern birds.
Briggs said, “Dinosaurs were remarkably fast and agile animals with energy levels similar to those of modern warm-blooded animals and, most notably, they developed the exceptional metabolism of modern birds long before active flight.”
Over time, metabolism was found to decline in all major groups of ornithischian dinosaurs, including Stegosaurus and Triceratops.
Wiemann said† “Such low metabolic rates imply that these dinosaurs depended on thermoregulation of behaviors, such as sunbathing and seasonal migration to warmer climates. It appears that warm-bloodedness evolved several times independently, in mammals, in marine reptiles such as the Plesiosaurus, and in ornithodirans, the group.” which includes dinosaurs and pterosaurs.”
Wiemann said she and her colleagues are hopeful that their new, biomolecular approach to analyzing fossils will help paleontologists and zoologists.
“Our aim is to provide a comprehensive picture of how animal physiology responded to past environmental and ecological changes and to contribute to the lessons of the past that will guide future strategies for preserving biodiversity across times. from global climate change†
- Wiemann, J., Menendez, I., Crawford, JM, et al. Fossil biomolecules reveal an avian metabolism in the ancestral dinosaur. Nature (2022). DOI: 10.1038/s41586-022-04770-6
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