Paleontologists have long argued over the question of dinosaur metabolism – whether it was hot, like modern birds and mammals, or similar to the slower metabolism of modern reptiles. In a surprise, the answer seems to be both.
“While we assumed most dinosaurs were warm-blooded, there was no way to measure basic metabolic abilities,” said Jasmina Wiemann, a paleontologist at the California Institute of Technology. With no dinosaurs available, she said, paleontologists grappling with questions about prehistoric metabolism — whether a hot-blooded or cold-blooded monster, for example — had to rely on indirect evidence, such as isotopic evidence or bone segment growth rates.
Now, Dr. Weiman and his colleagues have developed a new method to directly measure the metabolic rate of extinct animals. their conclusions, Published Wednesday in Nature, claimed that many dinosaurs as well as their winged relatives, the pterosaurs, were warm-blooded than their ancestors. But in a twist, the research also indicates that some herbivorous dinosaurs spent tens of millions of years developing a cold-blooded metabolism like that of modern and ancient reptiles.
The team analyzed more than 50 extinct and modern vertebrates from the collections of the Yale Peabody Museum of Natural History, including mammals, lizards, birds and 11 different non-bird dinosaurs. Using laser spectroscopy, they identified a specific molecular marker of metabolic stress in modern fossils and bones – an indicator that is directly correlated to the amount of oxygen the animal breathes. This, in turn, is a direct indication of metabolism.