James Lee

Despite the outsized role dinosaurs have played in film and our imaginations, their physiology has long eluded scientists. 

Earlier this year, a Yale group conducted a study finding groups of dinosaurs were warm-blooded, providing a new basis for the understanding of dinosaur biology. The researchers studied three lineages of dinosaurs — sauropods, ornithischia and therapods —  in terms of their internal body temperature compared to the external environmental temperature. The lead author of the paper was Robin Dawson, who conducted the research as a doctoral student in geology and geophysics at Yale, along with Yale paleontologist Pincelli Hull and former Yale researchers Daniel Field and Hagit Affek.

“For as long as we were studying dinosaurs, we were fascinated by them,” said Dawson. “There’s been this question of how similar or different are they to living reptiles in terms of how they maintain their body heat.” 

The study was first inspired by a paper attempting to research the temperature of dinosaurs by analyzing teeth, Dawson said. The group chose to use eggshells, however, as they form within the body of a female dinosaur and would therefore be “more representative of the core body temperature.” In the study, they applied a technique called clumped isotope paleothermometry, first developed for paleoclimate studies, to analyze the eggshells. 

The group additionally considered the body temperature of the dinosaurs in relation to the external environmental temperature when drawing their conclusions. The comparison allowed them to more definitively state that dinosaurs were likely able to raise their body temperature using their metabolism, as opposed to simply having warmer temperatures as a result of being in a hot environment. This ability to utilize metabolism to control internal body temperature, Dawson stated, is an ancestral trait and “something we can tie back to the common ancestor of all these three groups of dinosaurs.” 

“My research usually uses the same geochemical methods to study climate change, but these methods give us the tool to ask questions about other temperatures too,” Affek wrote in an email to the News. “The idea to understand body temperatures through comparison with environmental temperature is of course related to my climate research.” 

The study additionally provides insight into the evolution of the physiology of modern birds and their specialized biological features.

“We discovered that all three of those major lineages of dinosaurs exhibited internal body temperatures that fall within the range of variation of living birds, suggesting that what we think of as the specialized warm-bloodedness of living birds may actually be a truly ancient feature,” said Field. 

There are still many questions about these captivating creatures left to answer. In the future, Dawson hopes to “look at more diverse groups” and go “further back in the evolutionary tree to see how far back this capability goes.”

Still, Affek wrote, “Like most curiosity driven basic research, there are no clear direct implications. However, if a study like this one would inspire students to be interested in geochemistry, we have done our job.” 

The Great Hall at the Peabody, home to many of the museum’s dinosaur fossils, was opened in the 1930s.