A new study by scientists at the University of Alaska Fairbanks and the University of Reading questions Bergman’s rule, a scientific principle from the 1800s that states that animals living at higher latitudes with cooler climates tend to be larger than their close relatives living in warmer climates. . .

Fossilized remains show otherwise.

“Our study shows that the evolution of different body sizes in dinosaurs and mammals cannot be reduced to a simple function of latitude or temperature,” said Lauren Wilson, a UAF graduate student and lead author of the paper published in the journal. Nature Communication. . “We found that Bergman’s rule only holds for a subset of homeothermic animals (those that maintain a constant body temperature), and only when you take temperature into account, ignoring all other climate variables. This suggests that Bergman’s ‘rule’ is actually the exception rather than the rule .”

A study of Bergman’s management in dinosaurs and modern species

The research began with a simple question that Wilson discussed with his undergraduate advisor: Does Bergman’s rule apply to dinosaurs?

After evaluating hundreds of data collected from fossils, the answer seemed to be a resounding no.

The data set included the northernmost dinosaurs known to scientists from the Prince Creek Formation in Alaska. They survived frost and snowfall. Despite this, researchers found no noticeable increase in body size for any of the arctic dinosaurs.

The researchers then tried the same assessment on modern mammals and birds, which are descendants of prehistoric mammals and dinosaurs. The results were much the same: Latitude was not a predictor of body size in modern bird and mammal species. There was a slight correlation between body size and temperature in modern birds, but not in prehistoric birds.

The researchers say the study is a good example of how scientists can and should use the fossil record to test modern scientific rules and hypotheses.

“Fossil remains provide a window into very different ecosystems and climates, allowing us to assess the applicability of these ecological rules in a completely new way,” said Jacob Gardner, a PhD student at the University of Reading and another lead author of the paper. .

Pat Druckenmiller, director of the University of Alaska Northern Museum and one of the paper’s authors, said scientific rules should apply to fossil organisms as well as modern organisms.

“You can’t understand modern ecosystems if you ignore their evolutionary origins,” he said. “You have to look at the past to understand how things got to this point today.”