A study on dinosaurs refutes a current theory from the 19th century

April 8 () –

Bergmann's rulewhich has established since the 19th century that animals in colder climates of high latitudes they tend to be larger than their relatives from warmer climates, has been refuted.

A new study, led by scientists at the University of Alaska Fairbanks (UAF) and the University of Reading, determines that the fossil record shows the opposite.

“Our study shows that the evolution of various body sizes in dinosaurs and mammals cannot be reduced to a simple function of latitude or temperature,” Lauren Wilson, a UAF graduate student and lead author of a paper, said in a statement. published in the magazine Nature Communications. “We discovered that Bergmann's ruleIt is only applicable to a subset of homeothermic animals (those that maintain stable body temperatures), and only when temperature is considered, ignoring all other climatic variables. This suggests that Bergmann's 'rule' is really the exception and not the rule.”

The study began as a simple question that Wilson discussed with his college advisor: Does Bergmann's rule apply to dinosaurs?

After evaluating hundreds of data points drawn from the fossil record, the answer seemed like a resounding “no.”

The data set included the northernmost dinosaurs known to scientists, those from the Prince Creek Formation of Alaska. They experienced freezing temperatures and snowfall. Despite this, the researchers found no notable increase in body size in any of the Arctic dinosaurs.

Next, the researchers attempted the same assessment with modern mammals and birds, descendants of prehistoric mammals and dinosaurs. The results were largely the same: latitude did not predict body size in modern bird and mammal species. There was a small relationship between the body size of modern birds and temperature, but the same did not happen with prehistoric birds.

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

“The fossil record provides a window into completely different ecosystems and climatic conditions, allowing us to evaluate the applicability of these ecological rules in a completely new way“said Jacob Gardner, a postdoctoral researcher at the University of Reading and another lead author of the study.

Scientific rules should apply to fossil organisms the same way they apply to modern organisms, said Pat Druckenmiller, director of the Museum of the North at the University of Alaska and one of the paper's co-authors.

“Modern ecosystems cannot be understood if their evolutionary roots are ignored.” he said. “You have to look to the past to understand how things came to be what they are today.”