The 180-million-year-old secret of evolution: Scientists discover potential origin of the first ‘warm-blooded’ dinosaurs

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Dromaeosaurus

Recent research indicates that some dinosaurs may have evolved the ability to regulate their body temperature internally during the Early Jurassic period, allowing them to adapt to colder climates and survive environmental challenges. The artist’s impression shows a dromaeosaur, a type of feathered theropod, in the snow. This group of dinosaurs is popularly known as a bird of prey. That is a well-known dromaeosaur Velociraptorportrayed in the film Jurassic Park. Credit: Davide Bonadonna/Universidade de Vigo/UCL

A new study led by researchers from UCL and the University of Vigo suggests that the ability to regulate body temperature, a trait common to all modern mammals and birds, may have first evolved in certain dinosaurs in the early 1900s Jura- period, about 180 million years ago.

A new study led by researchers from UCL and the University of Vigo suggests that the ability to regulate body temperature, a trait common to all mammals and birds, first evolved in some dinosaurs during the Early Jurassic period, about 180 million years ago.

Early 20se For centuries, dinosaurs were considered slow-moving, “cold-blooded” animals, like modern reptiles, that relied on the sun’s heat to regulate their temperature. Newer discoveries indicate that some types of dinosaurs were likely able to generate their own body heat, but when this adaptation occurred is unknown.

Research methods and findings

The new study, published in the journal Current biologylooked at the distribution of dinosaurs across different climates on Earth throughout the world Mesozoic Era (the dinosaur era that lasted 230 to 66 million years ago), based on 1,000 fossils, climate models and the geography of the period, and the evolutionary trees of dinosaurs.

The research team found that two of the three major groups of dinosaurs, theropods (such as T. rex And Velociraptor) and ornithischians (including relatives of the herbivores Stegosaurus And Triceratops), moved to colder climates during the Early Jurassic, indicating that they may have developed endothermy (the ability to generate heat internally) at that time. In contrast, sauropods, the other main group to which the Brontosaurus and the Diplodocusheld in warmer areas of the planet.

Previous research has found traits associated with warm-bloodedness in ornithischians and theropods, which are known to have feathers, or proto-feathers, that insulate internal heat.

Evolutionary implications

First author Dr. Alfio Alessandro Chiarenza, from UCL Earth Sciences, said: “Our analyzes show that different climate preferences emerged among the main dinosaur groups around the time of the Jenkyns event 183 million years ago, when intense volcanic activity led to global warming and climate change. extinction of plant groups.

“Many new dinosaur groups emerged at that time. The adoption of endothermy, perhaps a result of this environmental crisis, may have allowed theropods and ornithischians to thrive in colder environments, allowing them to be highly active and maintain their activities for longer periods, develop and grow more quickly and produce more offspring could produce.

Co-author Dr. Sara Varela, from Universidade de Vigo, Spain, said: “Theropods also include birds and our study suggests that birds’ unique temperature regulation may have its origins in this early Jurassic period. In contrast, sauropods, which resided in warmer climates, grew to gigantic size around this time – another possible adaptation due to environmental pressures. Their smaller surface area to volume ratio would have caused these larger creatures to lose heat at a slower rate, allowing them to remain active longer.”

Broader implications of the research

In the paper, the researchers also explored whether sauropods may have stayed at lower latitudes to eat richer foliage unavailable in colder polar regions. Instead, they found that sauropods appeared to thrive in dry, savannah-like environments, supporting the idea that their restriction to warmer climates was more related to higher temperatures and subsequently a more cold-blooded physiology. During that time, the polar regions were warmer, with abundant vegetation.

The Jenkyns event occurred after lava and volcanic gases erupted from long fissures in the Earth’s surface, covering large parts of the planet.

Co-author Dr. Juan L. Cantalapiedra, from the Museo Nacional de Ciencias Naturales, Madrid, Spain, said: “This research suggests a close link between climate and the way dinosaurs evolved. It sheds new light on how birds may have inherited a unique biological trait from dinosaur ancestors and the different ways in which dinosaurs adapted to complex and long-term environmental changes.”

Reference: “Early Jurassic origins of avian endothermy and thermophysiological diversity in dinosaurs” by Alfio Alessandro Chiarenza, Juan L. Cantalapiedra, Lewis A. Jones, Sara Gamboa, Sofía Galván, Alexander J. Farnsworth, Paul J. Valdes, Graciela Sotelo and Sara Varela, May 15, 2024, Current biology.
DOI: 10.1016/j.cub.2024.04.051

The study was funded by the European Research Council, the Royal Society, the Natural Environment Research Council and the Spanish Ministry of Research.

The study involved researchers from UCL, the University of Vigo, the University of Bristoland the Museo Nacional de Ciencias Naturales in Madrid, and received funding from the European Research Council, the Spanish Ministry of Research, the Natural Environment Research Council and the Royal Society.

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