A new study led by researchers from UCL and the University of Vigo suggests that the ability to regulate body temperature, a trait shared by all modern mammals and birds, may have first evolved in some dinosaurs at the beginning of the Jurassic period, around 180 million BC. Years ago.

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

In the early 20th century, dinosaurs were thought to be slow, “cold-blooded” animals, like modern reptiles, that relied on the heat of the sun to regulate their temperature. New discoveries show that some dinosaur species were able to generate their own body heat, but it is not known when this adaptation occurred.

Research methods and results

New research published in the journal Current Biology He examined the distribution of dinosaurs in different climates on Earth during the Mesozoic period (the era of the dinosaurs was 230 to 66 million years ago), based on 1,000 fossils, the climate patterns and geography of the period, and dinosaur evolution trees.

The research team found that two of the three main dinosaur groups, theropods (e.g. t. rex And velociraptor ) and ornithischians (including relatives of herbivores) stegosaurus And triceratops ), moved to a colder climate in the early Jurassic period, suggesting that they may have developed endothermy (the ability to generate heat internally) during this period. In contrast, another large group, sauropods, brontosaurus And diplodocusIt is kept in warmer parts of the planet.

Previous studies have identified traits associated with warm-bloodedness among ornithochians and theropods; some were known to have feathers or protofeathers that insulated internal heat.

Evolutionary consequences

Lead author Dr. from UCL Earth Sciences. Alfio Alessandro Chiarenza said: “Our analysis shows that different climate preferences emerged among the main dinosaur groups during the Jenkins Event, 183 million years ago, when intense volcanic activity led to global warming and plant extinctions.” communities.

“Many new groups of dinosaurs emerged during this time. Perhaps the adoption of endothermy as a result of this ecological crisis allowed theropods and ornithischians to thrive in colder environments, to be very active and to maintain their activity for longer periods of time, to develop and grow faster and to produce more offspring.” “It may have enabled them to produce

Co-author Dr. from the University of Vigo, Spain. Sara Varela said: ‘Theropods also include birds, and our study suggests that birds’ unique temperature regulation may have originated in the early Jurassic period. On the other hand, sauropods that remained in warmer climates grew to gigantic sizes during this period; Another possible adaptation resulting from environmental pressures. “The smaller surface area to volume ratio means these larger creatures will lose heat at a slower rate, allowing them to remain active for longer periods of time.”

Wider implications of the study

In the paper, the researchers also investigated whether sauropods might have stayed at lower latitudes to eat more abundant vegetation not available in colder polar regions. Instead, they found that sauropods were able to thrive in arid, savannah-like environments; This supported the idea that their restriction to warm climates was related to higher temperatures rather than cold-blooded physiology. At that time, the polar regions were warmer and had abundant vegetation.

The Jenkyns event occurred when lava and volcanic gases, covering large areas of the planet, erupted from long cracks in the Earth’s surface.

Co-author Dr. from the National Museum of Natural Sciences in Madrid, Spain. Juan L. Cantalapiedra said: “This study shows a strong link between climate and the evolution of dinosaurs. It provides new insight into how birds may have inherited a unique biological trait from their dinosaur ancestors, as well as the different ways dinosaurs adapted to complex and long-term environmental changes.” sheds light.”