Dinosaurs needed to be cold enough for warm-bloodedness to matter

Dinosaurs were once assumed to be cold-blooded or ectothermic, an idea that makes sense since they were reptiles. While scientists have previously discovered evidence of dinosaur species that were warm-blooded, what could have led to this adaptation remained unknown. A team of researchers now believe that dinosaurs, which already had some ability to tolerate cold, evolved endothermic, or warm-blooded, adaptations when they migrated to areas with colder temperatures. They also believe they have found a possible reason for the flight.

Using the Mesozoic fossil record, evolutionary trees, climate models, and geography, as well as taking into account a dramatic climate change event that caused global warming, the team found that theropods (predators and ancestors of birds such as Velociraptor and Tyrannosaurus rex) and ornithischians (such as Triceratops and Stegosaurus) must have made its way to cold regions during the Early Jurassic. Low temperatures are thought to have led to the selection of species that are partially adapted to internal heat.

“The early invasion of great niches… [suggests] An early investigation of isothermal (possibly endothermic) physiology in [certain species]The researchers said in a study published by the British newspaper “Daily Mail”: “Which enabled them to colonize and continue even at extreme latitudes since the Early Jurassic period.” Stady Recently published in Current Biology.

Hot real estate

During the Mesozoic Era, which lasted from 230 to 66 million years ago, primitive dinosaurs known as tyrannosaurids began to diversify into hot, dry climates. Early sauropods, ornithischians, and theropods all tended to survive in these areas.

Sauropods (such as Brontosaurus and Diplodocus) would become the only dinosaur groups to be thermophilic – the fossil record shows that sauropods tended to survive in warmer regions, even if there was less food. This indicates the need for sunlight and heat associated with external heat. They may have been able to survive at colder temperatures, but were not adapted enough to survive for long, according to one hypothesis.

It’s also possible that living in colder regions meant a lot of competition with other types of dinosaurs, as theropods and ornithischians ended up moving to these cooler regions.

Almost the end of the world

Far from environmental opportunities that may have attracted dinosaurs to colder regions, they were likely kept away from warmer regions. About 183 million years ago, there was a disruption in the carbon cycle, coupled with intense volcanic activity that spewed out massive amounts of methane, sulfur dioxide and mercury. Life on Earth suffered from scorching heat, acid rain, and forest fires. known as Early Jurassic Jenkins EventResearchers now believe that these disturbances pushed theropod and ornithischian dinosaurs into colder climates because temperatures in warmer regions exceeded the ideal temperatures for their survival.

Theropods and ornithischians that survived the impacts of the Jenkins event may have had a major adaptation to cold climates; It is now believed that many dinosaurs from these groups were covered with feathers. Feathers could be used to trap and release heat, which allowed feathered dinosaurs to regulate their body temperature in more diverse climates. Modern birds use their feathers in the same way.

Dinosaur species with feathers or special structures that improved heat management could have been endothermic, meaning they were able to maintain their body temperature through metabolic or even endothermic activity.

Aside from dinosaurs that migrated to high latitudes and adapted to lower temperatures, endotherms may have given rise to new species and lineages of dinosaurs. It may have contributed to the emergence of Avialae, the clade that includes birds – the only actual dinosaurs still extant – dating back to their earliest ancestors.

“[Our findings] “It provides new insights into the origin of avian endotherms, suggesting that this evolutionary path within theropods… may have begun in the latest Early Jurassic period,” the researchers said in the same article. Stady.

This is really something to think about next time a bird flies by.

Current Biology, 2024. DOI: 10.1016/j.cub.2024.04.051