For most of the 20th century, the image of a lumbering, cold-blooded dinosaur dominated our understanding of these prehistoric giants. Recent discoveries, however, have challenged this view, suggesting some dinosaurs possessed the ability to regulate their body temperature, a trait known as endothermy. A new study published in Current Biology sheds light on this possibility, proposing that the first warm-blooded dinosaurs might have emerged much earlier than previously thought – around 180 million years ago.
This research, led by a team from UCL and the University of Vigo, focused on the diversification of dinosaurs across various climates throughout the Mesozoic Era, the age of dinosaurs spanning from 230 to 66 million years ago. By analyzing over 1,000 fossils, climate models, geographical data, and dinosaur evolutionary trees, the researchers observed a shift in dinosaur climate preferences around 183 million years ago. This period coincided with the Jenkyns Event, a major volcanic eruption that triggered global warming and mass extinctions among plant life. Interestingly, the study suggests that this period also saw the emergence of new dinosaur groups, potentially with varying levels of endothermy.
Generating their heat would have provided dinosaurs with a significant evolutionary advantage. Endothermy allows animals to maintain a stable body temperature regardless of the external environment, enabling them to stay active in cooler climates and potentially reach higher activity levels. This characteristic is crucial for birds, the modern-day descendants of theropod dinosaurs, known for their energetic lifestyles and soaring flight capabilities.
While the exact timing of the endothermic shift in dinosaurs remains debated, this study offers a compelling argument for its early emergence. The diversification of dinosaur lineages around the Jenkyns Event suggests that some dinosaurs may have developed endothermy or improved their internal temperature regulation as an adaptation to the changing climate. This ability could have played a key role in their survival and subsequent diversification, eventually leading to the rise of birds.
The findings of this research not only challenge our traditional understanding of dinosaur physiology but also raise intriguing questions about the evolution of endothermy. Did all dinosaur lineages develop this trait, or was it specific to certain groups? How did endothermy influence dinosaur behavior and activity levels? Further exploration of fossil evidence and developing new analytical techniques may answer these questions, offering a clearer picture of the warm-blooded world of dinosaurs.