WERE DINOSAURS WARM OR COLD BLOODED?

New research has heated up the debate over whether dinosaurs were ectothermic (cold-blooded) or endothermic (warm-blooded like us). The topic is addressed in this week's Johns Hopkins News-Letter and a recent PLoS One paper.

The prevailing view for decades was that dinosaurs were cold-blooded, as reptiles, fish and amphibians are today. Now support is leaning toward the warm-blooded dinosaur theory, which opens up a slew of intriguing questions: Did dinosaurs sweat? Were they able to live in very cold regions? Did they have to eat a lot to fuel their lifestyle? and more.

Herman Pontzer at Washington University in St. Louis and his team used a combination of computer modeling techniques and physiology know-how to predict the energy cost of dinosaur movement. They did this, reasoning that if walking and running would have burnt more energy than a cold-blooded creature could have put out, dinosaurs were probably warm-blooded.

Keep in mind that lizards and other cold-blooded animals do not use internally-generated energy to regulate their body temperature. As a result, they require far less energy than warm-blooded animals do. That's one reason why you often see them lounging motionless in the sun. And, conversely, why warm-blooded species like humans are usually hungry.

Prior research conducted by Pontzer's group showed that the energy cost of walking and running is strongly associated with leg length, so the distance from the hip joint to the ground can predict the observed cost of locomotion. After calculating these measurements and studying anatomical models of 14 dinosaurs, they determined that walking and running dinosaurs would indeed have used more energy than a cold-blooded animal would've been capable of producing. Conclusion: many dinosaurs were probably athletic, warm-blooded animals.

Of course, this is just one study, and the case hasn't been closed on the debate. But, for now, I'm going to enjoy the fact that dinosaurs may have been more like us than previously thought. If it's proven without a doubt that dinosaurs were indeed warm-blooded, expect some very cool new Discovery animation recreating the lives of hot and bothered dinosaurs.