Was Tyrannosaurus rex Warm Blooded?

Publication Info:

Transcript:

RANDON J. FLORES, et al. The body temperature of Tyrannosaurus rex. Science Advances (2026). DOI: 10.1126/sciadv.aeb7653

Tyrannosaurus rex may be the world's most famous dinosaur, but there's only been limited evidence in the past for how it kept itself warm. Was it warm blooded? Was it cold blooded? Was it somewhere in between? 🌡️🔥 thanks to new, less destructive techniques, researchers now know that T. rex was a warm blooded, active predator, who didn't depend on the environment to stay warm.

Episode 345

Notes:

There's brand new T. rex news, and it's all thanks to teeth, just like this. I've been asked over and over if T-Rex is warm-blooded or cold-blooded. Usually, the answer is probably somewhere in between, more toward warm-blooded. And part of that is because the whole warm-blooded, cold-blooded dichotomy that a lot of us think of doesn't really work in nature. Like most things in nature, it exists on a spectrum. They're ectotherms, what we normally think of as cold-blooded. Ecto meaning outside, things like most lizards and snakes. And then there are endotherms, like mammals and birds. Endo meaning on the inside, we make our own heat. Then everything in between is generally called a mesotherm, and the the lines between endo, meso, and ecto get a little messy, especially because there are reptiles, lizards like the Tegu that is sometimes more of an ectotherm, sometimes more of an endotherm. Then, like I said, birds are warm-blooded. Birds are also reptiles. So, anyway, my point is the lines are messy, they get blurry, it gets weird, just like most things in nature. But at least now for one dinosaur, the most famous dinosaur, we may know its body temperature. An extinct animal's body temperature can be determined by the carbon and oxygen isotopes in their tooth enamel. But, in the past, it's been an incredibly destructive process. And most museums don't want to give up their best specimens to literally be destroyed. That said, researchers at UCLA have just found a way to do this exact same process in a much less destructive way, using far less material than in the past. And after analyzing T. rex samples, they have a body temperature. If you stuck a thermometer in a T. rex's mouth, it would read just about 97° Fahrenheit, barely cooler than us. Meaning that T. rex wasn't wasting its time sunning itself in perfect conditions so it could hunt. It was ready to go. It was an active pursuit predator, generating its own body heat, no matter where it had to hunt. Obviously, this isn't the first data indicating that T-Rex could do this, but it is a solid confirmation for data that's been found in the past. As usual, if you want more information, here's the source.