Dimetrodon

The Dimetrodon is a three-part fossil that can be donated to the museum in, , , and.

In Wild World
"It lived early on, when dinosaurs first began roaming the earth, wot? And actually, to be quite accurate, it's not even a real dinosaur at all! As we know, dinosaurs were cold-blooded and could not change body temperature. But the dimetrodon could! It used its distinctive back to control heat! For this reason, it is considered what we call a "mammalian reptile," wot? Ah. Hoo. Yes, sorry. I got rather blabby, there. I got heated up, hoo!"

In City Folk
''"...And with that, the dimetrodon is complete! Hoo, what a spectacle! The dimetrodon was from a period early in the history of the dinosaurs, eh wot? In point of fact, it's not even a real dinosaur! That's because it could regulate body temperature, unlike other dinosaurs. The dimetrodon did so by using its distinctively shaped back... Indeed, and that is why it's considered what some call a 'mammalian reptile'!"

In New Leaf
"Despite its reptilian appearance, the dimetrodon was not actually a dinosaur, as you'd assume. It was, in fact, a mammal-like reptile that went extinct before the first dinosaurs appeared. It had knife-like teeth for slicing as well as smaller ones for crushing. The large fan on its back was used to regulate body temperature-- an important feature of the time."

In New Horizons
"Ah yes. Dimetrodon. Not actually a dinosaur, despite what...some people may tell you. This REPTILE- not dinosaur -is most famous for the large sail-like organ on its back. Said organ was likely useful in regulating its - non-dinosaur -body temperature. Reptiles are known to be cold-blooded, but there is some debate as to whether dinosaurs were too. Dimetrodon assuredly was. "

In Real Life
The dimetrodon was a lizard shaped dinosaur. It was a carnivore and had a fan to regulate body temperature.