Dimetrodon

Dimetrodon is often shown with dinosaurs, but it was not a dinosaur at all! It lived about 280 million years ago, which is 50 million years before the first dinosaurs. Dimetrodon is actually more closely related to mammals, including humans!

The Sail

The most famous thing about Dimetrodon is the large sail on its back. This sail was made of skin stretched over long spines growing from its backbone. The sail may have helped Dimetrodon warm up faster in the morning sun. This would have given it an advantage over slower, cold-blooded prey.

An Ancient Predator

Dimetrodon was about 11 feet long and weighed about 550 pounds. It was the top predator of its time. It had two types of teeth: sharp ones in front and smaller ones in back. This is why its name means "two measures of teeth." It ate other reptiles and amphibians.

Fun Facts

• Dimetrodon is more closely related to you than to any dinosaur!
• It lived about 50 million years before the first dinosaurs appeared.
• Its sail could be over 3 feet tall.

Did You Know?

Dimetrodon belongs to a group called synapsids, which eventually evolved into mammals. So in a way, Dimetrodon is a very, very distant relative of humans!