Dimetrodon grandis

Before dinosaurs ruled the Earth, a different type of big lizard dominated what is now North America. Dimetrodon was the largest land predator 260 million years ago. This reptile had two types of sharp teeth that were advanced for its time and a tall ''sail'' on its back that helped control the creature's body temperature.

> **Shear Terror:** Dimetrodon had two kinds of teeth in its jaws-sharp canines for stabbing and jagged teeth for cutting. When its mouth snapped shut around prey, the creature slid its lower jaw backward to slice the meat.
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> **Side Step:** Though it looked like one, Dimetrodon was not a dinosaur. The biggest difference was in its legs-they grew from its sides, like a crocodile; a dinosaur's legs came straight down from underneath its body.
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## Creature Features

### Size:

Length up to 11.5 ft.' Sail height up to 5 ft.; weight up to 550 lbs.

### Where?

Fossils have been found in Texas, New Mexico and Oklahoma

### When?

280 to 260 milion years ago, during the Permian Period

## Just Warming Up

The huge sail on Dimetrodon's back covered long spines that rose frm the lizard's backbone. The wide surface area of the sail was packed with blood vessels that collected heat from the sun, warming the creature by as much as 11'F within 90 minutes. Dimetrodon turned this heat into energy so it could move around quickly while hunting. At night, the sail released heat quickly so the reptile could rest.

The majority of Dimetrodon fossils have been found in Southwestern U.S.

> **Mammalsaur:** Dimetrodon's specialized teeth were more advanced than those of many dinosaurs that appeared 30 million years later. This has led scientists to believe this reptile was more closely related to mammals than to dinosaurs.
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> **Cool Off:** If this reptile's body became to hot, it would have stopped functioning and died. Dimetrodon crawled into the shade or turned its wide sail toward a breeze to cool itself.
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### Did You Know?

Scientists once thought that Dimetrodon's sail was used to catch wind and help the creature swim fast.

## Early to Rise...

1. As the sun rises one morning during the Permian Period, a Dimetrodon prps itself up and turns its sail to face it.The blood vessels in the sail collect heat quickly and distribute it to the creature's vital organs.
2. Full of energy after 90 minutes, the Dimetrodon runs in search of prey. Finding another reptile resting in the sand, the predator pounces. Without the aid of a sail, the victim doesn't have enough energy to flee so it becomes Dimetrodon's breakfast.

Before dinosaurs ever existed, this lizard ruled. Dimetrodon had long, stabbing teeth that sunk into prey. It used the frill on its back to energize itself when chasing prey.

* **Say What?** The frill on Dimetrodon's back may have changed color with the creature's mood.
* **Life:** 90
* **Attack:** 4
* **Defense:** 3

### Say What?

This reptile's sail might have been brightly colored to attract mates.

### Defense:

10

With an energy-storing sail and two types of shearing teeth, Dimetrodon was one of the most feared hunters of its day. This reptile roamed the Earth 30 million years before the dinosaurs.

Dimetrodon---the mammal-like reptile that is often mistaken for a dinosaur.