1. Great big and fearsome Dimetrodon, a species of dinosaur, was the most powerful creature.

2. 16 Great big and fearsome Dimetrodon, a species of dinosaur, was the most powerful creature.

3. Unlike tyrannosaurs, ancient predators like phytosaurs and Dimetrodon had no adaptations to prevent the crack-like serrations of their teeth from spreading when subjected to the forces of feeding.