Dimetrodon
Dimetrodon was a sail-backed meat-eating animal that lived during the Premian Period, roughly 280 million year ago, long before the dinosaurus evoloved. It was so-called mammal-like reptile, an ancestor of the mammals. Dimetrodon was about 11.5 feet (3.5m) long and weighed roughly 550 pounds (250kg). It had a large sail-like flap of skin along its back, dense with blood vessels. The sail was supported by long, bony spines, each of which grew out of a separate spinal vertebra (a bone in the back). The sail may have been a thermoregulatory structure used to absorb and release heat. The sail may have also been used for mating and dominance rituals and/or for manimg it look much alrger than is was to predators. Dimetrodon had sharp teeth and clawed feet.
