One of the early carnivorous synapsids, Dimetrodon is well
known from the many remains that have been discovered in
the Red Beds of Texas, USA. All parts of its skeleton have
been found and they show a long, low predator with big,
powerful jaws and sprawling legs, which could probably run
rapidly. The most unusual feature of Dimetrodon was a tall
flap of thin skin on its back, held up by a series of spine-like
bony rods from the backbone. This has led to its common
names, such as 'sail-back' or 'fin-back'. The skin may have
helped to absorb heat from the sun,
allowing Dimetrodon to warm up
faster and move more quickly
than its contemporaries. A similar
reptile from the same time and
place, plant-eating Edaphosaurus,
also had the feature. During the
later Mesozoic Era, various
dinosaurs, such as the huge
predator Spinosaurus, had a
similar feature.