Edaphosaurus was a prehistoric reptile that lived during the late Carboniferous to early Permian periods, around 300 million years ago. It belonged to a group called synapsids, which are often referred to as "mammal-like reptiles." Edaphosaurus was notable for its large, sail-like structure on its back, formed by elongated neural spines, which may have been used for thermoregulation or display. This herbivorous creature could grow up to 10 feet long and had a broad, flat skull with specialized teeth for grinding plant material. Edaphosaurus is often compared to its relative, Dimetrodon, which had a similar sail but was a carnivore. Both are important for understanding the evolution of early terrestrial vertebrates.