The pelycosaurs (from Greek πέλυξ - pelyx and σαῦρος sauros "lizard") were primitive Late Paleozoic synapsid Reptiles. Some species were quite large and could grow up to 3 meters or more, although most species were much smaller. Evolutionary history The pelycosaurs appeared during the Late Carboniferous and reached their acme in the early part of the Permian Period, remaining the dominant land animals for some 40 million years. A few conti… (More on Pelycosaur)