Prehistoric Dimetrodon figure This toy is large, solid and heavy It lived during the early Permian period, around 295–272 million years ago. The most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. Although commonly mistaken for a dinosaur, it lived 40 million years before the dinosaurs evolved. See pictures Pickup in Langford Cross posted