Dimetrodon (/daɪˈmɛ.tɹəʊˌdɒn/) ("two measures of teeth"), was a predatory synapsid ('mammal-like reptile') genus that flourished during the Permian Period, living between 280 and 265 million years ago. It was more closely related to mammals than to true reptiles (Sauropsida), like dinosaurs, lizards and birds. Dimetrodon was not a dinosaur, despite being popularly grouped with them. Rather, it is classified as a pelycosaur. It is surprisingly well-known to the general public and makes an appearance in the James Mason film Journey to the Centre of the Earth, as well as in Yor, the Hunter from the Future. Fossils of Dimetrodon have been found in North America and Europe, as well as a significant discovery of Dimetrodon footprints in southern New Mexico by Jerry MacDonald. The climate of Europe and North America in the Early Permian, was probably arid to continental, so Dimetrodon was probably adaptable.Dimetrodon was an apex predator, among the largest of its day. It grew to up to 3 1/2 metres (11 feet) in length. The name Dimetrodon means 'two-measures of teeth', so named because it had a large skull with two different types of teeth (shearing teeth and sharp canine teeth), unlike reptiles. Dentition showing this differentiation of teeth is called heterodonty. It walked on four side-sprawling legs and had a large tail. Dimetrodon may have moved in a manner similar to present-day lizards.