After the Dwyka glaciation of the Carboniferous, which buried the whole of southern Africa under a thick ice sheet, more congenial living conditions developed during the Permian (ca. 300-250 million years ago). With the gradual temperature rise, temperate to subtropical conditions developed and new species appeared on the scene, whose fossil remains tell the story of their life. Some of them, such as the alligator-like reptile Mesosaurus tenuidens, are very distinct, and help to reconstruct the extent of palaeo-environments and climate zones from Southern Africa into South America, which at the time formed part of the Gondwana supercontinent. But not only animal life flourished, and one of the best sites to see the relics of ancient woods in situ is the Petrified Forest, some 45 km west of Khorixas.