Interval of approximately 448 million years (299 - 251 million years ago). During the Permian the continent joined to form a single supercontinent, Pangea. Hot and dry conditions prevailed almost everywhere and deserts were widespread. Life evolved as a continuation of established lined. Marine and fresh water fishes and amphibian thrived. Reptiles evolved into three distinct groups – the cotylosaurs, the pelycosaurs and the therapsids. Land plants evolved from ferns and seed ferns to conifers and adapted to drier and well drained land condition. Toward the end of the Permian Period, the largest mass extinction in Earth’s history took place.