Permian period (290 to 240 million years ago) The world map indicates that Pangea as a supercontinent commenced from arctic and reaches antarctic. In this supercontinent, because of long distance to the sea, climate change occurs and deserts develop. A group of vertebrate beasts was produced independently from seasonal rainfalls. They produced new types of egg. These eggs could be laid on land. They had very hard shells and nutritional yolk and white. The style of neck and feet assisted these animals to walk better. These animals could walk in a long distance on Pangea. They were not amphibians, but were reptiles. Reptiles, which were similar to huge mammals, scattered throughout the supercontinent. A decrement of water level could decrease the sea depth. Therefore, complete extinction of trilobites, tabulata (a group of corals) and rugosa occurred during this period. Big groups of bryozoans, brachiopods, sponges and crinoids were disappeared in this period. The biggest extinction of animals' life history occurred between Paleozoic and Mesozoic, especially in late Permian. Although the life of many living things were really impressed in different environments, but the important effect of extinction was on marine invertebrates. A small number of animals could rescue from this extinction, but never reached their former situation, numerically. A relatively small extinction regarding diapsida and synapsida opened the way for other living things. Therefore, a new era calling “Dinosaurs Age” commenced. Meanwhile, big forests of fern-like plants converted to gymnosperms. Advanced pines, the most familiar type of plants, which are very similar to recent gymnosperms, occurred in this period of time. In sum, Permian was the period of extinction of certain living things that they were in their climax and development of other types. Life on the Earth has never been again like Permian. The general geography of Permian includes an integrated ocean and land. In early Permian, continental drift process produced an integrated piece of land under the name of supercontinent, Pangea. Most of the present day continents could be observed in Pangea. Only Asia remains separated continuing from Arctic to Antarctic at that time. The biggest ocean of that period was called Panthalassa. A smaller sea was also available at the eastern part of Pangea under the name of Tethys. Available models indicate that the internal parts of Pangea were dry lands holding big seasonal changes. As these regions were far from sea, its regulating effect on temperature was not available. Only certain parts of the region tolerated annual rainfalls. Slight information is available on Panthalassa. A couple of signs could be found on the Earth's climate change. The glaciers' areas decreased and internal parts of Pangea became drier.