Phanerozoic the Mesozoic features the rise of reptiles on their 150 million year conquest of the Earth on the land, in the seas, and in the air. There are three periods in the Mesozoic: Triassic, Jurassic, and Cretaceous. The Triassic ranges from 250 million to 200 million years ago. The Triassic is a transitional time in Earth's history between the Permian Extinction and the lush Jurassic Period. It has three major epochs: Early Triassic, Middle Triassic and Late Triassic. The Early Triassic lasted between 250 million to 247 million years ago, and was dominated by deserts as Pangaea had not yet
South Polar region of the Cretaceous temperatures caused by the high amounts of carbon dioxide and possibly methane greenhouse gases in the atmosphere. This caused a lack of permanent ice coverage in the polar regions, though the carbon dioxide level dropped between 115 and 66 million years ago (mya), possibly allowing some permanent ice cover. It is possible that, throughout the Cretaceous, several small ice sheets developed. Increased tectonic activity, causing more geothermal heat, may have prevented glaciation and increased global temperatures. Temperatures may have been up to 15 °C (27 °F) warmer than they are in the modern age. The landscape of the Middle Jurassic