Cretaceous

North America circa 70.4 mya

The Cretaceous was the last and longest period of the Mesozoic. Land and sea temperatures rose during the first half of the period; there were tropical swamps in Africa, South America, India, Australia and Europe, coal swamps along the northern shore of Alaska, and hot deserts in Mongolia. Dinosaurs lived above the Arctic Circle and in the Antarctic, enduring the cold of the month-long nights.

Climate

In general, the climate of the Cretaceous Period was much warmer than at present, perhaps the warmest on a worldwide basis than at any other time during the Phanerozoic Eon. The climate was also more equable in that the temperature difference between the poles and the Equator was about one-half that of the present. Floral evidence suggests that tropical to subtropical conditions existed as far as 45° N, and temperate conditions extended to the poles.