Polar forests of the Cretaceous Polar forests of the Cretaceous Cretaceous polar forests were temperate forests that grew at polar latitudes during the final period of the Mesozoic Era, known as the Cretaceous Period 145–66 Ma. During this period, global average temperature was about higher and carbon dioxide (CO) levels were approximately 1000 parts per million (ppm), 2.5 times the current concentration in Earth's atmosphere. The abundance of atmospheric carbon dioxide had a very significant impact on global climate and Earth's natural systems as its concentration is considered one of the main factors in the development of a pronounced greenhouse Earth during the Cretaceous with
The Age of Reptiles the mural's beginning to the end of the Cretaceous period, 65 million years ago. Each period's length on the mural is proportional to the period's length in geologic time. Each period of time is divided by large trees in the foreground. Animal species are in bold. Devonian Carboniferous Permian Triassic Jurassic Cretaceous "The Age of Reptiles" won Zallinger several awards. Zallinger was awarded with a Pulitzer Fellowship in Art in 1949, and the painting was featured as a postage stamp in 1970. Despite its somewhat outdated view of dinosaurs, "The Age of Reptiles" is still notable for its historical and