The earth was still in the process of change as the Early Cretaceous began. The land masses were drifting and the climates were changing. These changes affected the plant and animal worlds. Dinosaurs were becoming more plentiful and many more types were evolving. Some of the more fanciful dinosaurs with unusual crests and frills appeared. In contrast to earlier periods, dinosaurs at this time were different in different areas. Dinosaurs in Africa developed sails, while their relatives in the northern hemisphere did not have them.
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When the Early Cretaceous Period began 144 million years ago, the huge land mass known as Pangaea had already started to separate. Laurasia (present-day North America, Europe, and Asia) was almost completely separated from Gondwanaland (present-day South America, Africa, India, Antarctica, and Australia). Antarctica and Australia were separated from Africa and moved southeast across the Indian Ocean. India headed northeast. Africa was separated from South America, which became an island continent. Only Eurasia stayed attached to North America during the Early Cretaceous. Rifts in the Tethys Sea grew during this period.
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The Early Cretaceous world was very warm. There were wet and dry seasons rather than summer and winter. Most areas of the world were covered by tropical and semitropical jungles. The low-growing plants were ferns and fernlike vegetation. Plants of medium height were the cycads and their relatives. Treelike plants over 60 feet tall were mostly tropical conifers, ginkgos, and czekanowskian trees (an extinct group of trees with long, needlelike leaves). Fast-growing angiosperms-flowering plants-appeared for the first time.
Surprisingly modern-looking frogs, salamanders, turtles, and crocodiles lived in the rivers and lakes. Snakes had only begun to evolve, but there were many lizards, along with primitive furry mammals. All these animals provided food for small predatory dinosaurs. The long-tailed pterosaurs from the Jurassic were replaced by short-tailed ones, including Anhanguera, Tropeognathus, and Tupuxuara.