Cretaceous
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- Cretaceous: Age of Dinosaurs
- Period starts 144 to 65 million years ago. The cretaceous period is in the Mesozoic Eon and Phanerozoic Era. The name Cretaceous the metamorphosed deposits of the tiny limestone skeletons of diatoms is known as chalk. The Latin for chalk is creta, so the period was named Cretaceous.
- Before the Cretaceous period their was the Triassic and Jurassic period, and the Cenozoic Era comes after. During this time the breakup of the world-continent, also known as, Pangaea. It began to disperse as the Jurassic period continued.
- During the Cretaceous period , plate collision began causing mountains to form along the western margin of North America . As mountains began to form, the Gulf of Mexico subsided and seawater began to spread northward into western interior.
- During this time, we find the first fossils of many insect groups , modern mammal and bird groups, and the first flowering plants. This is the first appearance of Pachycepalosaurid dinosaur. A time traveler would likely be eaten during this period due to the high upcoming of dinosaurs. Plant life included ferns, conifers, and ginkgoes. These were the flowering plants (angiosperms) appeared early cretaceous period.
- Ammonites are the most widely employed fossils because of their frequent occurrence in each period. Much of this rich life became extinct over time such as, all dinosaurs, pterosaurs, pliosaurs, and ammonites. Before this, the climate was much warmer during this period because the atmosphere contained 3 or 6 times the amount of carbon dioxide than the current era.
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