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The Cretaceous Period Essay

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The Cretaceous Period

The Cretaceous period was the last and longest part of the Mesozoic Era. This period of time lasted around 79 million years! It lasted from the end of the Jurassic Period’s extinction (145 million years ago) to the beginning of the Paleogene Period (65.5 million years ago.) In this time, the earth’s continents were not in the same shape as they are today. Pangea, the supercontinent, was still drifting apart from itself. The ocean was still separating Northern Laurasia and Southern Gondwana, however the North and South Atlantic were still closed. The Central Atlantic had already started to open up during the Jurassic Period. By the middle of the Cretaceous Period, the ocean levels had risen and the placement of the continents were similar to what they are today. South America and Africa had gotten their shapes by this time, but India and Asia did not join yet, nor did Australia separate from Antarctica.

The climate
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The end of this period happens to be one of the most famous extinctions. This was the extinction when all of the dinosaurs died out, except for the birds. About 65.5 million years ago, nearly all large vertebrates and many tropical invertebrates became extinct. So, what caused this mass extinction? Scientists still do not have a definite answer, but they do have two hypotheses’. These hypothesis are that an extraterrestrial impact, such as an asteroid or comet, or a massive bout of volcanism put an end to it. Either of these things would’ve choked the skies with debris, which would’ve blocked the suns energy. The block in the suns area would’ve caused a lot of harm to photosynthesis, therefore many animals would not have a food source to supply them with the necessary nutrients. By the end of the Cretaceous period, all large and small ruling reptiles, except the crocodile became extinct. Whatever the explanation to this extinction was, it resulted in the Cretaceous Period
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