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Extinction Of Dinosaurs

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Extinction of Dinosaurs

Two-hundred and thirty million years ago the first dinosaur-like

creature roamed the earth. Within five million years it could be considered a

dinosaur. They were soon at the top of the food chain. They populated every

continent. Then 65 million years ago they vanished. The most powerful

creatures ever to live on earth had become extinct.

Dinosaurs were not the only victims of this "mass extinction." There

were many other species that were killed off. During what is known as the K-T

extinction (K stands for Cretaceous, T stands for Tertiary), many species and

families became extinct. These include all marine reptiles such as plesiosaurs,

mosasaurs, ichthyosaurs, and ammonites, swimming and flying reptiles, sea

crocodiles, and foraminifera. In addition to that there were many bony fish,

sponges, snails, clams, and sea urchins became extinct.

Paleontologists have proposed scenarios that could have caused these

extinctions. One such scenario involves the growing number of small mammals

which ate dinosaur eggs, and therefore caused the dinosaurs' birth rate to drop.

The birth rate became smaller than the death rate and the dinosaurs died out.

This, however, is not a plausible scenario. This would only account for the

dinosaurs, but not all the other creatures of that time. Paleontologists needed

to come up with a more plausible and de...
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