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Extinction Of Dinosaurs Essay

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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 …show more content…

Any one of these events, theorized by paleontologists, could have brought an end to the dinosaurs and all the other species that died with them. Since there are many theories about this I will not write about them all.
I have chosen the theory about death by Cosmic Collision (an asteroid).
In 1980 Luis Alvarez and John Sepkowski Jr., famous geologists, blamed the extinction of the dinosaurs on a large celestial body which hit the Earth 65 million years ago. According to them, an asteroid five miles across blasted through the Earth's crust, and threw up molten rock, ash, and dust. Adding to the support to this theory is the discovery of a layer of iridium in New Zealand,
Denmark, and Italy. This layer became known as the iridium anomaly. Remarkably, this layer of iridium was found in sedimen tary rock that is abundant on other celestial bodies. This was too remarkable to be a coincidence, so the research team decided that the layer of iridium must have been caused by space debris which resulted from the collision of Earth and another celestial body. At first,
Alvarez's theory was not widely accepted, but as more iridium was found from that period of time around the world, it became the leading theory. Other evidence includes the discovery of stishovite, a mineral created by high heat and pressure. These two

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