Did an asteroid killed the dinosaurs?

Essay by misslyHigh School, 10th gradeA-, April 2013

download word file, 12 pages 0.0

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(This illustration of the K-T impact emphasizes that the dinosaurs were among the many victims of the catastrophe.)

Index:

Background: ………………………………………………………………………………………………….…………………….…3

Dinosaur information and extinction: ………………………………………………………………………………….…4

Asteroids……………………………………………………………………………………………………………….……5

The main idea of dinosaur extinction………………………………………………………………….………6

Main alternative idea of dinosaur extinction………………………………………………………….…..7

Arguments for………………………………………………………………………………………………………….…8

Arguments against……………………………………………………………………………………………………..9

Comparison……………………………………………………………………………………………………………....10

Conclusion………………………………………………………………………………………………………………...11

References......................................................................................................................12

Background

Scientists first learnt about dinosaurs in 1820s, when they discovered the fossilized bones of unknown creatures.

Reference: Children's illustrated encyclopedia. (Abridged edition)

Image above shows worldwide distribution of dinosaur footprint discoveries. About 1,500 locations have been known to yield dinosaur tracks.

How do we know dinosaurs existed?

We know that dinosaurs existed because of the fossils they left behind.

Their fossils come in many types, from preserved bones to tracks and more. Some fossils are better preserved than others and show impressions of skin and other soft tissues. Because of their remains that they have left, we know that dinosaurs existed!

How do we know how old they were?

Method #1 Dinosaurs are too old for carbon dating. Instead we use radio isotope dating of the rocks they are in. By measuring the ratios of various types of atoms we can determine how much of certain radioactive substances were in the rock when it was formed, how much is left, and how long that deterioration would take. This gives us an idea of how old the rock is (give or take a few hundred thousand or even millions of years).