WEIT Chap2
What is a fossil?
A fossil looks like a stone, but it is not really a stone. It is a memory of an animal that lived a long time ago. The addition of a time factor and chemical reactions formed it. We will explain precisely how a fossil is formed later.
Between myths and truth
During the Greek period, people didn't know what these tracks were. This probably gave rise to mythology.
Much later, in the nineteenth century, people thought fossils were made by supernatural forces, results of religious cataclysm or unknown species of far living animals.
How are fossils formed?
The formation of a fossil is called fossilization. It begins as the rest of a dead organism (animal or plant) falls in water or in a wet environment. The organism's body's decompose. As this happens, the rest of the animal is covered by sediments during ages. The sediments and the bones are transformed in a kind of stone which wears the track of the organism. Erosion and extreme climatic phenomena reveals the fossil. That is why we can discover animals that were born thousands or millions of years ago!
Are fossils easily found?
Fossils can be found everywhere.
How can we determine the age of rocks ?
Once fossils are classified, we can see what appeared kind of organism appeared first.
Why are fossils important for Evolution study?
Fossils are the evidence of evolution. Without them, we would have only a "theoric" sketch of how species evolved throughout the centuries.
What is the "fossil record" ?
Historically speaking : what people thought of them (supernatural forces)
Fossils and birds...
Fossils in the sea...
What information can we find in fossils ?
Which problems can we have with fossils ?
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