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What Are Fossils?

The study of fossils is so important in helping man learn about his own past and that of animals who lived millions of years ago that it has developed into a separate science called paleontology.

Fossils are not as some people think, the remains of bodies buried ages ago. Actually, there are three different kinds of fossils. The first is part of the actual body of the organism, which has been preserved from decay, and which appears just as it was originally.

But fossils may also be just the cast or mold of the shape of the body, which remains after the body of the plant or animal has been removed. And fossils may merely be the footprints or trails that animals have left as they moved over the soft muds or clays.

When a fossil is found that consists of part of the organism itself, it is usually only the hard parts, such as shells or skeletons, that are preserved. The softer parts are destroyed by decay.

Yet, in some cases, even such soft-bodied animals as jellyfish, which are 99 percent water, have left perfect fossils of themselves in rocks! And certain fossils found encased in ice not only have the skeleton preserved but also the flesh and skin on the bones.

Fossils have nothing to do with size. For instance, the fossils of tiny ants which lived millions of years ago can be found perfectly preserved in amber. The chances for animals being preserved as fossils depend mostly on where they lived.

The most numerous of all fossils are water animals because when they die their bodies are quickly covered over by mud and so kept from decaying. Land animals and plants are exposed to the destroying action of the air and weather.

It is chiefly through the study of fossils that we know about animal life as it existed millions and hundreds of millions of years ago. For example, fossils taken from certain rocks tell us that millions of years ago there was an Age of Reptiles, with monsters so huge that they were 80 feet long and weighed 40 tons.

These were the dinosaurs. And our entire knowledge about the earliest bird, called the archaeopteryx, is based on just two fossils of it that have been found!

Read: How Are Caves Formed?