The folk tales and legends of countries all over the world are full of wondrous creatures: terrible flying dragons, sea serpents, giant birds. These monsters are not found in any of our forests or deep seas.
Scientists know that creatures similar to the ones in these folk tales lived on earth very long ago, before man came into existence.
Imagine what would happen if these ancient giants were to come onto the streets of a modern city! Looking like sinister tanks, mighty cranes and enormous gliders, these fabled monsters would stop all traffic, tear electric wires, and knock down poles and boards and temple on houses and parks. But not worry. These ancient animals died millions of years ago!
But how do we know about them? -From the chronicle in rock. The chronicle in rock is the earth itself. And the page of the chronicle is the layers of sand and clay. The deeper the layers older are.
In the ancient parts of a city, beneath the concrete streets lie the streets of the olden days. In these layers one may find ancient coins, rusty-swords or utensils or broken pottery. Far below this, begin the page of the chronicle in rock. Here the sand has turned into hard sand- stone and mud and clay into plenty stone. There are no traces of human beings here. And yet these pages are as interesting as the pages of fairy tales.
The chronicle in rock is incredibly thick. Many kilometers separate the upper pages from the lower ones. And the pages are heavy. Human beings cannot turn them. Nature helps in this regard. Movement inside the earth rumples and turns upside down these rock layers in the mountains and hills. The wind and water dig deep gorges and through them we can see the oldest pages.
It was in such places that people once saw giant bones, after which they invented tales of dragons and giants and other fantastic creatures.
An intricately –patterned fern sees to be drawn on a smooth hard stones. Try to rub out the drawing. It won’t come off. This is a petrified fern from an ancient forest. A beetle has spread out its wings nearby. It is also petrified. One it had crawled on the fern. A tiny wasp crawling on the bark of a tree got caught in a drop of resin oozing out. The resin was petrified and we can see preserved wasp, millions of years old. This is how a fossil is formed.
On a boulder are foot marks in the stone. They look like the prints of a crow. Only they are larger than an elephant’s. A starfish is flattened against white limestone; a school of little fish seems to be swimming through some sea cities. This is the petrified sea bottom. The razor- sharp teeth on the skull of a dragon-like animal shine out at us from the stone. And whose gigantic bones are these?
The chronicle in rock is read by scientists called paleontologists. They go to far off place in the mountains and deserts, where the ancient pages have come to earth’s surface. It is a difficult task to read these pages. They are often cracked or faded, or the bones of animals are mixed up, or the imprints of the shells, plants and insects been swept away.
Paleontologists can tell a lot about an animal from just one bone. They put together the bones they find and learn about the animal’s shape, where it lived and what it could do.
But everyone can’t read these rock pages.
The Paleontologists have told us what the earth looked like before human beings arrived, what animals and plants lived in the seas and on the and. They have read the chronicle in rock to as far back as 3,000 million years ago when life first had appeared in the warm waters of the ocean.