The History of life
The Earth was doubtless, already more than two billion years' old. This alone is a staggering length of time when we judge it by our usual standards of years, decades and centuries. But in the total history of all life a million years is but a moment. Between two and three billion years ago, in the darkness of the unknown past, the first life appeared.
It is impossible to comprehend the length of time that has passed since life first appeared on earth. But unimaginable immensity of the age of the planet earth and the time of life upon it has led to the multitude of living things we see today.
Life started in the sea. The first life forms were simple organism made of one cell. Over the millions of years living things gradually grew larger and complex.
Early animals had soft bodies and then grew hard shells. Plants spread over the land about 430 million years ago, immediately followed by the first amphibian.
Geologic Time
The first Reptiles evolved from amphibians. Unlike amphibians, reptiles could lay their eggs on land and spend more time on land. But some amphibians went back to sea and stay in water while some started to glide, and then fly. Reptiles who lived on land in turn gave rise to birds and mammals. In the Mesozoic era, after dinosaurs died out, mammals began to dominate the earth. One of the dominant members of mammals who roamed Africa, America and Asia is mammoths, the great grand -father of present Elephants.
Mammoths, specially northern Asian Mammoths grew thick hairy coats, because of which early humans hunted them for and for their meat as well, is one of the reasons for their extinction.
Evolution of the Elephant
Over the past 40 million years, more than 600 species of elephants have roamed the earth. Today only two species are alive—the African elephant and the Asian elephant.
About 65 million years ago from now, during the “ Eocene period” the last link of the present day elephant “ the Mortherium” was present. This creature had an organ like a trunk which was not long. The height upto the shoulders was about three feet. This animal was some what bigger than the tapir we see today. Moritherium is the great grandfather of the present day elephant and those like them.
When it came to the “Moecene period” the animal that looked like an elephant was known as “Trylophodon”. This animal which was about 10 feet in height is two feet longer than the “Moritherium”. Trilophodon had a long trunk ( about 7 feet) and two tusks. During the same period milk-fed animals (mammals) like the elephants were to be seen in Asian and African countries.
These animals were known as “Platybelodon”. These animals were about 12 feet in height. They had a short trunk which was bent down. Extinction of these animal species ( “Platybelodon” and “Trilophodon”) happened during the “Pliocene period”.
The Mammoths, another great grand-father of the elephant existed during the “Pliocene period”. These animals had pair of big tusks bent forward. They were bigger than the tusks of the present day elephant. These mammoths who had no hair on them ( except for Northern Wooly Mammoth ) lived in Asia, Europe and North America. Mammoth who lived in the Siberian areas of Europe had thick hair (Wooly Mammoth ).
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