The earth is alive with life. Mountains, prairies, deserts, beaches, lakes, rivers, and seas-living things inhabit every part of land, sea, and air. There are an enormous number of different species of living things. There are over 350,000 plant species and 1,120,000 animal species known.
How did so many different species come to be? Is it true that life has always been the same as it is now? For thousands of years, men have pondered these questions. To find answers, we must look to fossils as well as knowledge of living organisms and their structures. Only an understanding of living animals can breathe life into millions of year old bone and shell fragments.
The elephant is the largest land animal alive today. However, the study of fossils reveals not only that elephants are a recent group in the long history of living things, but that early elephants resembled hogs. Geologists piece together the history of elephant evolution by tracing elephant fossils from older to younger rocks. Although fossil bones and teeth reveal the structure of early elephants, complete reconstructions of extinct elephants can be made with reasonable accuracy by studying these fossils in light of the anatomy of living elephants. Some unusual occurrences of mastodon fossils with crude flint weapons demonstrate that our ancestors hunted these elephants.
EVOLUTION OF ELEPHANTS
MASTODON Pleistocene 1 Million Years ago.
TRILOPHODON U. Miocene-L. Pliocene 10-20 Million Years ago.
DINOTHERIUM Miocene-Pleistocene 1-25 Million Years ago.
MOERITHERIUM U.Eocene-L. Oligocene 20-40 Million Years ago.
Elephants are descendants of an ancient, more widespread, and diverse group that evolved from pig-sized ancestors in the Upper Eocene. (See pp. 30-31 for the geologic clock.) Only a few of the many extinct elephants and their relatives are depicted.
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