Jim Zulaufs age 10, of Pittsburgh, Penna,.. for his question?

Why did prehistoric animals become extinct?

The most dramatic prehistoric animals were the dinosaurs who said goodbye to the world some 60 million years ago, These animals were reptiles, some big and some small: They thrived in warm, damp weather and most of them fed on coarse water plants. Throughout their long reign, the climate of the world was mild and wet and much of what is now dry land was covered with swampy seas of fresh water.

All this time the world was just right for reptiles, which is why the dinosaurs were able to thrive, to grow so big and so numerous. The reptiles of this age were so successful that they branched forth into countless shapes and sizes: One toothy variety took to the air on huge, leathery wings, Just when the world was crowded with countless different varieties of healthy dinosaurs, things changed,

The climate became dry and perhaps much colder, The swampy stretches disappeared and with them the masses of water plants, The plant eating dinosaurs could no longer exist, There were no shallow waters to support their clumsy bodies and there was no food, The dinosaurs who fed on the plant eating dinosaurs were also in trouble. What's more, small mammals had come to live in the world and these smarter creatures were raiding the eggs left in the ground by the big reptiles,

Things went from bad, to worse and soon the last dinosaur said goodbye and disappeared from the earth forever. But this is not such a sad story as it seems. The mighty dinosaurs had ruled the world for over a hundred million years   which is quite a success story, Whatts more, some of their children went on changing and developing, Would you . guess that our dainty feathered birds are descended from the same ancestors as the dinosaurs?

Some 500 million years ago, long before the dinosaurs, the most advanced animals in the world were the trilobites, crusty little creatures who lived in great numbers on the floors of the ancient seas. Through the ages, some of the trilobites improved themselves, Some learned to curl into round balls and make themselves safer from their enemies. These fellows had a better chance of surviving. The original trilobites became extinct millions of years ago, but some of their descendants went on improving and they did survive. Our crabs, lobsters, insects and spiders can all trace their family trees back to trilobite ancestors.

Less than a million years ago saber toothed tigers, wooly mammoths and giant sloths roamed all over North America. These animals became extinct sometime during the last Ice Ages. There are different reasons why each of these prehistoric animals failed to survive. Some could not cope with the weather, some could not defend themselves against new enemies. But all of them failed because they could not adjust to some new circumstance that came into their lives. The failures were those who could not learn a new way of living.