Wes Vaughn, age 8, of Marietta, Ga., for his question:
WHY DID THE DINOSAUR BECOME EXTINCT?
Dinosaurs were the world’s most dominant animals during the Mesozoic era, which ran from about 225 million years ago until about 65 million years ago. Scientists have be en able to tell us quite a bit about these ancient animals. These special scientists, called paleontologists, have been able to reconstruct the habits of these creatures by studying their fossil remains.
All kinds of dinosaurs lived during the Mesozoic era.
They ranged in size from two and a half feet long to a meat¬eater who stood 20 feet high and a plant eater who measured 90 feet in length.
Dinosaurs were actually reptiles. The plant eaters lived on vegetation, while the meat eaters ate other dinosaurs. There were two groups: one had hips similar to those of the modern lizard, while the other had birdlike hips.
A number of different theories have been given by the scientists as to why the dinosaur has become extinct. The basic cause is probably because mountain ranges developed while the dinosaurs lived. When great mountain ranges were formed, seaways were drained from the continents and wide swamplands that had been the homes of the dinosaurs gradually dried up. Great climate changes also came about, and food supplies disappeared.
Dinosaurs had become adapted to certain conditions, and when these changed rapidly, the creatures could not quite adjust to their new environments. Old plants died out and new ones developed, but the plant eaters could not eat them. When they died off, the meat eaters were without food and they too disappeared.
Scientists also believe that, as the world changed, mammals developed with brains that were better than those of the dinosaurs. The ancient reptiles probably disappeared slowly over a 10 or 20 million year period of time.
Another reason the dinosaur became extinct is that he probably developed a number of diseases that he could not fight.
Dinosaurs ruled the earth for 145 million years. The name comes from the Greek words dinos, meaning terrible, and sauros, meaning lizard. The reptiles certainly did look terrible, but they were definitely not lizards.
Tiny brains seemed to be the one thing all dinosaurs had in common. Their other features varied greatly: some were small, while others were large; some walked on two feet, while others were four footers; some had smooth skin, and others had scaly or bony plate studded skin. They laid their eggs on land, like other reptiles.
Scientists figure large dinosaurs probably lived to be more than 100 years old.