Peggie Hannigan,, age 10, of Westfield, Mass., for her question:

Were the dinosaurs amphibians?

A little lizard looks very much like a salamander. But the lizard is a reptile, and the salamander is an amphibian. The dinosaurs came in all. Shapes and sizes. Some of them looked like rhinoceroses, some like overgrown ostriches and others like giant lizards or salamanders. But all of the amazing dinosaurs were lizards.

About 300 million years ago, the land was invaded by stubby legged amphibians. They were the first backboned animals to leave the ancient seas to live in the swampy forests and along the marshy shores. They looked like giant salamanders., and some of them grew seven feet long. For 100 million years, the salamanders had the land to themselves.

Meantime, other backboned animals had left the seas for life on the dry land. They were the ancestors of the lizards. The soft skinned amphibians had to stay in moist places. Like the froggy amphibians of today, they had to spend their egg and tadpole stages in the water. The lizards left their eggs to hatch in the dry, sandy soil. And they did not have to keep their scaly skins moist.

The lizards were able to travel far from the seas and the marshes, and soon they became the most important animals in the world. Their children thrived and grew bigger. They branched out in different forms. About 200 million years ago, the family of lizards called the dinosaurs ruled the earth.

Lizards, of course, are reptiles and very different from the amphibians. The word amphibian is coined from older words meaning land and water. An amphibian deve1ops from an egg, then through a fishy tadpole stage. In the third stage of his life he becomes an adult frog or toad, salamander or mud puppy

Some of the bulky dinosaurs lived in marshes with only their snaky necks above the water. A few dinosaurs lived in the sea. Some of them grew leathery wings and learned to fly. But all of them hatched from eggs into miniature copies of their parents. None of them went through a tadpole stage as the amphibians do. This is why the dinosaurs are rated as lizards and not as amphibians.

The age of reptiles lasted for almost 180 million years. All this time., the dinosaurs were the most important land animals in the world. As the dinosaurs became bigger, the amphibians became smaller. There are still descendants of the ancient amphibians in the world, but the mighty dinosaurs did not survive. We do not know why, but about 60 million years ago, the last of the dinosaurs perished frown the earth.