Bill Wakefield, age 11, of Indianapolis, Ind., for his question:

How do we know that there were dinosaurs?

Early in the last century, most thinking people were sure that this world of ours was about 6,000 years old. Sometimes they noticed strange scratchings on the rocks and sometimes they found strange bones buried deep in the earth. Most people explained these things as the work off` Noahts flood. Mountains of water would tear at the rocks and many creatures would naturally die and be buried in the muddy silt.

Then, around 1836, a young Swiss professor named Louis Agassis came up with a better explanation for some of these things. He had seen these aorta of glaciers in his native Alps and was certain that similar glaciers had been at work in other parts of the world. With more and more detective work the scientists were able to prove that there were lee Ages, millions of years in the past. The old earth had had far more birthdays than most people thought.

Soon after this discovery, the whole world became interested in buried bones. We call them fossils, meaning something dug up, and some of them are far, far older than Noah's flood   even older than the remote Ice Ages. The study of fossils is called paleontology. Though it is less than two hundred years old, this science has already shown us how to turn back tine pages of earth's history for millions of years.

A paleontologist must know a great deal about the rocks in which he digs. He must know how they were made, whether by muddy silt in some shallow sea or by some fiery volcano. He must know the age of his rocks and when they were formed. This is one way to date the fossils he finds there. After countless hours of painstaking detective work, we now know that living things have existed on earth in a long parade for at least 500 million years. .¬

Long before the Ice Ages wire dated, strange footprints had been assn in the rocks of the Connecticut Valley. They were two footed tracks and seemed to be made by giant birds. Later, giant bones were found in the western deserts. Whole skeletons were put together and when we see these monsters in a museum we dust have to believe our own eyes. The evidence of the rocks shows that many of them lived 100 million years ago. Some of them walked on two feet, feet like those which made the strange tracks in the Connecticut Valley.

Bit by bit we learned about the countless varieties of dinosaur. We found imprints of their scaly skins and fossil dinosaur eggs. In the soil inside one giant rib cage we found a number of smooth pebbles. This suggests that at least some of the dinosaurs had gizzard. Certainly we have proved that dinosaurs once existed, but there is still much more we are curious to learn. Perhaps you can dig up an old fossil bone one day yourself and add a bit of new information.