Jerry Bogan, age 8, of Winnipeg Man., Canada, for his question:

Which was the biggest dinosaur of prehistoric times?

During the Age of Reptiles Most of the earth's animals were dinosaurs. There were big ones, small ones, medium sized ones and many, many different kinds. Only a few of them left their bones for us to find in the ground. We shall, no doubt, find more and more of them. Maybe we shall find the remains of a dinosaur who was bigger than the biggest one we now have so far as we know the biggest dinosaur was the brontosaurus. His name means the thunder lizard, though most likely brontosaurus was not a fierce, thundering animal. From his nose to the end of his long tail he measured 75 feet and the giant was a vegetarian. He lived in marshy swamps and fed mostly on shaggy water weeds.