Walter Gray, age 13, of Boise, Idaho, for his question:

Did the dinosaurs have gizzards?

The last of the dinosaurs perished some 60 million years ago. So no living dinosaur was ever seen by a human being. 'that we know of the bulky beasts has been learned from their fossil remains.

Most fossil remains are bones. The softer parts of an animal's body soon decay. The flesh and internal organs are lost. Even a bone has to be large and sturdy to endure for 60 million years or more.

However, a smart scientist can learn a great deal about an extinct animal merely by studying the skeleton. Teeth and claws also tend to endure as fossils. The teeth can tell us whether the animal was a vegetarian. The claws may tell how he gathered his food and defended himself. Sometimes the fossil is a footprint or the imprint of the animal's skin, In the case of the dinosaurs, eggs and partly hatched skeletons of the young have been fossilized,

The place where the fossil skeleton was buried may also be important. The internal organs will decay. But if the remains have not been shuffled around by the changing earth, the decay from these organs and even the food may be found mixed with the rock and soil in the area of the creature's rib cage. In some cases, experts have been able to discover what kind of food was being digested when the fossilized animal met his doom. However, most of the dietary evidence applies to the fossils of animals who lived much later than the ancient dinosaurs,

On the basis of this evidence, then, you would not think there is much chance of d1acovoring much about the internal organs of a dinosaur, such as whether he digested his food with the help of a gizzard, Luckily, there is one clue which suggests that at least one type of dinosaur did have a gizzard. This clue comes .from the brontosaurus, whose name means thunder 1izard.

This fellow was one of the biggest of his kind. His complete skeleton suggests that he weighed about 37 tons. From his nose, down his long neck over the hump of his back to the tip of his whiplash tail he measured 70 feet, We think that Big Bronty lived in shallow water because he would have needed water to support his huge bulk. He was a vegetarian. This we know, because his large spoon shaped teeth could not have been used to tear flush. We can guess he lived on water weeds and tore them loose with the claw on each of his front feet.

This of course does not tell us a thing about how he digested his food, But the rocks among which one of these fossilized monsters was preserved suggest a clue. Among the debris from the region of the rib cage there were a number of highly polished silicous stones. It could be that these stones were worn smooth as they were used as millstones to grind up the food. On this evidence, most experts are almost certain that at least one type of dinosaur did have a gizzard.