119.WHERE DID THE DINOSAURS LIVE?
The best way we have of knowing what creatures were alive on this earth millions of years ago is from studying fossils. Fossils are animal and plant remains buried in the rocks. These remains, which have in most cases petrified (turned to stone), may be of shells, insects, leaves, bones, whole skeletons, or simply the tracks made by ancient animals on the shores of swamps.
From such evidence, scientists believe that dinosaurs roamed the earth about 180,000,000 years ago, and that they died out about 60,000,000 years ago. What fossils have been found that make these scientists believe this?The most common ones are bones, teeth, and claws. From these, skeletons can be reconstructed so we can tell how the body was built. In other cases, there have been trails and footprints.
118.WHERE DID ELEPHANTS ORIGINATE?
Thousands of years ago, many kinds of giant monsters roamed about the great forests then covering the earth. Even though these beasts were immense in size, they were not able to endure the hardships they had to undergo, brought about by changing climate and disappearance of food.
One by one they perished, until of all those huge animals, there are only two species remaining, the African and Asiatic elephants. The ancestors of the elephant were great monsters, known as “mammoths.” Their skeletons can be seen in museums, and they are quite awesome sights! Their bones have been dug up in caves and river beds in North America and Europe. In far-off Siberia, the carcass of one was found frozen hard in ice, perfectly preserved even to its eyes!
117.WHAT’S THE DIFFERENCE BETWEEN A TURTLE AND A TORTOISE?
Turtles, tortoises, and terrapins all belong to a group of four-legged reptiles that have hard outer shells, scaly skins, and horny beaks. Most people use the three words—turtle, tortoise, and terrapin—interchangeably. Scientists, however, sometimes make this distinction: a turtle is a sea reptile; a tortoise is a land reptile; and a terrapin is a fresh-water reptile.
It is correct to call all three turtles. They all breathe air through lungs and have shells that are made up of a “bony box” covered with horny plates or with soft skin. These shells are divided into two parts. One part covers the back; the other covers the underpart of the turtle’s body. Through the openings between the two parts, the turtle can thrust out its head, neck, tail, and legs.
