The era dinosaurs began many millions years ago, in the middle of the Triassic. But still scientists continue to investigate and study life and activity of these unusual beings with enthusiasm.
Instruction
1. According to assumptions of scientists, the first dinosaurs appeared about 180-190 million years ago, and about 60-70 million years ago completely died out. It is considered that dinosaurs were reptiles therefore had to come from beings, similar to which lived to them. Reptiles represent a separate class of animals, the following is characteristic of them: they can live on the earth, warm-blooded, have a peculiar heart, the body of most of them is covered with scales.
2. The first reptiles appeared on Earth many years prior to emergence of dinosaurs, they resembled amphibians, could live both on the land, and in water spaces. Eggs of a reptile were laid only on the earth. The cubs who hatched from egg had lungs and legs, could breathe freely air and ate various insects. Over the years reptiles became stronger and more. Some beings reminded turtles, others – big lizards. They ate plants, had thick legs, the big heads and short tails.
3. The first dinosaurs resembled very much the primogenitors – reptiles which went on hinder legs and reminded lizards rather. Scientists consider that the first dinosaurs were rather small, of the size of a turkey-cock, moved on hinder legs. Some species of dinosaurs remained small, others grew up long and heavy. Some of them reached in height of 2-3 meters, there were even several six-meter dinosaurs who weighed several tons. They had the small heads and also stupid short teeth which were suitable only for chewing of plants. There lived such beings in marshy and low-lying places.
4. Further there came other period of life of reptiles. Some species of herbivorous dinosaurs became so huge that hardly could hold themselves on four legs on the land. Therefore began to spend the most part of time on swamps and the rivers. The largest species of dinosaurs – brontosaurs reached in height of 24 meters and about 35 tons weighed. These beings owing to the climate change on Earth which deprived of dinosaurs of food and habitats disappeared.