検索キーワード： 制作 "Charles River Editors" 進化

The Mesozoic Era, which lasted from about 252 to 66 million years ago, is divided into three periods, the Triassic, Jurassic, and Cretaceous. During this era, one type of life came to dominate the planet more completely and for a longer period than had been seen before or since; this was the Age of Reptiles. Beginning in the Triassic but especially in the Jurassic period, reptiles came to dominate the oceans, the land and even the skies.

The evolutionary path from the original primates to modern man is a long one and has taken many twists and turns, but naturally, as the fossil record grows, scientists gain a more complete understanding of our own mental and physical history in terms of genetics and anatomy. However, the correct order and relationships of the various specimen types are difficult to pin down.

The early history of Earth covers such vast stretches of time that years, centuries, and even millennia become virtually meaningless. Instead, paleontologists and scientists who study geochronology divide time into periods and eras. The current view of science is that Earth is around 4.6 billion years old, and the first four billion years of its development are known as the Precambrian period.