距今二亿年左右至六、七千万年这段漫长的时间,地质学上称之为中生代。中生代爬行动物特别繁盛,它们种类繁多,形态变化万千,空间分布非常广泛,统治了地球上陆、海、空各个领域。在空中有各种翼龙,在海洋里有鱼龙、蛇颈龙……,真是一个恐龙世界。想到恐龙,因为它带有“恐”字,人们总以为它们是一种可怕的庞然大物。自地球上开始出现生命以来,在陆地上的确没有比恐龙更大的动物了。最大的蜥脚类恐龙,当它活着的时候,体重可达50吨。最长的恐龙,从头到尾全长达26～27米。但恐龙并不都是巨大的,最 About 200 million years ago to six or seven million years of this long time, geologically known as Mesozoic. Mesozoic reptiles are particularly prosperous, they are diverse, morphological changes, spatial distribution is very extensive, ruled the earth land, sea and air in all fields. There are a variety of pterosaurs in the air, there are fish in the ocean, plesiosaurus ..., is really a dinosaur world. Think of dinosaurs, because it carries the word “fear”, people always think they are a terrible monster. Since the beginning of life on Earth, there have been no more animals on land than dinosaurs. The largest sauropod dinosaurs, when it is alive, weighs up to 50 tons. The longest dinosaur, from start to finish the full length of 26 to 27 meters. But dinosaurs are not huge, most