请用英语说出恐龙的有关知识

恐龙是出现于二亿四千五百万年前，并繁荣于六千五百万年前结束的中生代爬行动物。或为恐龙和与它同一时代的蛇颈龙、翼龙等的模糊总称。恐龙在6500万年前白垩纪结束的时候突然全部消失，成为地球生物进化史上的一个谜，这个谜至今仍无人能解。地球过去的生物，均被记录在化石之中。中生代的地层中，即曾发现许多恐龙的化石。其中可以见到大量或呈现各式各样形状的骨骼。但是，在紧接着的新生代地层中，却完全看不到恐龙的化石，由此推知恐龙在中生代时一起灭绝了。恐龙种类多，体形和习性相差也大。其中个子大的，可以有几十头大象加起来那么大；小的，却跟一只鸡差不多。就食性来说，有温顺的草食者和凶暴的肉食者，还有荤素都吃的杂食性恐龙。
Dinosaurs appeared in two hundred and forty-five million years ago, sixty-five million years ago and prosperity at the end of the Mesozoic reptiles. Fuzzy general or dinosaurs, and with it the same era plesiosaurs, pterosaurs and other. The dinosaurs 65 million years ago when the end of the Cretaceous period suddenly disappeared, become a mystery to the evolutionary history of life on earth, still no one can solve this mystery. Creatures of the earth in the past, were recorded in the fossils. The Mesozoic strata, that many dinosaur fossils have been found. One can see a lot of presents every kind of shape or bones. But in the ensuing Cenozoic strata, but can not see the dinosaur fossils, and thus to infer with the extinction of the dinosaurs in the Mesozoic. Many kinds of dinosaurs, shape and habits also big difference. Which is great, there are dozens of elephants together so much; small, but with almost a chicken. On the diet, docile herbivores and ferocious carnivorous and omnivorous dinosaur, meat and vegetables to eat.