The herd has its own defense against the cheetahs' blistering speed. 兽群自有 对抗猎豹惊人速度的防御策略
others evolved to feed on the grazers. 另一些哺乳动物 则进化为以食草动物为食
But just as some mammals evolved to feed on the grass, 但在一些哺乳动物 进化成以草为食的同时
Mammals have truly conquered the grassy plains... 哺乳动物真正征服了草原
their huge numbers the most obvious sign of this exceptional success. 它们庞大的数量 就是巨大成功的最明显的标志