- Most early mammals didn't have armor or size to protect them...
多数早期哺乳动物 没有护甲来保护它们 - yet just like in today's forests...
但就像今天的森林中一样 - danger was never far away.
危险永远不会离得太远 - The discarded skin of their ancient adversary.
它们古老对手的蜕皮 - The snake.
蛇 - Snakes evolved around the same time as the first true mammals.
蛇的进化时间 与第一批真正的哺乳动物大致相同 - They lost the arms and legs of their reptilian ancestors
它们失去了爬行动物祖先的四肢