They appeared shortly after the dinosaurs disappeared, 65 million years ago, at a time when whales still had legs, and they come from a rebellious little puffer fish faction -- oblige me a little Kipling-esque storytelling here.
它们是在恐龙消失之后很短时间内出现的， 6500万年前，那时候鲸类还长着脚， 它们从河豚类群中“反叛”了出来—— 请允许我在这里套用下吉卜林讲故事的方式。