海豚,是由陆生哺乳类演化而成的,据信应为类似偶蹄目的种类.现在的海豚骨骼中,位於骨盆处有两只棒状的骨头被认为是退化的后肢.它们约在5000万年前回到海中生活.（在鲸类王国里,要数海豚家族——海豚科的种类最多了,全世界已知共有30多种.有的种类虽名叫“鲸”,如虎鲸、伪虎鲸,其实也是海豚家族中的成员.海豚指鲸目齿鲸亚目海豚科成员,白鳍豚也是海豚科的.）
The porpoise,is lives by the land,according to what is believed should for the similar artiodactyl goal type which the mammalia evolution becomes.In the present porpoise skeleton,is located the pelvis place to have two clavate bones to consider is the degenerated hind legs.They approximately return to in the sea in 50,000,000 years ago to live.
括号内容——(In the whale class kingdom,the factor porpoise family - - porpoise branch type have been most,the world known altogether has 30 many kinds of.Although some types the name is called “the whale”,like the killer whale,the false killer whale,also are actually in the porpoise family's members.The porpoise refers to the whale item odontoceti porpoise branch member,the lipotes vexillifer also is the porpoise branch.)
