Their results showed convincingly that among living animals , whales are most closely related to the even - toed hoofed mammals , or artiodactyls , a group whose members include camels , hippopotamuses , pigs and ruminants such as cows 他们的结果证明，在现生哺乳类中，鲸豚与偶蹄类最亲近；骆驼、河马、猪及牛羊等反刍动物都属于偶蹄类。
