At a certain point in history there were 350 species of proboscidiae on earth, although most of them were not elephants. Of these 350, all but the African and Asiatic elephants are now extinct. Although most of the proboscidiae had a trunk (a proboscis), a few did not have one as such. The moeritherium, for instance, one of the earliest proboscidiae, did not have one and was also relatively small.

Proboscidiae are related to seacows (manatees and dugongs) and hyraxes. Seacows are sea-mammals, as are whales.

The present elephantsí ancestors probably hesitated for a while between a life in the sea or a life on land (a bit like a hippopotamus). Telltale signs remain of this, for instance the fact that elephants are almost hairless, like sea-mammals. Furthermore, elephants can swim very well and they use their trunks as a snorkel, allowing them to stay underwater for a long time. Eventually, over 30 million years ago, proboscidiae chose a life on land.

The mammoth is the only other real member of the elephantidae. Therefore there used to be three elephant species: the African, the Asiatic, and the mammoth, a species that also lived in todayís Europe. The mammoth had big curved tusks and many types of mammoth had a lot of hair which kept them warm during the ice age. Complete mammoths are regularly found frozen in ice and perfectly preserved, for example in Russia, and skeletons of mammoths can be found in a number of museums. Mammoths are believed to have died out around 10,000 years ago. Changes in the climate turned the plains on which they lived into dense forests, which deprived the mammoths of sufficient food.