[2] The largest extant proboscidean is the African bush elephant, with a world record of size of 4 m (13.1 ft) at the shoulder and 10.4 t (11.5 short tons).

[4] By the late Eocene, some members of Proboscidea like Barytherium had reached considerable size, with an estimated mass of around 2 tonnes,[2] while others like Moeritherium are suggested to have been semi-aquatic.

[5] A major event in proboscidean evolution was the collision of Afro-Arabia with Eurasia, during the Early Miocene, around 18-19 million years ago allowing proboscideans to disperse from their African homeland across Eurasia, and later, around 16-15 million years ago into North America across the Bering Land Bridge.

[7] The Late Miocene saw major climatic changes, which resulted in the decline and extinction of many proboscidean groups such as amebelodontids and choerolophodontids.

[6] The earliest members of modern genera of Elephantidae appeared during the latest Miocene-early Pliocene around 6-5 million years ago.

The elephantid genera Elephas (which includes the living Asian elephant) and Mammuthus (mammoths) migrated out of Africa during the late Pliocene, around 3.6 to 3.2 million years ago.

[8] Over the course of the Early Pleistocene, all non-elephantid probobscideans outside of the Americas became extinct (including mammutids, gomphotheres and deinotheres), with the exception of Stegodon.

[10] At the end of the Early Pleistocene, around 800,000 years ago the elephantid genus Palaeoloxodon dispersed outside of Africa, becoming widely distributed in Eurasia.

Proboscideans underwent a dramatic decline during the Late Pleistocene as part of the Late Pleistocene megafauna extinctions, with all remaining non-elephantid proboscideans (including Stegodon, mastodons, and the American gomphotheres Cuvieronius and Notiomastodon) and Palaeoloxodon becoming extinct, with mammoths only surviving in relict populations on islands around the Bering Strait into the Holocene, with their latest survival being on Wrangel Island around 4,000 years ago.

Some members of the families Deinotheriidae, Mammutidae, Stegodontidae and Elephantidae are thought to have exceeded modern elephants in size, with shoulder heights over 4 metres (13 ft) and masses over 10 tonnes (22,000 lb), with average fully grown males of the mammutid "Mammut" borsoni having an estimated body mass of 16 tonnes (35,000 lb), making it one the largest and perhaps the largest land mammal ever, with a fragmentary specimen of the Indian elephant species Palaeoloxodon namadicus only known from a partial femur being speculatively estimated in the same study to have possibly reached a body mass of 22 tonnes (49,000 lb).

[2] As with other megaherbivores, including the extinct sauropod dinosaurs, the large size of proboscideans likely developed to allow them to survive on vegetation with low nutritional value.

These elephants likely grew smaller on islands due to a lack of large or viable predator populations and limited resources.