It was descended from the Columbian mammoth (M. columbi) of mainland North America, which are suggested to have colonised the islands around 250–150,000 years ago.

The species became extinct around 13,000 years ago, co-inciding with major environmental change and the arrival of humans in the Channel islands.

[2] In 1994 the National Park Service called in scientists to inspect an uncovered, unidentified skeleton found on the northeast coast of Santa Rosa Island.

It is suggested that their Columbian mammoth ancestors colonised the islands either around 250,000 or 150,000 years ago, when sea levels were considerably lower than they are today.

[12] The limb bones of the species show isometric growth (preserving length-width ratio) from juveniles to adults, similar to those of living African elephants.

[12] During the Last Glacial Period, the mega-island of Santa Rosae is thought to have been forested with coniferous trees of cypress, douglas fir and pine.

This time coincides with the reduction of the area of Santa Rosae as a result of rising sea level, the arrival of humans in the Channel Islands (as evidenced by Arlington Springs Man) and climatic change resulting in the decline of the previously dominant conifer forest ecosystems and expansion of scrub and grassland, possibly induced by wildfires.