They ate woody vegetation — the twigs, bark, and leaves of trees and shrubs — rather than grasses.

The patchy woodland and shrub communities of the late Pleistocene Pacific Northwest, transitioning from the cold-adapted tundra and steppe of the glacial maximum to the conifer forest of the Holocene, would have provided suitable browse for mastodons in many areas.

The wetland and pond environments associated with the Manis site — a small lake or pond that was slowly filling in with organic sediment — would have attracted mastodons seeking water and the aquatic and riparian vegetation that grew around wet areas.

The mastodon that became the Manis specimen was in exactly this kind of environment when it died.