What extinct proboscidean from North America had low-crowned teeth and a flattened skull?

The extinct North American proboscidean with low-crowned teeth and a flattened skull was the American mastodon.

The American mastodon, Mammut americanum, was a large relative of elephants and mammoths that lived across North America from the late Miocene or Pliocene into the Late Pleistocene. It had a long, low skull and prominent tusks. Its cheek teeth were low-crowned and covered with blunt, cone-shaped cusps, a structure suited to crushing leaves, twigs, and other woody vegetation.

That tooth design reflects the mastodon’s typical habitat and diet. Unlike mammoths, which were mainly grazers with flatter, ridge-filled teeth adapted to abrasive grasses, mastodons were primarily browsers associated with forests, wetlands, and other wooded environments. Both males and females had tusks, although males’ tusks were generally larger.

The name mastodon comes from Greek roots meaning “breast tooth,” referring to the nipple-like cusps on its molars. Mastodons were not ancestral modern elephants and were only distant cousins. They disappeared from North America around 10,500–11,000 years ago, near the end of the Ice Age.