Pleistocene Giants: The Great Herds of Ice Age North America

Five iconic herds (and solitary giants) that thundered the interior:

1. Woolly Mammoths — Matriarchal herds ≤100, shaggy, curved tusks, grazed steppe-tundra from Beringia to Great Lakes.
2. American Mastodons — Smaller, straighter tusks, browser herds ≤100, preferred spruce forests and wetlands.
3. Giant Ground Sloths — Megatherium: 4 tons, 6 m, solitary, claws for stripping trees. Not a herd animal.
4. Saber-Toothed Cats — Smilodon: ambush solo hunters, 300 kg, 18-cm canines, targeted megafauna.
5. Dire Wolves — Pack hunters ≤20, bone-crushing jaws, competed with cats for mammoth/mastodon kills.

All extinct by ~11,000 BP—climate shift, human hunting, or both. Their bones still surface in Midwest loess and La Brea tar pits.