There were large animals on all continents. The Americas had giant sloths, mastodons, and camels. Australia had creatures like the Diprotodon (a hippopatamus sized wombat like creature, the Procoptodon (a 500 pound giant kangaroo), and the Megalania (a 23 foot monitor lizard). Europe had mammoths, giant polar bears, and several varieties of rhinoceros, and Asia has/had elephants and hippos.
Except for Asia and Africa, these creatures have been wiped out. The cause is still being debated but generally it is believed it was due to human hunting, climate changes, and/or the additive pressures from both.