 A greater disparity in extinction timings is apparent in island megafaunal extinctions that lagged nearby continental extinctions by thousands of years; examples include the survival of woolly mammoths on Wrangel Island, Russia, until 3700 BP, and the survival of ground sloths in the Antilles, the Caribbean, until 4700 cal BP.The Australian megafaunal extinctions occurred approximately 30,000 years earlier than the hypothetical Younger Dryas event.The megafaunal extinction pattern observed in North America poses a problem for the bolide impact scenario, since it raises the question why large mammals should be preferentially exterminated over small mammals or other vertebrates.