1. Natural Dispersal: Monkeys, which are native to Africa and Asia, may have naturally dispersed to the new world through land bridges or island hopping. It is theorised that during periods of lower sea levels, the continents were more closely connected, allowing monkeys to move between Africa and South America.
2. Human Introduction: Another possibility is that old-world monkeys were introduced by humans during prehistoric times. Early human navigators from Africa or Asia may have intentionally or unintentionally transported monkeys across the Atlantic Ocean on boats or rafts. These animals could have escaped or been released, leading to the establishment of monkey populations in the new world.
However, it is essential to note that there is limited fossil evidence or other direct proof of old world monkeys inhabiting the new world in prehistoric times. The presence of old world monkeys in the new world is primarily observed through the current distribution of monkeys such as the Capuchin and howler monkeys, which are believed to have common ancestors with old-world monkeys.