Here's a breakdown:
* Common ancestor: Old and new world monkeys share a common ancestor that lived approximately 40 million years ago.
* Divergence: After that, their evolutionary paths diverged, resulting in two distinct groups with different characteristics and geographical distributions.
* Old World Monkeys: These monkeys evolved in Africa and Asia. They have downward-facing nostrils, lack prehensile tails, and have cheek pouches for storing food.
* New World Monkeys: These monkeys evolved in the Americas. They have sideways-facing nostrils, prehensile tails (which they use for grasping and swinging), and lack cheek pouches.
In summary: While they are both primates, old world and new world monkeys belong to different infraorders:
* Old World Monkeys: Cercopithecoidea
* New World Monkeys: Platyrrhini
This means they are distant relatives, having diverged from a common ancestor long ago and developing distinct features.