What is the major physical difference between old work monkeys and new world monkeys?

Answer & Explanation:
- One of the biggest differences between these two groups of monkeys is their tails. On one hand, some species of New World monkeys possess prehensile tails, meaning they can use their tails to grasp or hold on to objects. Their tails can aid these monkeys in finding and eating food in the canopy as well as moving amongst the trees, as their tails provide extra support and balance.

- On the other hand, Old World monkeys all have tails, but they lack the ability to grasp objects. However, some Old World monkeys have pads called ischial callosities surrounding their hind region. As these monkeys tend to spend more time on the ground than their arboreal New World counterparts, these calloused areas of skin provide support when they sit to feed or rest.

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