Which characteristics are associated with Catarrhines?

The characteristics associated with Catarrhines include diurnal habits and ischial callosities. Catarrhines, which comprise Old World monkeys, apes, and humans, are predominantly active during the day (diurnal) as opposed to being nocturnal. This trait distinguishes them from some other primate groups.

Ischial callosities refer to the tough, callused areas on the sitting bones of some primates that provide added comfort during prolonged sitting, which is more commonly observed in some Catarrhine species. This feature is particularly prominent among certain Old World monkeys and is adaptive for their lifestyle.

In contrast to the other choices, nocturnal habits are primarily a characteristic of some prosimians, flat noses are not exclusive to Catarrhines as they can also appear in other primate groups, and long prehensile tails are associated with New World monkeys, which belong to a different group called Platyrrhines. Together, these distinctions help clarify why diurnal habits and ischial callosities are the defining characteristics of Catarrhines.