Which primate characteristic is associated with having well-developed arboreal adaptations?

The presence of a postorbital bar is indeed associated with well-developed arboreal adaptations in primates. The postorbital bar is a bony structure that encircles the eye socket and helps provide structural support for the eyes, which is beneficial for animals that navigate a three-dimensional arboreal environment. This feature is characteristic of many primates, indicating their adaptations for living in trees, where depth perception and visual acuity are essential for activities like jumping between branches and assessing distances.

Primates with well-developed arboreal adaptations tend to have forward-facing eyes, which enhance their stereoscopic vision, allowing for better depth perception crucial for navigating in complex forest canopies. The postorbital bar aids in stabilizing the eye position, making it easier for these primates to judge distances accurately as they move through their environment.