Which fossil group is characterized by an eye orbit fully enclosed by bone?

Question

Quizplus · Accepted Answer

Anthropoids, also known as primates, possess a complete postorbital bar, which fully encloses the eye orbit with bone. This is a key distinguishing feature of the group, which includes monkeys, apes, and humans. Adapids and omomyids are extinct early primates, while plesiadapiforms are non-primate mammals that lived during the Paleocene epoch. None of these groups exhibit a complete postorbital bar.

Which Fossil Group Is Characterized by an Eye Orbit Fully