Final answer:
The Propliopithecoidea group, found in the Fayum, Egypt, represent the first cercopithecoids with bilophodont molars and an adaptation to terrestrial quadrupedalism, making them early Old World monkeys during the Oligocene epoch.
Step-by-step explanation:
The cercopithecoids were indeed among the first primates to exhibit certain distinctive features, such as bilophodont molars and terrestrial quadrupedalism. However, for the sentence in question, a precise genus or species must be specified to complete the statement. In this context, referring to 'cercopithecoids' we might be discussing early monkeys during the Oligocene epoch, specifically the Propliopithecoidea group. The Propliopithecoidea, based on archaeological finds at Fayum, Egypt, have been suggested as the earliest Old World monkeys. These primates displayed dental and skeletal traits that were precursors to modern cercopithecoids, including bilophodont molar patterns and terrestrial adaptations for quadrupedal movement.