Final answer:
The two infraorders of Catarrhini are Cercopithecoidea (Old World monkeys) and Hominoidea (apes and humans). Their ancestors likely include the Propliopithecoidea, which show the earliest evidence of dental features characteristic of modern catarrhines.
Step-by-step explanation:
The infraorder Catarrhini, part of the Haplorrhini, is divided into two superfamilies: Cercopithecoidea and Hominoidea. The Cercopithecoidea comprises Old World monkeys, which include cheek pouch monkeys and leaf-eating monkeys, classified under the subfamilies Cercopithecinae and Colobinae, respectively. The Hominoidea includes tailless primates such as gibbons, great apes, and humans. A common ancestor of catarrhines is the prehistoric Propliopithecoidea, which possessed similar dental formulation found in modern catarrhines, suggesting it represents the earliest catarrhine primate.
The propliopithecoids are believed to have evolved in Africa. This is supported by the presence of the dental formula 2.1.2.3 in the fossil records of Propliopithecus, which is characteristic of present-day catarrhines.