Final answer:
Propliopithecoidea is the catarrhine ancestor that predates the divergence of Cercopithecoidea (Old World monkeys) and Hominoidea (including apes and humans), believed to be the earliest such primate due to their dental formula.
Step-by-step explanation:
The catarrhine ancestor that appears before the split of Cercopithecoidea and Hominoidea is Propliopithecoidea. This superfamily of primates from the early Oligocene is related to Old World monkeys and is believed to represent the earliest catarrhine primate. The trait of having a dental formula of 2.1.2.3 is found in catarrhine primates and is present in propliopithecoids, suggesting that they are the earliest known members of this group.
Haplorrhini is divided into infraorders Simiiformes and Tarsiiformes. Platyrrhini, or New World monkeys, are found in Central and South America and have a prehensile tail. Catarrhini, found in Africa and Asia, include the superfamilies Cercopithecoidea and Hominoidea, the latter of which encompasses gibbons, great apes, and humans.