Primates are one group (order) of mammals that evolved about 65 million years ago (mya). The early primates were probably small tree-dwelling (arboreal) animals that hunted for insects at night. Today we recognize at least 167 living species in the order primates. We can classify these species (and the primate fossils we find) into two major groups (suborders): prosimians (at least 38 species) and anthropoids (at least 129 species). Prosimians include lemurs (Lemuriformes), galagos and lorises (Lorisiformes) and tarsiers (Tarsiiformes). Anthropoids include New World monkeys (Platyrrhini; from South America), Old World monkeys (from Africa and Asia), apes and humans (Catarrhini). However, some scientists feel that tarsiers should be classified as anthropoids rather than as prosimians.

Prosimians

The first primates to evolve were prosimians. These early primates split into several subgroups about 55 mya. One lineage (see graph) gave rise to Lorisiformes and Lemuriformes, and the other lineage gave rise to Tarsiiformes and the...