Euprimates

Euprimates is a clade in primatology that includes all living primates (the crown group) and their fossil relatives that are more closely related to living primates than to the earlier plesiadapiforms. The term, meaning “true primates,” is used to distinguish this lineage from more primitive, non-primate mammal groups that resemble primates but lie outside Euprimates.

Dating and early evolution: The euprimate fossil record begins in the Paleocene to early Eocene, roughly 56 to 45 million years ago. Early euprimates are known from Europe and North America and are represented by groups such as Adapiformes and Omomyiformes. They display several primate-derived traits, including grasping hands and feet, nails rather than claws, forward-facing eyes with stereoscopic vision, and changes in skull and dental morphology that indicate enhanced sensory processing and a more versatile diet.

Among the earliest splits within Euprimates, the fossil record often treats adapiforms and omomyiforms as stem euprimates, with adapiforms bearing more strepsirrhine-like traits and omomyiforms bearing more haplorhine-like traits. Later, the crown primate lineage diverged into two major subgroups: Strepsirrhini (lemurs and lorises) and Haplorhini (tarsiers and the simians). The haplorhines further gave rise to anthropoids, which include monkeys, apes, and humans.

Impact and significance: Euprimates are central to understanding primate evolution, including the origin of key traits related to diet, locomotion, and brain development. The group also informs debates about the timing of divergences among major primate lineages and their geographic patterns in the early fossil record.