Fossil omomyids are found in North America, Europe & Asia, making it one of two groups of Eocene primates with a geographic distribution spanning holarctic continents, the other being the adapids (family Adapidae).

Early representatives of the Omomyidae and Adapidae appear suddenly at the beginning of the Eocene (56 mya) in North America, Europe, and Asia, and are the earliest known crown primates.

Features that characterize many omomyids include large orbits (eye sockets), shortened rostra and dental arcades, loss of anterior premolars, cheek teeth adapted for insectivorous or frugivorous diets, and relatively small body mass (i.e., less than 500 g).

However, by the late middle Eocene (about 40 mya), some North American omomyids evolved body masses in excess of 1 kg (2.2 lb) and frugivorous or folivorous diets.

Omomyids as a group also lack most of the derived specializations of living tarsiers, such as extremely enlarged orbits (Shoshonius is a possible exception), a large supra-meatal foramen for an anastomosis between the posterior auricular and middle meningeal circulation (again, Shoshonius is a possible exception, but the contents of the foramen in this extinct taxon are unknown), and extreme postcranial adaptations for leaping.