Omomyiformes

Omomyiformes are an extinct group of early primates or primate-like mammals known from fossil sites dating to the Paleocene and early to middle Eocene. They were small-bodied and are commonly interpreted as having been nocturnal, a trait suggested by relatively large eye orbits in many specimens. Their dentition and skull morphology indicate insectivorous or omnivorous diets, and their anatomy distinguishes them from other contemporary primate groups.

In traditional classifications, Omomyiformes are placed as a primitive or stem group within the broader primate lineage, often discussed in relation to Adapiformes, another large extinct group from the same era. The exact phylogenetic position of omomyiforms is debated: some analyses place them as closer to the haplorhines (the group that includes tarsiers and anthropoids), while others view them as a separate stem lineage. This ambiguity is part of the broader discussion about the early divergence of haplorhines and strepsirrhines in primate evolution.

The fossil record for omomyiforms is best documented in North America, Europe, and Asia, with the first appearances in the late Paleocene and later diversification during the early to middle Eocene. Their lineage largely disappears by the middle to late Eocene, a period that also sees the rise of more modern primate groups. Omomyiforms remain significant for understanding the early evolutionary steps that led to later haplorhine primates and the broader narrative of primate origins.