Adapiforms are known from the fossil record only, and it is unclear whether they form a monophyletic or paraphyletic group.

[4] In 2009, Franzen and colleagues placed the newly described genus Darwinius in the "Adapoidea group of early primates representative of early haplorhine diversification" so that, according to these authors, the adapiforms would not be within the Strepsirrhini lineage as hitherto assumed but qualify as a stem "missing link" between Strepsirrhini and Haplorrhini.

[6] Boyer et al. found that the crown Strepsirrhini likely emerged deep in the Adapiformes tree, possibly as sister of a group which include e.g. Aframonius and Notharctidae.

[7] The Adapiformes are thus found not to be literally extinct (in the sense of having no living descendants), and becomes a junior synonym to the Strepsirrhini.

[10] Rose (1995) suggests that early adapiforms and omomyiforms shared a common ancestor dating to the Thanetian age.