Purgatorius may not be a primate as an extinct sister to the rest of the Dermoptera[8] or a separate, more basal stem pan-primate branch.

Plesiadapiformes first appear in the fossil record between 65 and 55 million years ago,[9][10] although many were extinct by the beginning of the Eocene.

[12] In the following simplified cladogram, the crown primates are classified as highly derived Plesiadapiformes, possibly as sister of the Plesiadapoidea.

[13][14][15] Also in a 2020 paper, the primates and Dermoptera were jointly considered sister to the plesiadapiform Purgatoriidae, resulting in the following phylogenetic tree.

[16] Rodentia (rodents) Lagomorpha (rabbits, hares, pikas) Scandentia (treeshrews) †Purgatoriidae Dermoptera (colugos) Primates †Plesiadapiform s.s.