At various times mixodectids have been compared to rodents, "
insectivores", and, most frequently, dermopterans (colugos or "flying lemurs"). A 2025 study based on new postcranial fossils estimated that mixodectids are euarchontans within or near the clade Primatomorpha (which contains primates and colugos). Their exact affinities among early euarchontans is still debated.
Torrejonian (Middle Paleocene) mixodectids had a dental set-up similar to the oldest
plagiomenids, and were sometimes regarded as an ancestral or
sister group of the latter. For many years
Elipdophorus, the oldest plagiomenid, was classified as a member of Mixodectidae, but it was finally regarded as more closely related to plagiomenids in the 1970s based on its specialized teeth. Though the relation between Mixodectidae and other early placental mammals from the "insectivore-primate transition" remain unclear, clearly a number of the archaic mixodectid dental features seem to foreshadow the more derived conditions of plagiomenids. Furthermore, the
postcranial skeleton of
Mixodectes shows
arboreal specialization similar to those of
plesiadapids and
dermopterans, supporting their inclusion within
Euarchonta. == See also ==