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Plesiadapiformes (cohort Unguiculata, order Primates) An extinct suborder that comprises the families Paramomyidae, Plesiadapidae, Carpolestidae, and Picrodontidae, which are the earliest known primates and flourished during the Palaeocene. Most are known only from the most fragmentary remains, mainly of teeth and parts of jaws, though a few skulls and even partial skeletons are known, and apart from the fact that they are primates their relationship to later forms is uncertain. Probably most were too specialized to have given rise to later primates, despite their geologically ancient occurrence.