Plesiadapiformes ("

Adapid Adapidae is a family of extinct primates that primarily radiated during the Eocene epoch between about 55 and 34 million years ago. Adapid systematics and evolutionary relationships are controversial, but there is fairly good evidence from the ...

-like" or "near Adapiformes") is a group of

Primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter including ...

, a sister of the Dermoptera. While none of the groups normally directly assigned to this group survived, the group appears actually not to be literally extinct (in the sense of having no living descendants) as the remaining

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter includin ...

s (the crown primates or "Euprimates") appear to be derived Plesiadapiformes, as a sister of e.g. the

Carpolestidae Carpolestidae is a family of primate-like Plesiadapiformes that were prevalent in North America and Asia from the mid Paleocene through the early Eocene. Typically, they are characterized by two large upper posterior premolars and one large lower ...

. The term Plesiadapiformes may still be used for all primates which are not crown primates, but this usage is

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

. When the crown primates are cladistically granted, it becomes an obsolete junior synonym to primates. '' Purgatorius'' is believed to be a basal Plesiadapiformes. Plesiadapiformes first appear in the fossil record between 65 and 55 million years ago, although many were extinct by the beginning of the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

. They may have been the first mammals to have finger nails in place of claws. In 1990, K.C. Beard attempted to link the Plesiadapiformes with the order Dermoptera. They proposed that paromomyid ''Phenacolemur'' had digital proportions of the fossil indicated gliding habits similar to that of colugos. In the following simplified cladogram, the crown primates are found to be highly derived Plesiadapiformes, possibly as sister of the Plesiadapoidea. The crown primates are cladistically granted here into the Plesiadapiformes, and the 'plesiadapiformes' become a junior synonym of the primates. With this tree, the plesiadapiformes are not literally extinct (in the sense of having no surviving descendants). The crown primates are also called "Euprimates" in this context. Alternatively, in 2018, the plesiadapiform were proposed to be more related to Dermoptera, or roughly corresponding to Primatomorpha with both Dermoptera and the primates emerging within this group. Also in a 2020 paper, the primates and Dermoptera were jointly considered sister to the plesiadapiform Purgatoriidae, resulting in the following phylogenetic tree. Traditionally, they were regarded as a separate extinct order of

Primatomorpha The Primatomorpha are a proposed mirorder of mammals containing the flying lemurs (order Dermoptera or colugos) and lemurs (Strepsirrhini, adapiformes and lemuriformes). However, notably, the haplorhini are sister to the lemurs, together form ...

, but it now appears that groups such as the extant primates and/or the Dermoptera have emerged in the group. One possible classification table of plesiadapiform families is listed below. *PLESIADAPIFORMES ** Family Micromomyidae ** Superfamily Paromomyoidea *** Family Paromomyidae *** Family Picromomyidae *** Family Palaechthonidae *** Family Microsyopidae ** Superfamily Plesiadapoidea *** Family

*** Family Chronolestidae *** Family Picrodontidae *** Family Plesiadapidae *** Family Saxonellidae

References

External links

Mikko's Phylogeny Archive
{{Taxonbar, from=Q426505 Mammal orders Paleocene first appearances Eocene extinctions Paraphyletic groups