Plesiadapiformes (" Adapid-like" or "near

Adapiformes Adapiformes is a group of early primates. Adapiforms radiated throughout much of the northern continental mass (now Europe, Asia and North America), reaching as far south as northern Africa and tropical Asia. They existed from the Eocene to the M ...

") 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 huma ...

, 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 including huma ...

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 lo ...

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

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

. When the crown primates are

cladistically Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

granted, it becomes an obsolete junior synonym to primates. ''

Purgatorius ''Purgatorius'' is a genus of seven extinct eutherian species typically believed to be the earliest example of a primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 66 million years ago. The first rem ...

'' 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 (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

. They may have been the first mammals to have

finger nails A nail is a claw-like plate found at the tip of the fingers and toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer. ...

in place of

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

s. 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 Plesiadapoidea was an extinct superfamily of primates that existed during the Paleocene and 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 Paleogen ...

. The crown primates are

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 Micromomyidae (Micromomids) is a family of extinct plesiadapiform mammals that include some of the earliest known primates. The family includes five genera that lived from the Paleocene epoch into the early Eocene epoch. Micromomyids first appea ...

** Superfamily Paromomyoidea *** Family

Paromomyidae Paromomyidae is a family of mammals that may include the earliest 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 in ...

*** Family Picromomyidae *** Family Palaechthonidae *** Family Microsyopidae ** Superfamily

*** Family

*** Family Chronolestidae *** Family Picrodontidae *** Family

Plesiadapidae Plesiadapidae is a family of plesiadapiform mammals related to primates known from the Paleocene and Eocene of North America, Europe, and Asia. Plesiadapids were abundant in the late Paleocene, and their fossils are often used to establish the a ...

*** Family Saxonellidae

References

External links

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