Strepsirrhini or Strepsirhini is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Collectively they are referred to as strepsirrhines. Also belonging to the suborder are the extinct adapiform primates which thrived during the Eocene in Europe, North America, and Asia, but disappeared from most of the Northern Hemisphere as the climate cooled. Adapiforms are sometimes referred to as being "lemur-like", although the diversity of both lemurs and adapiforms does not support this comparison.
Adapidae is a family of extinct primates that primarily radiated during the Eocene epoch between about 55 and 34 million years ago.
Plesiadapis is one of the oldest known primate-like mammal genera which existed about 58–55 million years ago in North America and Europe. Plesiadapis means "near-Adapis", which is a reference to the adapiform primate of the Eocene period, Adapis. Plesiadapis tricuspidens, the type specimen, is named after the three cusps present on its upper incisors.
Adapiformes is a group of early primates. Adapiforms radiated throughout much of the northern continental mass, reaching as far south as northern Africa and tropical Asia. They existed from the Eocene to the Miocene epoch. Some adapiforms resembled living lemurs.
Necrolemur is a small bodied omomyid with body mass estimations ranging from 114 grams to 346 grams. Necrolemur’s teeth feature broad basins and blunt cusps, suggesting their diet consisted of mostly soft fruit, though examination of microwear patterns suggests that populations from lower latitudes also consumed insects and gums. While they do not sport a true tooth comb like modern lemurs, microwear patterns on their lower incisors suggest they engaged in fur grooming behaviors. Like tarsiers, Necrolemur had large, front-facing, close set eyes and were likely nocturnal. Analysis of cranial and postcranial fossils by paleontologists suggest members of the family Omomyidae, including the genus Necrolemur, possessed highly specialized adaptations for leaping.
Shoshonius is an extinct genus of omomyid primate that lived during the Eocene. Specimens identified as Shoshonius have been found exclusively in central Wyoming and the genus currently includes two species, Shoshonius cooperi, described by Granger in 1910, and Shoshonius bowni, described by Honey in 1990.
Notharctinae is an extinct subfamily of primates that were common in North America during the early and middle Eocene. The six genera that make up the group contain species that are among the most primitive of the adapiform group, which is one of the most primitive groups of primates. The evolutionary history of this subfamily has been comparatively well documented and has been used to argue for evolutionary gradualism. Though it is generally accepted that adapiforms gave rise to modern day lemurs and lorises, it is not currently known which branch of Adapiformes these living species are most closely related to. Notharctines became extinct in the middle Eocene, most likely because of a combination of factors including climatic change and competition with other North American primates.
Altanius is a genus of extinct primates found in the early Eocene of Mongolia. Though its phylogenetic relationship is questionable, many have placed it as either a primitive omomyid or as a member of the sister group to both adapoids and omomyids. The genus is represented by one species, Altanius orlovi, estimated to weigh about 10–30g from relatively well-known and complete dental and facial characteristics.
Pelycodus is an extinct genus of adapiform primate that lived during the early Eocene (Wasatchian) period in Europe and North America, particularly Wyoming and New Mexico. It is very closely related to Cantius and may even be its subgenus. It may also have given rise to the Middle Eocene Uintan primate Hesperolemur, although this is controversial. From mass estimates based on the first molar, the two species, P. jarrovii and P. danielsae, weighed 4.5 kg and 6.3 kg respectively and were frugivores with an arboreal, quadrupedal locomotion.
A toothcomb is a dental structure found in some mammals, comprising a group of front teeth arranged in a manner that facilitates grooming, similar to a hair comb. The toothcomb occurs in lemuriform primates, treeshrews, colugos, hyraxes, and some African antelopes. The structures evolved independently in different types of mammals through convergent evolution and varies both in dental composition and structure. In most mammals the comb is formed by a group of teeth with fine spaces between them. The toothcombs in most mammals include incisors only, while in lemuriform primates they include incisors and canine teeth that tilt forward at the front of the lower jaw, followed by a canine-shaped first premolar. The toothcombs of colugos and hyraxes take a different form with the individual incisors being serrated, providing multiple tines per tooth.
Darwinius is a genus within the infraorder Adapiformes, a group of basal strepsirrhine primates from the middle Eocene epoch. Its only known species, Darwinius masillae, lived approximately 47 million years ago based on dating of the fossil site.
Adapis is an extinct adapiform primate from the Eocene of Europe. While this genus has traditionally contained five species, recent research has recognized at least six morphotypes that may represent distinct species. Adapis holds the title of the first Eocene primate ever discovered. In 1821, Georges Cuvier, who is considered to be the founding father of paleontology, discovered Adapis in fissure fillings outside of Paris, France. Given it's timing and appearance in the fossil record, Cuvier did not recognize the primate affinities of Adapis and first described it as a small extinct pachyderm; only later in the 19th century was Adapis identified as a primate.
Rooneyia viejaensis is a relatively small primate belonging to the extinct monotypic genus Rooneyia. Rooneyia viejaensis is known from the North American Eocene of the Sierra Vieja of West Texas; the species is only known from the type specimen. The lack of additional fossils at this time makes it difficult to hypothesize where and how Rooneyia may have evolved. The minimal wear upon the molar teeth of the specimen has led to the assumption that the type specimen is that of a young adult. Rooneyia does not consistently fall within any one group of fossil or extant primates.
Algeripithecus is an extinct genus of early fossil primate, weighing approximately 65 to 85 grams. Fossils have been found in Algeria dating from 50 to 46 million years ago.
Mesopropithecus is an extinct genus of small to medium-sized lemur, or strepsirrhine primate, from Madagascar that includes three species, M. dolichobrachion, M. globiceps, and M. pithecoides. Together with Palaeopropithecus, Archaeoindris, and Babakotia, it is part of the sloth lemur family (Palaeopropithecidae). Once thought to be an indriid because its skull is similar to that of living sifakas, a recently discovered postcranial skeleton shows Mesopropithecus had longer forelimbs than hindlimbs—a distinctive trait shared by sloth lemurs but not by indriids. However, as it had the shortest forelimbs of all sloth lemurs, it is thought that Mesopropithecus was more quadrupedal and did not use suspension as much as the other sloth lemurs.
Cantius is a genus of adapiform primates from the early Eocene of North America and Europe. It is extremely well represented in the fossil record in North America and has been hypothesized to be the direct ancestor of Notharctus in North America. The evolution of Cantius is characterized by a significant increase in body mass that nearly tripled in size. The earliest species were considered small-sized and weighed in around 1 kg, while the later occurring species were considered medium-sized and likely weighed in around 3 kg. Though significantly smaller, the fossil remains discovered of the various species of Cantius have striking similarities to that of Nothartcus and Smilodectes. It is likely Cantius relied on arboreal quadrupedal locomotion, primarily running and leaping. This locomotor pattern comparable to that of extant lemurs, which has fostered the hypothesis that Cantius and other strepsirrhine adapiforms may have a close phylogenetic affinity to living lemurs.
Azibiidae is an extinct family of fossil primate from the late early or early middle Eocene from the Glib Zegdou Formation in the Gour Lazib area of Algeria. They are thought to be related to the living toothcombed primates, the lemurs and lorisoids, although paleoanthropologists such as Marc Godinot have argued that they may be early simians. It includes the genera Azibius and Algeripithecus, the latter of which was originally considered the oldest known simian, not a strepsirrhine.
Djebelemur is an extinct genus of early strepsirrhine primate from the late early or early middle Eocene period from the Chambi locality in Tunisia. Although they probably lacked a toothcomb, a specialized dental structure found in living lemuriforms, they are thought to be a related stem group. The one recognized species, Djebelemur martinezi, was very small, approximately 100 g (3.5 oz).
Plesiopithecus is an extinct genus of early strepsirrhine primate from the late Eocene.
Sivaladapis is a genus of adapiform primate that lived in Asia during the middle Miocene.
