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.
Omomyidae is a group of early primates that radiated during the Eocene epoch between about 55 to 34 million years ago (mya). Fossil omomyids are found in North America, Europe & Asia making it one of two groups of Eocene primates with a geographic distribution spanning holarctic continents, the other being the adapids. Early representatives of the Omomyidae and Adapidae appear suddenly at the beginning of the Eocene in North America, Europe, and Asia, and are the earliest known crown primates.
Lemuriformes is an infraorder of primate that falls under the suborder Strepsirrhini. It includes the lemurs of Madagascar, as well as the galagos and lorisids of Africa and Asia, although a popular alternative taxonomy places the lorisoids in their own infraorder, Lorisiformes.
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.
Notharctus tenebrosus was an early primate from the early Eocene, some 54–38 million years ago. Its fossil was found by Ferdinand V. Hayden in 1870 in southwestern Wyoming. When first found, Notharctus tenebrosus was thought to be a small pachyderm due to the concentration of pachyderm fossils in the area. However, after Walter W. Granger's discovery of a nearly complete skeleton, also in Wyoming, it was firmly established as a primate. Notharctus tenebrosus most resembles modern-day lemurs, although they are not directly related.
Europolemur klatti was a medium to large size adapiformes primate that lived on the continent of Europe from the middle to early Eocene. One possible relative to this species is Margarita stevensi, whose type specimen is about the size of a white-footed sportive lemur. Characteristic of most adapines are the reduced or absence of a paraconid and morphology of the paracristid. These and a few other features are synapomorphies that were used to link E. klatti with Leptadapis priscus and Microadapis sciureus, as well as Smilodectes.
Smilodectes is a genus of adapiform primate that lived in North America during the middle Eocene. It possesses a post-orbital bar and grasping thumbs and toes. Smilodectes has a small cranium size and the foramen magnum was located at the back of the skull, on the occipital bone.
Hesperolemur is a genus of adapiform primate that lived in the middle Eocene of southern California. It is an immigrant taxa which appears to be most closely related to the earlier European forms of Cantius. It was approximately 4.5 kilograms (9.9 lb) in weight and was the last surviving notharctine species, probably because of its position in the refugia that existed in southern California during the climate deterioration at the end of the middle Eocene. There are no later taxa that appear to have derived from Hesperolemur.
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.
Europolemur is a genus of adapiformes primates that lived in Europe during the middle Eocene.
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.
Cantius is a genus of adapiform primate that lived in North America and Europe during the early Eocene.
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.
Azibius is an extinct genus 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. Originally described as a type of plesiadapiform, its fragmentary remains have been interpreted as a hyopsodontid, an adapid, and a macroscelidid. Less fragmentary remains discovered between 2003 and 2009 demonstrated a close relationship between Azibius and Algeripithecus, a fossil primate once thought to be the oldest known simian. Descriptions of the talus in 2011 have helped to strengthen support for the strepsirrhine status of Azibius and Algeripithecus, which would indicate that the evolutionary history of lemurs and their kin is rooted in Africa.
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.
Donrussellia is a genus of adapiform primate that lived in Europe during the early Eocene. It is considered one of the earliest adapiforms, with D. magna sharing features with Cantius.
Copelemur is a genus of adapiform primate that lived in North America during the early Eocene.
Sivaladapis is a genus of adapiform primate that lived in Asia during the middle Miocene.
