Azibiidae

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Azibiidae
Temporal range: 52–46  Ma
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Early to Middle Eocene
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Strepsirrhini
Infraorder: incertae sedis
Family: Azibiidae
Gingerich, 1976
Genera

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 (known as strepsirrhines), although paleoanthropologists such as Marc Godinot have argued that they may be early simians (monkeys and apes). It includes the genera Azibius and Algeripithecus , the latter of which was originally considered the oldest known simian, not a strepsirrhine.

Contents

Originally described as a type of plesiadapiform (an extinct group of arboreal mammals considered to be a sister group to the primate clade), its fragmentary remains have been interpreted as a hyopsodontid (a type of extinct condylarth), an adapid (an extinct type of adapiform primate from Europe), and a macroscelidid (elephant shrews). Less fragmentary remains discovered between 2003 and 2009 demonstrated a close relationship between Azibius and Algeripithecus. Descriptions of the talus (ankle bone) 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. Likewise, if azibiids are simians, it would support the hypothesis that simians originated in Africa instead of Asia.

Azibiids were small-bodied primates, with Algeripithecus minutus weighing between 65 and 85 g (2.3 and 3.0 oz), Azibius trerki weighing approximately 115 and 160 g (4.1 and 5.6 oz), and an unnamed species of Azibius being notably larger, weighing an estimated 630 to 920 g (22 to 32 oz).

Evolutionary history

Although the taxonomy is disputed, [1] morphological evidence suggests that azibiids were one of the earliest offshoots of the early primate lineage leading to living lemuriforms, which excluded other adapiform primates. [2] According to Tabuce et al., the mandible of Algeripithecus indicates it had an inclined canine tooth, similar to that found in crown lemuriforms (extant strepsirrhines). Although the anterior dentition of azibiids is unknown, they may have possessed a toothcomb (a specialized dental structure found in lemuriforms), indicating an ancient stem lineage of lemuriform primates in Africa, [3] possibly descended from an early Asian branch of adapiforms [4] such as a primitive branch of cercamoniines predating Donrussellia (one of the oldest European adapiforms). [5] However, the uncertainty about the presence or absence of a true toothcomb in azibiids makes it difficult to determine if they are stem or crown lemuriforms. [2] According to Tabuce et al., Azibiids belong to an Afro–Arabian clade of stem lemuriform primates, including successive sister taxa such as djebelemurids (including Djebelemur and 'Anchomomys' milleri ) and a group that includes Plesiopithecus and crown lemuriforms. [6] However, if azibiids are simians, as originally suggested with Algeripithecus, then they demonstrate an ancient simian lineage and their evolutionary divergence on the continent of Africa, [7] contrary to the competing view that simians first evolved in Asia. [8]

General phylogeny of strepsirrhines [9]
Primates  
  Haplorhines  

Simians (monkeys, apes, and humans)

Tarsiers

Omomyiforms

  Strepsirrhines  

Adapiforms

†Azibiids

Djebelemurids

Plesiopithecus

Lemuriforms (lemurs, lorises, and galagos)

Holarctic clade
Afro-Arabian
clade
An Afro-Arabian clade of early strepsirrhines is thought to have given rise modern lemurs, lorises, and galagos. Azibiid taxonomy is still disputed.

Taxonomy

The first species, Azibius trerki, was originally described by Jean Sudre in 1975 as a possible 'paromomyiform' (a type of plesiadapiform, an extinct group of arboreal mammals considered to be a sister group to the primate clade), but was also interpreted as a hyopsodontid (a type of extinct condylarth) by paleoanthropologist Frederick S. Szalay that same year. The following year, paleoanthropologist Philip D. Gingerich reclassified it as an adapid (an extinct type of adapiform primate from Europe). Throughout the 1990s and 2000s, debates over its classification continued, with some researchers suggesting it might be related to macroscelidids (elephant shrews), while others supported initial interpretations as adapids or plesiadapiforms (particularly carpolestids). [10]

In 2006, paleoanthropologist Marc Godinot favored a relationship between Azibius and simians, but tentatively suggested Azibius may be more closely related to toothcombed primates, which include all extant strepsirrhines. [11] This latter view has gained increasing support with the reclassification of Algeripithecus (once considered a basal simian) as a closely related azibiid. Additional fossil teeth and the maxilla (upper jaw) of both genera discovered between 2003 and 2009 helped demonstrate their relationship. Based on the same fossil finds, Tabelia—which was also considered to be one of the oldest known simians along with Algeripithecus—is also now considered to be a synonym of Azibius. Also, the third and fourth lower premolars (P3 and P4) distinguish azibiids from carpolestids, while the upper fourth premolar (P4) matches what was thought to be the second upper molar (M2) of Dralestes hammadaensis, another suspected plesiadapiform [12] or genus of azibiid. [13] Specimens of Dralestes are now recognized as being either Azibius and Algeripithecus, and Tabuce et al. claimed that Dralestes was a synonym of Azibius in 2009. [12] However, in 2010, Godinot cautiously suggested that Dralestes may be a synonym of Algeripithecus based on a blade-like premolar. He also reasserted his view that Algeripithecus was a simian based on its upper molar morphology and hypothesized that this applied to all azibiids, favoring his earlier view that they may be early simians instead of stem lemuriforms. [1] The argument for strepsirrhine affinities was strengthened in 2011 when Marivaux et al. published an interpretation of recently discovered talus bones [lower-alpha 1] found at Gour Lazib, which they claimed were more similar to those of living strepsirrhines and extinct adapiforms, not simians. The tali morphology also differed radically from those of plesiadapiforms, confirming that azibiids are true primates. [15]

Anatomy and physiology

All known azibiids were small-bodied primates. [16] The body mass of Algeripithecus minutus was estimated [lower-alpha 2] between 65 and 85 g (2.3 and 3.0 oz), [10] equivalent in size to a hairy-eared dwarf lemur (Allocebus trichotis) or the brown mouse lemur (Microcebus rufus). [16] Azibius trerki was estimated to weigh between 115 and 160 g (4.1 and 5.6 oz), [10] comparable in size to a gray mouse lemur (Microcebus murinus). An unnamed species, cf. Azibius sp., was larger, weighing between 630 and 920 g (22 and 32 oz), making it similar in size to sportive lemurs (Lepilemur). [16]

Distribution

Both Azibius and Algeripithecus have only been found in the Glib Zegdou Formation of the Gour Lazib area in Algeria. The Glib Zegdou Formation dates to the late early or early middle Eocene. [8] Two upper molars found in Chambi, Tunisia, which were originally associated with Djebelemur martinezi (another suspected stem lemuriform), may instead represent another primate more closely related to Algeripithecus. [17]

Notes

  1. Talus bones are commonly used to taxonomically differentiate simians from "prosimian" primates in the fossil record. [14]
  2. Size estimates were calculated using regressions of the area of the first molar compared to living primates. [10]

Related Research Articles

<span class="mw-page-title-main">Strepsirrhini</span> Suborder of primates

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.

<span class="mw-page-title-main">Prosimian</span> Obsolete primate taxon

Prosimians are a group of primates that includes all living and extinct strepsirrhines, as well as the haplorhine tarsiers and their extinct relatives, the omomyiforms, i.e. all primates excluding the simians. They are considered to have characteristics that are more "primitive" than those of simians.

<span class="mw-page-title-main">Haplorhini</span> Suborder of primates

Haplorhini, the haplorhines or the "dry-nosed" primates, is a suborder of primates containing the tarsiers and the simians, as sister of the Strepsirrhini ("moist-nosed"). The name is sometimes spelled Haplorrhini. The simians include catarrhines, and the platyrrhines.

<span class="mw-page-title-main">Lemuriformes</span> Infraorder of primates

Lemuriformes is the sole extant 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.

<span class="mw-page-title-main">Simian</span> Infraorder of primates

The simians, anthropoids, or higher primates are an infraorder of primates containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders New World monkeys (Platyrrhini) and Catarrhini, the latter of which consists of the family Cercopithecidae and the superfamily Hominoidea.

<span class="mw-page-title-main">Toothcomb</span> Dental structure found in some mammals

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.

Altiatlasius is an extinct genus of mammal, which may have been the oldest known primate, dating to the Late Paleocene from Morocco. The only species, Altiatlasius koulchii, was described in 1990.

<i>Darwinius</i> Extinct genus of primates

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.

Karanisia is an extinct genus of strepsirrhine primate from middle Eocene deposits in Egypt.

Bugtilemur is an extinct genus of Strepsirhine primate belonging to the adapiform family Ekgmowechashalidae.It is represented by only one species, B. mathesoni, which was found in the Chitarwata Formation of Pakistan.

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.

<span class="mw-page-title-main">Evolution of lemurs</span> History of primate evolution on Madagascar

Lemurs, primates belonging to the suborder Strepsirrhini which branched off from other primates less than 63 million years ago, evolved on the island of Madagascar, for at least 40 million years. They share some traits with the most basal primates, and thus are often confused as being ancestral to modern monkeys, apes, and humans. Instead, they merely resemble ancestral primates.

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).

Djebelemuridae is an extinct family of early strepsirrhine primates from Africa. It consists of five genera. The organisms in this family were exceptionally small, and were insectivores. This family dates to the early to late Eocene. Although they gave rise to the crown strepsirrhines, which includes today's lemurs and lorisoids, they lacked the toothcomb that identifies that group.

<i>Afrasia djijidae</i> Eocene fossil primate from Myanmar

Afrasia djijidae is a fossil primate that lived in Myanmar approximately 37 million years ago, during the late middle Eocene. The only species in the genus Afrasia, it was a small primate, estimated to weigh around 100 grams (3.5 oz). Despite the significant geographic distance between them, Afrasia is thought to be closely related to Afrotarsius, an enigmatic fossil found in Libya and Egypt that dates to 38–39 million years ago. If this relationship is correct, it suggests that early simians dispersed from Asia to Africa during the middle Eocene and would add further support to the hypothesis that the first simians evolved in Asia, not Africa. Neither Afrasia nor Afrotarsius, which together form the family Afrotarsiidae, is considered ancestral to living simians, but they are part of a side branch or stem group known as eosimiiforms. Because they did not give rise to the stem simians that are known from the same deposits in Africa, early Asian simians are thought to have dispersed from Asia to Africa more than once prior to the late middle Eocene. Such dispersals from Asia to Africa also were seen around the same time in other mammalian groups, including hystricognathous rodents and anthracotheres.

Plesiopithecus is an extinct genus of early strepsirrhine primate from the late Eocene.

<span class="mw-page-title-main">Evolution of primates</span> Origin and diversification of primates through geologic time

The evolutionary history of the primates can be traced back 57–90 million years.

Afradapis is a genus of adapiform primate that lived during the Late Eocene. The only known species, Afradapis longicristatus, was discovered in the Birket Qarun Formation in northern Egypt in 2009. While its geographic distribution is confined to Afro-Arabia, Afradapis belongs to the predominantly European adapiform family Caenopithecidae. This taxonomic placement is supported by recent phylogenetic analyses that recover a close evolutionary relationship between Afradapis and adapiforms, including Darwinius. While adapiforms have been noted for their strepsirrhine-like morphology, no adapiform fossil possesses the unique anatomical traits to establish an ancestor-descent relationship between caenopithecids and living strepsirrhines. It ate leaves and moved around slowly like lorises.

The Amphipithecidae were simian primates that lived in Late Eocene and Early Oligocene. Fossils have been found in Myanmar, Thailand, and Pakistan. The limited fossil evidence is consistent with, but not exclusive to, arboreal quadrupedalism. In other words, the species may have moved about in trees on four legs, but not with regular leaping as seen in later simians.

References

  1. 1 2 Godinot 2010, pp. 322–323.
  2. 1 2 Tabuce et al. 2009, p. 4093.
  3. Tabuce et al. 2009, pp. 4092–4093.
  4. Godinot 2006, pp. 461–462.
  5. Godinot 2006, pp. 454–455.
  6. Tabuce et al. 2009, p. 4091.
  7. Godinot & Mahboubi 1992, p. 326.
  8. 1 2 Tabuce et al. 2009, p. 4087.
  9. Tabuce et al. 2009, pp. 4091–4092.
  10. 1 2 3 4 Tabuce et al. 2009, p. 4088.
  11. Godinot 2006, pp. 461.
  12. 1 2 Tabuce et al. 2009, pp. 4088–4089.
  13. Godinot 2010, p. 320.
  14. Marivaux et al. 2011, p. 451.
  15. Marivaux et al. 2011, pp. 452–453.
  16. 1 2 3 Marivaux et al. 2011, p. 453.
  17. Seiffert et al. 2010, pp. 371–372.

Literature cited

  • Godinot, M.; Mahboubi, M. (1992). "Earliest known simian primate found in Algeria". Nature. 357 (6376): 324–326. doi:10.1038/357324a0. PMID   1589034.
  • Godinot, M. (2006). "Lemuriform origins as viewed from the fossil record". Folia Primatologica. 77 (6): 446–464. doi:10.1159/000095391. PMID   17053330.
  • Godinot, M. (2010). "Chapter 19: Paleogene Prosimians". In Werdelin, L.; Sanders, W.J (eds.). Cenozoic Mammals of Africa. University of California Press. ISBN   978-0-520-25721-4.
  • Marivaux, L.; Tabuce, R.; Lebrun, R.; Ravel, A.; Adaci, M.; Mahboubi, M.H.; Bensalah, M. (2011). "Talar morphology of azibiids, strepsirhine-related primates from the Eocene of Algeria: Phylogenetic affinities and locomotor adaptation". Journal of Human Evolution. 61 (4): 447–457. doi:10.1016/j.jhevol.2011.05.013. PMID   21752425.
  • Seiffert, E.R.; Simons, E.L.; Fleagle, J.G.; Godinot, M. (2010). "Chapter 22: Paleogene Anthropoids". In Werdelin, L.; Sanders, W.J (eds.). Cenozoic Mammals of Africa. University of California Press. ISBN   978-0-520-25721-4.
  • Tabuce, R.; Marivaux, L.; Lebrun, R.; Adaci, M.; Bensalah, M.; Fabre, P. -H.; Fara, E.; Gomes Rodrigues, H.; Hautier, L.; Jaeger, J. -J.; Lazzari, V.; Mebrouk, F.; Peigne, S.; Sudre, J.; Tafforeau, P.; Valentin, X.; Mahboubi, M. (2009). "Anthropoid versus strepsirhine status of the African Eocene primates Algeripithecus and Azibius: Craniodental evidence". Proceedings of the Royal Society B: Biological Sciences. 276 (1676): 4087–4094. doi:10.1098/rspb.2009.1339. PMC   2821352 . PMID   19740889.