Azibius

Last updated

Azibius
Temporal range: Early to Middle Eocene
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Strepsirrhini
Family: Azibiidae
Genus: Azibius
Sudre, 1975
Species:
A. trerki
Binomial name
Azibius trerki
Sudre, 1975
Synonyms
  • Genus:
    • DralestesTabuce et al. 2004
    • TabeliaGodinot & Mahboubi 1994
  • Species:
    • Dralestes hammadaensisTabuce et al. 2004
    • Tabelia hammadaeGodinot & Mahboubi 1994

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 (known as strepsirrhines), although paleoanthropologists such as Marc Godinot have argued that they may be early simians (monkeys and apes). 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 , a fossil primate once thought to be the oldest known simian. 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.

Contents

Azibius trerki is the only named species, although a few teeth and a talus (ankle bone) of a larger, unnamed species (cf.  Azibius sp.) have also been found. A. trerki is estimated to have weighed 115 to 160 g (4.1 to 5.6 oz), while cf. Azibius sp. was larger, weighing approximately 630 to 920 g (22 to 32 oz). Based on the fragmentary fossils, both are thought to have been nocturnal and agile arboreal quadrupeds.

Evolutionary history and taxonomy

For years following its discovery, Azibius was difficult to classify. [1] Originally described by Jean Sudre in 1975 as a possible 'paromomyiform' (a type of plesiadapiform), A. trerki was also interpreted as a hyopsodontid by paleoanthropologist Frederick S. Szalay that same year. The following year, paleoanthropologist Philip D. Gingerich reclassified it as an adapid. 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). [1] [2]

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. [3] This latter view has gained increasing support with the reclassification of Algeripithecus (once considered a basal simian) as a closely related azibiid. The mandible of Algeripithecus indicates it had an inclined canine tooth, similar to that found in toothcombed primates. Although the anterior dentition of azibiids is unknown, they may have possessed a toothcomb, indicating an ancient stem lineage of lemuriform primates in Africa, [2] 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]

Tabelia hammadae, which was also considered to be one of the oldest known simians along with Algeripithecus, was shown to be a synonym of Azibius when more complete fossils were discovered at Gour Lazib between 2003 and 2009. Likewise, the second upper molar (M2) of Dralestes hammadaensis have been reinterpreted as being the upper fourth premolar (P4) of Azibius and has been considered a synonym. [6] 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. [7] In 2011, 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, thus reinforcing the strepsirrhine status favored by Tabuce et al. two years earlier. The tali morphology also differed radically from those of plesiadapiforms, confirming that azibiids are true primates. [9]

Remains of a second, unnamed species of Azibius, cf. Azibius sp., have been discovered in the HGL-50 layer at Gour Lazib. It is known for a few upper and lower teeth. These teeth are three times larger than those of A. trerki. A larger right talus has also been found, and is assumed to belong to this new species. [10]

Anatomy and physiology

All known azibiids were small-bodied primates. [11] A. trerki is estimated [lower-alpha 2] to have weighed between 115 and 160 g (4.1 and 5.6 oz), nearly twice the weight of the only other named azibiid, Algeripithecus, [2] and was comparable in size to a gray mouse lemur (Microcebus murinus). [11] The unnamed species, cf. Azibius sp., is estimated to have weighed 630 to 920 g (22 to 32 oz) and been comparable in size to a sportive lemur (Lepilemur). [11]

Azibius also had a short rostrum and very large orbits. [12]

Distribution

Azibius has only been found in the Glib Zegdou Formation of the Gour Lazib area in southwest Algeria. The Glib Zegdou Formation dates to the late early or early middle Eocene, particularly the late Ypresian or early Lutetian. [1] [13]

Behavior

Judging from the properties of its talus, Azibius was probably an arboreal quadruped, capable of leaping and climbing in trees, very similar to living cheirogaleid lemurs. [11] Based on what can be inferred from the maxillary remains, Azibius is thought to have had large eyes and extra vibrissae, which suggests it was nocturnal. [14]

Notes

  1. Talus bones are commonly used to taxonomically differentiate simians from "prosimian" primates in the fossil record. [8]
  2. Size estimates were calculated using regressions of the area of the first molar compared to living primates. [2]

Related Research Articles

Strepsirrhini Suborder of primates which includes lemurs, galagos, pottos and lorises

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.

Prosimian 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.

Haplorhini 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.

Adapidae Extinct family of primates

Adapidae is a family of extinct primates that primarily radiated during the Eocene epoch between about 55 and 34 million years ago.

Lemuriformes Infraorder of 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 Extinct order of primates

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.

Lorisoidea Superfamily of primates

Lorisoidea is a superfamily of nocturnal primates found throughout Africa and Asia. Members include the galagos and the lorisids. As strepsirrhines, lorisoids are related to the lemurs of Madagascar and are sometimes included in the infraorder Lemuriformes, although they are also sometimes placed in their own infraorder, LorisiformesGregory, 1915.

Toothcomb Dental structure found in some mammals, comprising a group of front teeth arranged in a manner that facilitates grooming

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.

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.

Evolution of lemurs 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.

Sublingua Secondary tongue found in some primates

The sublingua ("under-tongue") is a muscular secondary tongue found below the primary tongue in tarsiers and living strepsirrhine primates, which includes lemurs and lorisoids. Although it is most fully developed in these primates, similar structures can be found in some other mammals, such as marsupials, treeshrews, and colugos. This "second tongue" lacks taste buds, and in lemuriforms, it is thought to be used to remove hair and other debris from the toothcomb, a specialized dental structure used to comb the fur during oral grooming.

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).

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. It is predicted that this family existed from early to late Eocene, they lacked a teeth comb and were able to fully rotate their heads. It is also predicted that this family was a pivotal point for primate evolution, and that they were the cause for the adaption of a tooth comb.

<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.

Muangthanhinius is a genus of adapiform primate that lived in Asia during the late Eocene.

References

  1. 1 2 3 Godinot 2010, pp. 321–322.
  2. 1 2 3 4 Tabuce et al. 2009, p. 4088.
  3. Godinot 2006, pp. 461.
  4. Godinot 2006, pp. 461–462.
  5. Godinot 2006, pp. 454–455.
  6. Tabuce et al. 2009, pp. 4088–4089.
  7. Godinot 2010, pp. 322–323.
  8. Marivaux et al. 2011, p. 451.
  9. Marivaux et al. 2011, pp. 452–453.
  10. Marivaux et al. 2011, pp. 448–449.
  11. 1 2 3 4 Marivaux et al. 2011, p. 453.
  12. Tabuce et al. 2009, p. 4092.
  13. Tabuce et al. 2009, p. 4087.
  14. Tabuce et al. 2009, pp. 4090–4091.

Literature cited

  • 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.
  • 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.