Adapis

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Adapis
Temporal range: Bartonian-Priabonian, [1] 41.3–33.9  Ma
Adapis parisiensis.jpg
Adapis parisiensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Strepsirrhini
Family: Adapidae
Subfamily: Adapinae
Genus: Adapis
Cuvier, 1822
Type species
Adapis parisiensis
Cuvier, 1821
Species
  • A. bruniStehlin, 1912
  • A. collinsonaeHooker, 1986
  • A. parisiensisCuvier, 1821
  • A. sudreiGingerich, 1977

Adapis is an extinct adapiform primate from the Eocene of Europe. [2] [3] [4] [5] [6] [7] [8] [9] [10] While this genus has traditionally contained five species (A. magnus, A. bruni, A. collinsonae, A. parisiensis, and A. sudrei), recent research has recognized at least six morphotypes that may represent distinct species. [6] 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. [3] Given its 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. [6] [8]

Contents

Etymology and Naming

One etymology suggests that the word is derived from Greek : αa, 'without' and Greek : δάπιςdapis 'carpet', a reference to the assumed texture of its skin as it was considered a pachyderm. [11] However, since Pachydermata was first described in the eighteenth century, and 'adapis' was in use as a vernacular name for the hyrax during the sixteenth century, this etymology may be anachronistic. The more plausible etymology, which is referenced by Cuvier himself, is that, since he believed that the remains from the Paris region belonged to an extinct genus of pachyderms, he adopted Adapis, a non-scientific name that was "sometimes used for the Hyrax", which he considered related to Adapis. [12] Cuvier's source for the informal name was Conrad Gesner, Historiae animalium, I (Zurich, 1551), chapter on rabbits, p. 395. Gesner himself believed that both adapis and the Aramaic word from which he thought it was derived actually referred to the common rabbit.

Anatomy

A. parisiensis jaws Adapis parisiensis MHNT PAL 2013 0 1014 Esamps 46 Oligocene Filhol.jpg
A. parisiensis jaws

Adapis is considered a sexually dimorphic primate, in which males are generally larger in size than females; for example, one study found that compared to females, adult males of Adapis are 44%-56% larger in body weight, have 13-16% longer crania, and 13%-19% larger in canines. [2] Moreover, males of this genus have relatively broader skulls with more prominent nuchal and sagittal crests. [2] Interestingly, the canine dimorphism in Adapis is distinct from the form of canine dimorphism exhibited in Notharctus , another adapiform genus found in the Eocene of North America. [2] The fossil crania of Adapis exhibit relatively small orbits which suggests a diurnal activity pattern for the genus. [8] They also possess a tall sagittal crest and a strong postorbital constriction of the braincase in order to support massive temporalis muscles that facilitated powerful chewing. The dental anatomy of Adapis is characterized by dominant buccal shearing crests adapted for a folivorous and partially frugivorous diet. [9] The postcranial anatomy of Adapis suggests the taxon was adapted for climbing rather than leaping. For example, the femur shares many features in common with pottos and lorises, but not lemurs. [6] Adapis also has a very short astragalar neck and abbreviated distal elongation of the calcaneus. The ankle morphology of Adapis differs from that of notharctid taxa in its abbreviated astragalar neck and reduced distal aspect of the calcaneus. These features are also consistent with climbing instead of leaping. [10]

Taxonomic diversity

Adapis belongs to the family Adapidae. [5] While there is debate regarding the number of species of Adapis, the morphological variation in the humeri of Adapis suggests anywhere from four to six species could be represented in the genus. Traditionally, five species of Adapis have been recognized, including A. magnus, A. bruni, A. collinsonae, A. parisiensis, and A. sudrei. Recent research showed that some fossil humeri of Adapis exhibit morphology that is comparable to living active arboreal quadrupeds. [6] The evolutionary lineage from Adapis magnus to Adapis parisiensis exhibits reduced body size and canine size. [2]

Geographic and temporal range

Adapis was first discovered in southern France. [6] [8] Fossils are known from the early Eocene, [2] [3] [4] [5] [6] [7] [8] [9] [10] to the early Oligocene. The extinction of Adapis at the Eocoene-Oligiocene boundary has been considered to be the result of dramatic global cooling and drying. [2] While North American and European adapiforms did not have access to geographic refuge to evade the cooler and drier conditions in the Northern latitudes, adapiforms in Asia were able to retreat to southern geographic regions that did not experience severe cooling and drying, enabling their survival until the Miocene. [6]

History of discovery

The genus was first found and named by Georges Cuvier in 1821. This was the first Eocene primate ever discovered but was first mistakenly identified as an extinct genus of pachyderms. The true identity was not discovered until the 1870s where entire skulls were found in the Quercy region in southern France. [6] [7] Adapis and close relatives were also found in many fissure fillings in southern France. [6]

Paleobiology

While the average body weight of Adapis is estimated to be about 2.0 kg, the genus is represented by an extremely wide range of body size across species compared to other adapiform genera. A. parisiensis appears to have been a medium-sized (compared to the large-bodied A. magnus with an estimated body mass of 8.4-9.0 kg), [8] visually oriented, diurnal, sexually dimorphic arboreal folivore. [8] Examinations of the dental microwear reveal striations on molar wear facets A. magnus, which suggests complex, three-directional mandibular movement during mastication. Adapis has been interpreted as having a diurnal activity pattern due to its small orbits. [8] While some species of Adapis were mainly folivores, other species subsited on a diet that included some fruit. [9] Based on other anatomical features, Adapis is thought to have been a climber rather than a leaper, [6] and most likely had slow to medium slow locomotion. [4] Horizontal movement was also a possibly important means of locomotion. [10] In comparison with living primates, many researchers have considered the body size dimorphism in Adapis as indicative of a polygynous mating system. [2] However, other have interpreted the fossils A. parisiensis as indicative of monogamy, suggesting the taxon was predominately solitary with a small home range. Based on inner ear morphology, Adapis may have been more sensitive to high frequencies rather than low frequencies. This interpretation of inner-ear morphology has led some researchers to compare the social and activity behaviors of A. parisiensis to that of Perodicticus potto and Nycticebus coucang , which are extant primates that are solitary, nocturnal, and monogamous. Moreover, this morphology lends to the hypothesis that A. parisiensis had a small home range with sensitivity to high frequencies that do not broadcast over long distances. [4]

Related Research Articles

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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">Adapidae</span> 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.

<i>Aegyptopithecus</i> Extinct single-species genus of primate

Aegyptopithecus is an early fossil catarrhine that predates the divergence between hominoids (apes) and cercopithecids. It is known from a single species, Aegyptopithecus zeuxis, which lived around 38-29.5 million years ago in the early part of the Oligocene epoch. It likely resembled modern-day New World monkeys, and was about the same size as a modern howler monkey, which is about 56 to 92 cm long. Aegyptopithecus fossils have been found in the Jebel Qatrani Formation of modern-day Egypt. Aegyptopithecus is believed to be a stem-catarrhine, a crucial link between Eocene and Miocene fossils.

<i>Plesiadapis</i> Extinct genus of mammals

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.

<i>Notharctus tenebrosus</i> Extinct species of mammal

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.

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References

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