Nacholapithecus

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Nacholapithecus
Exhibition of bone finds at the Kyoto University Museum, Kyoto, Japan

Exhibition of bone finds at the Kyoto University Museum , Kyoto , Japan

Temporal occurrence
middle Miocene
15 to 14 million years
Locations
Systematics
Monkey (anthropoidea)
Old World Monkey (Catarrhini)
Human (Hominoidea)
incertae sedis
Nacholapithecus
Scientific name
Nacholapithecus
Ishida , Kunimatsu , Nakatsukasa & Nakano , 1999
species
  • Nacholapithecus kerioi

Nacholapithecus is an extinct genus of primates thatoccurredin Kenya around 15 million years ago during the Middle Miocene . The assignment of the genus to a certain family within the superfamily of the human species was described in the first description as "uncertain" (" incertae sedis ").

Naming

The name of the genus was derived in 1999 from the location near the village Nachola in the area of ​​today's Samburu County in Kenya and from the Greek word πίθηκος ( pronounced píthēkos in ancient Greek : "monkey"). The epithet of the type species and so far the only scientifically described species of the genus, Nacholapithecus kerioi , honors a deceased village chief of Nachola named Kerio. Nacholapithecus kerioi therefore means "Kerios monkey from Nachola".

The finds from the fossil deposit near Nachola, which has been investigated since 1982, had previously been assigned to the genus Kenyapithecus . However, according to the first description of Nacholapithecus, they differ so much from Kenyapithecus wickeri and Kenyapithecus africanus that they could not only be assigned to an additionally defined species, but also to a newly introduced genus.

Initial description

In the first description by a group of Japanese researchers, a partially preserved skeleton (archive number KNM-BG 35250), consisting of the upper jaw and lower jaw , most elements of the spine and numerous bones in the fore, was named as the holotype of the genus and at the same time the type species Nacholapithecus kerioi - and hind legs. The large number of related fossils enabled - in comparison with other, similarly old fossils - a fairly reliable reconstruction of the size and other characteristics of Nacholapithecus kerioi . In the unusually short first description, which was only two printed pages long , the authors limited themselves to the statement that the individual recovered from the Aka-Aiteputh formation was a large animal with pronounced sexual dimorphism , comparable to a steppe baboon . Some features of the teeth of the upper and lower jaw were named, but not differentiated from other genera. The only statement about the bones below the head was: "forelimb appreciably longer than hindlimb" (front leg considerably longer than hind leg).

features

It was not until 2003 and 2004 that more detailed descriptions of the bone finds were published. According to this, the type specimen, as evidenced by the large canine teeth, is the fossils of a male. His back injury is similar to that of the genus Proconsul and show no signs pointing to a for apes typical suspensorische locomotion suggest. Furthermore, similarities in the structure of the jaws and the dentition with Kenyapithecus and Morotopithecus were mentioned.

The arms and especially the hands of Nacholapithecus kerioi are noticeable differences in comparison with the almost equally old genera already mentioned : In relation to the legs, both the bones of the arms and the finger bones are very long. This points to a specialized mode of locomotion in the branches of trees, which is not known in a comparable form either from Proconsul heseloni and Proconsul nyanzae or from tree-dwelling monkeys living today. According to the analyzes, this construction of the arms makes it easier to climb trees around the trunk, but has a negative effect on the stability of the spine; consequently there must have been a special selection pressure that promoted this unusual construction.

The assumed way of life specializing in climbing is also reflected in the construction of the legs. In a study, the authors came to the conclusion that Nacholapithecus kerioi moved relatively slowly and - as evidenced by the morphology of its grasping feet - was less pronounced (horizontally on all four extremities) than other Miocene primates.

Tribal classification

The phylogenetic classification of Nacholapithecus is unclear; not least because an almost complete skeleton of Nacholapithecus kerioi has survived, but mostly only partial skeletons of other species from the same geological epoch have been preserved. The unusually briefly justified removal of the Nachola finds from the genus Kenyapithecus took place in 1999 a few days before a revision of the naming of Miocene primates from Africa was proposed in connection with the first description of Equatorius . This reorganization included the fossils that had been placed up to then on Kenyapithecus africanus in the genus Equatorius and suggested that the Nachola finds also be included in Equatorius .

The assignment of the genus Nacholapithecus to the Proconsulidae family, proposed in 2009, was taken up a year later in the first description by Saadanius , but was not given permanent attention. After another reading include Nacholapithecus and Equatorius in the family of great apes (hominids) to extinct subfamily Afropithecinae.

literature

  • Yoshihiro Sawada, Martin Pickford , Tetsumaru Itaya et al .: K-Ar ages of Miocene Hominoidea (Kenyapithecus and Samburupithecus) from Samburu Hills, Northern Kenya. In: Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science. Volume 326, No. 6, 1998, pp. 445-451, doi: 10.1016 / S1251-8050 (98) 80069-4
  • Yutaka Kunimatsu, Hidemi Ishida et al .: Maxillae and associated gnathodental specimens of Nacholapithecus kerioi, a large-bodied hominoid from Nachola, northern Kenya. In: Journal of Human Evolution. Volume 46, No. 4, 2004, pp. 365-400, doi: 10.1016 / j.jhevol . 2003.12.008
  • Yasuhiro Kikuchi, Yoshihiko Nakano et al .: Functional morphology and anatomy of cervical vertebrae in Nacholapithecus kerioi, a middle Miocene hominoid from Kenya. In: Journal of Human Evolution. Volume 62, No. 6, 2012, pp. 677-695, doi: 10.1016 / j.jhevol.2012.03.002
  • Yasuhiro Kikuchi, Masato Nakatsukasa et al .: Morphology of the thoracolumbar spine of the middle Miocene hominoid Nacholapithecus kerioi from northern Kenya. In: Journal of Human Evolution. Volume 88, 2015, pp. 25-42, doi: 10.1016 / j.jhevol.2015.09.003
  • Yasuhiro Kikuchia, Masato Nakatsukasa et al .: Sacral vertebral remains of the Middle Miocene hominoid Nacholapithecus kerioi from northern Kenya. In: Journal of Human Evolution. Volume 94, 2016, pp. 117–125, doi: 10.1016 / j.jhevol.2016.03.006
  • Naomichi Ogihara, Sergio Almécija et al .: Carpal bones of Nacholapithecus kerioi, a Middle Miocene Hominoid From Northern Kenya. In: American Journal of Physical Anthropology. Volume 160, No. 3, 2016, pp. 469-482, doi: 10.1002 / ajpa.22984
  • Yutaka Kunimatsu, Masato Nakatsukasa et al .: Loss of the subarcuate fossa and the phylogeny of Nacholapithecus. In: Journal of Human Evolution. Volume 131, 2019, pp. 22-27, doi: 10.1016 / j.jhevol.2019.03.004

Web links

See also

Individual evidence

  1. ↑ a b c Hidemi Ishida, Yutaka Kunimatsu, Masato Nakatsukasa and Yoshihiko Nakano: New Hominoid Genus from the Middle Miocene of Nachola, Kenya. In: Anthropological Science. Volume 107, No. 2, 1999, pp. 189–191, doi: 10.1537 / ase.107.189 , full text (PDF)
  2. ^ Hidemi Ishida, Yutaka Kunimatsu, Tomo Takano, Yoshihiko Nakano, and Masato Nakatsukasa: Nacholapithecus skeleton from the Middle Miocene of Kenya. In: Journal of Human Evolution. Volume 46, No. 1, 2004, pp. 69-103, doi: 10.1016 / j.jhevol.2003.10.001
  3. ↑ Masato Nakatsukasa, Yutaka Kunimatsu, Yoshihiko Nakano, Tomo Takano and Hidemi Ishida: Comparative and functional anatomy of phalanges in Nacholapithecus kerioi, a Middle Miocene hominoid from northern Kenya. In: Primates. Volume 44, No. 4, 2003, pp. 371-412, doi: 10.1007 / s10329-003-0051-y
  4. ↑ Masato Nakatsukasa, Yutaka Kunimatsu et al .: Hind limb of the Nacholapithecus kerioi holotype and implications for its positional behavior. In: Anthropological Science. Volume 120, No. 3, 2012, pp. 235–250, doi: 10.1537 / ase.120731 , full text (PDF)
  5. ↑ Steve Ward, Barbara Brown, Andrew Hill, Jay Kelley, and Will Downs: Equatorius: A New Hominoid Genus from the Middle Miocene of Kenya. In: Science . Volume 285, No. No. 5432, 1999, pp. 1382-1386, doi: 10.1126 / science.285.5432.1382
  6. ↑ Masato Nakatsukasa and Yutaka Kunimatsu: Nacholapithecus and its importance for understanding hominoid evolution. In: Evolutionary Anthropology. Volume 18, No. 3, 2009, pp. 103-119, doi: 10.1002 / evan.20208
  7. ↑ Steven C. Ward, Dana L. Duren: Middle and late Miocene African hominoids. In: Walter Carl Hartwig: The Primate Fossil Record. Cambridge University Press, New York 2002, p. 388, ISBN 0-521-66315-6