Nakalipithecus
| Nakalipithecus Temporal range:
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| Top and side views of the Nakalipithecus holotype, a jawbone | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Primates |
| Suborder: | Haplorhini |
| Infraorder: | Simiiformes |
| Superfamily: | Hominoidea |
| Family: | Hominidae |
| Genus: | †Nakalipithecus Kunimatsu et al., 2007 |
| Species: | †N. nakayamai
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| Binomial name | |
| †Nakalipithecus nakayamai Kunimatsu et al., 2007
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Nakalipithecus nakayamai is an extinct species of great ape from the Late Miocene of Nakali, Kenya, about 9.9–9.8 million years ago. It is known from a jawbone and 11 isolated teeth, and the specimen is presumed female as the teeth are similar in size to those of female gorillas and orangutans. It is one of only three Late Miocene great apes known from Africa, the others Samburupithecus and Chororapithecus. Nakalipithecus seems to have inhabited a sclerophyllous woodland environment.
Taxonomy
Nakalipithecus was first described from a jawbone, KNM-NA46400, and eleven isolated teeth excavated in 2005 by a team of Japanese and Kenyan researchers in mud flow deposits in the Nakali area of northern Kenya's former Rift Valley Province, hence the genus name Nakalipithecus ("Nakali ape"). The species name is in honour of the late Japanese geologist Katsuhiro Nakayama who worked on the expedition. The specimen dates to about 9.9–9.8 million years ago in the Late Miocene.[1]
It is debated if great apes evolved in Africa or Eurasia given the abundance of early fossil apes species in the latter and the paucity in the former, despite all modern great apes except the orangutan being known from Africa. The first Miocene African ape was discovered in 1997, Samburupithecus, and the only others known are Nakalipithecus and Chororapithecus. It is unclear how Nakalipithecus is related to other apes. It is possible these Late Miocene African apes were stem great apes closely related to the last common ancestor of all modern African apes, which existed about 9–8 million years ago.[1]
| Hominidae |
| Two hypotheses on Nakalipithecus taxonomy[2] |
Nakalipithecus and Ouranopithecus exhibit many similarities with each other, but Nakalipithecus has more basal (primitive) traits, which could indicate that it was the ancestor or closely related to the ancestor of Ouranopithecus. Ouranopithecus, in turn, is postulated to be closely related to australopithecines and the human line. This would show that apes evolved in Africa. However, evidence of common ancestry can also be interpreted as convergent evolution, with similar dental adaptations caused by inhabiting a similar environment, though Ouranopithecus seems to have consumed more hard objects than Nakalipithecus.[1] A 2017 study on deciduous fourth premolars—deciduous teeth are less affected by environmental factors as they soon fall out and are replaced by permanent teeth—found that Nakalipithecus and future African apes (including australopithecines) shared more similarities with each other than to Eurasian apes, though drew no clear conclusion on the Nakalipithecus–Ouranopithecus relationship.[3]
Nakalipithecus has also been proposed to have been the ancestor to the 8 million year old Chororapithecus, which possibly represents an early member of the gorilla line; if both of these are correct, then Nakalipithecus could potentially represent an early gorilla.[2]
Anatomy
Nakalipithecus has an overall large size, with teeth similar in size to those of female gorillas and orangutans. The specimen is thus presumed female. Samburupithecus was about the same size. Unlike other apes, the canines are short, as long as they are wide. The premolars are elongated, and the protoconid (the cusp on the tongue side) of the third premolar is oriented more cheekwards, which is a distinguishing characteristic of Miocene African apes from Miocene Eurasian apes. Compared to contemporary African apes, the tooth enamel on the molars is thinner, and the cusps (which project outward from the tooth) are less inflated, creating a wider basin. Like modern and some contemporary apes, but unlike earlier East African apes, the first molar is relatively large, with an M1/M2 ratio of about 85%. Like Ouranopithecus and early Indian Sivapithecus, but unlike most contemporary and future apes, the third molar was much larger than the second, with an M3/M2 ratio of 115%, though this ratio is smaller than that of the Southeast Asian Khoratpithecus. The mandible is less robust than those of Eurasian Miocene apes, except for Ouranopithecus.[1]
Palaeobiology
The Late Miocene of East Africa, the Sahara, the Middle East, and Southern Europe all appear to have been predominantly a seasonal sclerophyllous evergreen woodland environment. Nakali appears to have been dominated by C3 (forest) plants. Nakalipithecus is known from the Upper Beds, which comprise lakeside or riverine deposits.[1] Climate change caused the expansion of grasslands in Africa from 10–7 milling years ago, likely fragmenting populations of forest-dwelling primates.[4]
Nakali has also yielded a black rhino specimen,[5] the pig Nyanzachoerus, an antelope, the hippo Kenyapotamus, the rhino Kenyatherium, the giraffe Palaeotragus,[6] the horse Hipparion,[7] the elephant Deinotherium and possibly Choerolophodon,[6] and the colobine monkey Microcolobus.[8] The third premolar of a small nyanzapithecine ape was also found in Nakali,[9][4] and Samburupithecus was nearly contemporaneous with Nakalipithecus, and was discovered 60 km (37 mi) to the north of Nakali.[1]
See also
References
- ^ a b c d e f Kunimatsu, Y.; Nakatsukasa, M.; Sawada, Y.; Sakai, T. (2007). "A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans". Proceedings of the National Academy of Sciences. 104 (49): 19220–19225. doi:10.1073/pnas.0706190104. PMC 2148271. PMID 18024593.
- ^ a b Katoh, S.; Beyene, Y.; Itaya, T.; et al. (2016). "New geological and palaeontological age constraint for the gorilla–human lineage split". Nature. 530: 215–218. doi:10.1038/nature16510.
- ^ Morita, W.; Morimoto, N.; Kunimatsu, Y.; et al. (2017). "A morphometric mapping analysis of lower fourth deciduous premolar in hominoids: Implications for phylogenetic relationship between Nakalipithecus and Ouranopithecus". Comptes Rendus Palevol. 116 (5–6): 655–669. doi:10.1016/j.crpv.2016.10.004.
- ^ a b Kunimatsu, Y.; Sawada, Y.; Sakai, T.; et al. (2017). "The latest occurrence of the nyanzapithecines from the early Late Miocene Nakali Formation in Kenya, East Africa". Anthropological Science. 125 (2): 45–51. doi:10.1537/ase.170126.
- ^ Handa, N.; Nakatsukasa., M.; Kunimatsu, Y.; Nakaya, H. (2019). "Additional specimens of Diceros (Perissodactyla, Rhinocerotidae) from the Upper Miocene Nakali Formation in Nakali, central Kenya". Historical Biology. 31 (2): 262–273. doi:10.1080/08912963.2017.1362560.
- ^ a b Benefit, B. R.; Pickford, M. (1986). "Miocene fossil cercopithecoids from Kenya". Physical Journal of Anthropology. 69 (4): 441–464. doi:10.1002/ajpa.1330690404.
- ^ Nakaya, H.; Uno, K.; Fukuchi, A.; et al. (2010). "Late Miocene paleoenvironment of hominoids—mesowear analysis of fossil ungulate cheek teeth from northern Kenya". International Primatological Society. 26: 147. doi:10.14907/primate.26.0.147.0.
- ^ Nakatsukasa, M.; Mbua, E.; Sawada, Y.; et al. (2010). "Earliest colobine skeletons from Nakali, Kenya". Physical Journal of Anthropology. 143 (3): 365–382. doi:10.1002/ajpa.21327.
- ^ Kunimatsu, Y.; Nakatsukasa, M.; Sawada, Y. (2016). "A second hominoid species in the early Late Miocene fauna of Nakali (Kenya)". Anthropological Science. 124 (2): 75–83. doi:10.1537/ase.160331.
External links
- Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016).
- "Mama, Is That You? Possible Ape Ancestor Found". Discovery News. Version of 2007-NOV-12. Retrieved 2007-NOV-13. Contains photo of fossil.
