Australopithecus bahrelghazali

Australopithecus bahrelghazali
Fossil
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Subfamily: Homininae
Genus: Australopithecus or Praeanthropus
Species: A. bahrelghazali or P. bahrelghazali
Binomial name
†Australopithecus bahrelghazali
Brunet et al., 1995

Australopithecus bahrelghazali is a fossil hominin discovered in 1995 by a Franco-Chadian team led by the paleontologist Michel Brunet. Two fossils have been described:

- A mandibular fragment found at Chad east of the Bahr el Ghazal ("river of gazelles") to about forty-five kilometers from the fort of Koro Toro, by the Franco-Chadian team of Michel Brunet (paleontologist) January 23, 1995 on the site called KT12. Named after the name of the fossil valley near where it was discovered, cataloged KT12 / H1, the holotype consists of a mandibular fragment, a lower second incisor, both lower canines, and all four of its premolars, still affixed within the dental alveoli.

- An upper premolar of another individual find on the same place january 1996. This paratype is cataloged KT12 / H2.[1][2][3][4]

A third fossil, a fragment of maxilla left, was collected January 16, 1996 on the site of KT13, KT12 close neighbor. Cataloged KT13-96-H1, it appears in a scientific article in 1997 as Australopithecus sp. Indet. before to be named Australopithecus bahrelghazali in 2012.[5][6][7]

Finally, a fourth fossil mandibular fragment with two teeth was unearthed July 18, 2000 a few kilometers south of the site KT13 on the new site of KT40. The three sites hominids KT12, KT13 and KT40 are located at the foot of the same sandy cord, the Goz Kerki, testimony of a former shoreline MégaTchad. The fossil potential of this sector therefore remains important.[8]

Australopithecus bahrelghazali was dated by beryllium-based radiometric dating as living about 3.6 million years ago.[9]

The specimen locality is roughly 2,500 kilometers west of the East African Great Rift Valley, making it far removed from what broadly thought to be the "cradle" area of human evolution. (The specimen's proper name is KT-12/H1; Brunet named it Abel as a dedication to his deceased colleague Abel Brillanceau.)

The KT-12/H1 mandible has similar features to the dentition of Australopithecus afarensis, which fact has caused researcher William Kimbel to argue that Abel is not a separate species, but "falls within the range of variation" of the species Australopithecus afarensis. By 1996, Brunet and his team classified KT-12/H1 as the holotype specimen for Australopithecus bahrelghazali.[5]This claim is difficult to substantiate, as the describers, contrary to the International Code of Zoological Nomenclature, have kept the specimen locked away from inspection by the general paleoanthropological community.[10] A. bahrelghazali is unique as it is the only australopithecine fossil found in Central Africa. It is also of great importance as it is the first fossil to show that there is a geographical "third window", that is, beyond East Africa and South Africa, of early hominin evolution.[11][12]

Timelines

See also

References

  1. ↑ Michel Brunet, Beauvilain, A., Yves Coppens, Heintz, É., Moutaye, A.H.E et Pilbeam, D. David Pilbeam (1995) - The first australopithecine 2,500 kilometres west of the Rift Valley (Chad). Nature (journal), 378, pp. 273-275.
  2. ↑ Brunet M., Beauvilain, A., Yves Coppens, Heintz, É., Moutaye, A.H.E et Pilbeam, D. (1996) - Australopithecus bahrelghazali, une nouvelle espèce d'Hominidé ancien de la région de Koro Toro (Tchad). Comptes rendus des séances de l'Académie des Sciences, vol. 322, pp. 907-913.
  3. ↑ Australopithecus bahrelghazali, 'Abel'.
  4. ↑ Eugene M., McCarthy (n.d.). "Australopithecus bahrelghazali". Macroevolution.net. Retrieved 8 January 2015. Etymology: Since the type specimen of Australopithecus bahrelghazali was found near the Bahr el Ghazal river valley, its name was created by adding the Latin genitive ending -i to bahrelghazal, yielding bahrelghazali, meaning 'of the Bahr el Ghazal'.
  5. 1 2 Tchad, un nouveau site à Hominidés Pliocène. Comptes rendus des séances de l'Académie des Sciences, t. 324, série IIa, p. 341 à 345.
  6. ↑ Lee-Thorp J., Likius A., Mackaye H.T., Vignaud P., Sponheimer M. et Brunet M. Isotopic evidence for an early shift to C4 resources by Pliocene hominins in Chad et dans 'Supporting information' de cet article.
  7. ↑ The jawbone of the Australopithecus bahrelghazali of KT13.
  8. ↑ Mandibular symphysis of the Hominid of KT40.
  9. ↑ Anne-Elisabeth Lebatard, Didier L. Bourlès, Philippe Duringer, Marc Jolivet, Régis Braucher, Julien Carcaillet, Mathieu Schuster, Nicolas Arnaud, Patrick Monié, Fabrice Lihoreau, Andossa Likius, Hassan Taisso Mackaye, Patrick Vignaud, and Michel Brunet (2008) Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad. Proc. Natl. Acad. Sci. U.S.A., 105(9): 3226-3231.
  10. ↑ Schwartz, Jeffrey H., and Ian Tattersal. 2005 The Human Fossil Record, vol.4: Craniodental Morphology of Early Hominids (Genera Australopithecus, Paranthropus, Orrorin) and Overview. John Wiley and Sons, New Jersey.
  11. ↑ Ann Gibbons (2007). The First Human. Doubleday Publishing Group. p. 8. ISBN 0307279820. Retrieved 2015-03-18.
  12. ↑ John Reader (2011). Missing links : in search of human origins. p. 393. Oxford University Press, New York, ISBN 978-0-19-927685-1.

External links

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