Allia Bay

The Allia Bay is a region on the east side of Lake Turkana[1] in Kenya. The site is known for yielding its first hominid fossils in 1982 with further findings to this day, all of which have been identified as part of Australopithecus anamensis but possibly related to Australopithecus afarensis. Notable people with findings at Allia Bay include Richard Leakey, Meave Leakey, Craig Feibel, Ian McDougall, Alan Walker.[2]

Geography

The geographic coordinates of Allia Bay are 3°35′4″N, 36°16′4″E. As a set of isolate exposures it forms the southernmost region of Koobi Fora.[3] One of its distinct features is the c.4.2 Ma "bone bed",[3] which was likely a channel of the ancestral Omo River.[3]

Findings

All of the specimens were found to be 3.9 to 4.4 million years old[2] and were dated using 3 main methods: argon-argon dating, potassium-argon dating, and magnetostratigraphy.[3] Leakey, Feibel, McDougall, and Walker were involved in the discovery of 12 new specimens, presumed to be a new species within the genus Australopithecus.[2] The new species was thought to be a possible ancestor of Australopithecus afarensis and a sister species of Ardipithecus ramidus.[3] The 12 specimens found at Allia Bay were in conjunction with an additional nine that were found at Kanapoi in Kenya; these two sites' findings are the basis of a new, singular species within Australopithecus, for which the first Kanapoi specimen is the holotype, and the later Kanapoi and Allia Bay findings are paratypes.[4] The Allia Bay specimens, listed in the table below, were found in or under the Moiti Tuff and have a mean age of 3.89 million years[3]

Specimen Number Date Site Body Part Discoverer
KMN-ER 7727 1982 Allia Bay 261-1 Left M2 J. Kithumbi
KMN-ER 20419 1988 Allia Bay 251 Left radius M. Kyeva
KMN-ER 20420 1988 Allia Bay 261-1 Left M2 J. Kimengich
KMN-ER 20421 1988 Allia Bay 261-1 Right M3 Sieving team
KMN-ER 20422 1988 Allia Bay 261-1 Left M1 Sieving team
KMN-ER 20423 1988 Allia Bay 261-1 Left M2 Sieving team
KMN-ER 20427 1988 Allia Bay 261-1 Left M1 Sieving team
KMN-ER 20428 1988 Allia Bay 261-1 Left M3 Sieving team
KMN-ER 20432 1988 Allia Bay 261-1 Left mandible fragment with canine root and P3-4 Sieving team
KMN-ER 22683 1988 Allia Bay 261-1 Left P4 Sieving team
KMN-ER 24148 1988 Allia Bay 261-1 Left dm2 Sieving team
KMN-ER 30203 1995 Allia Bay 261-1 Right I1 A. Walker
KMN-ER 30200 1995 Allia Bay 261 Left maxilla with M1 3 K. Kimeu

The method by which these specimens were named is concurrent with those found at Kanapoi: KNM-ER stands for Kenya National Museum - East Rudolf, where Rudolf is the lesser known, alternative name for Lake Turkana.[3]

References
  1. Schoeninger, Margaret J.; Reeser, Holly; Hallin, Kris (2003). "Paleoenvironment of Austrolopithecus anamensis at Allia Bay, East Turkana, Kenya: evidence from mammalian herbivore enamel stable isotopes" (PDF). Journal of Anthropological Archaeology – via Academic Press.
  2. Leakey, Meave G.; Feibel, Craig S.; McDougall, Ian; Walker, Alan (August 17, 1995). "New four-million-year-old hominid species from kanapoi and allia bay, kenya". Nature. 376 (6541): 565. Bibcode:1995Natur.376..565L. doi:10.1038/376565a0. PMID 7637803.
  3. Wood, Bernard, ed. (2013). Wiley-Blackwell Encyclopedia of Human Evolution. Wiley-Blackwell. pp. 18–19. ISBN 978-1-118-65099-8.
  4. Ward, C.V.; Leakey, M.G.; Walker, A. (2001-10-01). "Morphology of Australopithecus anamensis from Kanapoi and Allia Bay, Kenya". Journal of Human Evolution. 41 (4): 255–368. doi:10.1006/jhev.2001.0507. ISSN 0047-2484. PMID 11599925.
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