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]
