Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia

McDougall, Ian, Brown, Francis H. and Fleagle, John G. (2008) Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia. Journal of Human Evolution, 55 3: 409-420. doi:10.1016/j.jhevol.2008.05.012

Author McDougall, Ian
Brown, Francis H.
Fleagle, John G.
Title Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia
Journal name Journal of Human Evolution   Check publisher's open access policy
ISSN 0047-2484
Publication date 2008-09
Sub-type Article (original research)
DOI 10.1016/j.jhevol.2008.05.012
Volume 55
Issue 3
Start page 409
End page 420
Total pages 12
Editor David Begun
Steven R. Leigh
Susan C. Anton
Place of publication Kent, United Kingdom
Publisher Academic Press
Language eng
Subject 0604 Genetics
1601 Anthropology
Formatted abstract
The provenance and age of two Homo sapiens fossils (Omo I and Omo II) from the Kibish Formation in southern Ethiopia have been much debated. Here we confirm that Omo I and the somewhat more primitive-looking Omo II calvariae are from similar stratigraphic levels in Member I of the Kibish Formation. Based on 40Ar/39Ar age measurements on alkali feldspar crystals from pumice clasts in the Nakaa'kire Tuff, a tuffaceous bed in Member I just below the hominin levels, we place an older limit of 198 ± 14 ka (weighted mean age = 196 ± 2 ka) for the hominins. A younger limit of 104 ± 7 ka (weighted mean age = 104 ± 1 ka) is provided by feldspars separated from pumice clasts in the Aliyo Tuff in Member III. Geological evidence indicates rapid deposition of each member of the Kibish Formation, concurrent with deposition of sapropels in the Mediterranean Sea. The 40Ar/39Ar age measurements, together with correlations with sapropels, indicate that the hominin fossils are close in age to the older limit. Our preferred estimate of the age of the hominins is 195 ± 5 ka, making them the earliest well-dated anatomically modern humans yet described.

Keyword 40Ar/39Ar dating
Kibish Formation
Modern hominins
Mediterranean sapropels
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Earth Sciences Publications
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