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Chirchir H, Kivell TL, Ruff CB, Hublin JJ, Carlson KJ, Zipfel B, Richmond BG.Chirchir H, et al. Among authors: kivell tl.Proc Natl Acad Sci U S A. 2015 Jan 13;112(2):366-71. doi: 10.1073/pnas.1411696112. Epub 2014 Dec 22.Proc Natl Acad Sci U S A. 2015.PMID: 25535354Free PMC article.