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Whole communities of ape-like creatures may have been killed in volcanic disasters that struck East Africa 18 million years ago... the once active volcano Kisingiri... contained fossils of what is believed to be a forerunner of humans called Proconsul... they may have been caught by a pyroclastic flow... the abundance of the hominoid fossils may represent "death assemblages" -- whole populations wiped out simultaneously by "glowing cloud" eruptions. [Monday, May 3, 1999, "Early volcano victims discovered"]
New chronology for the
Early Miocene mammalian faunas
of Kisingiri, Western Kenya
R. E. Drake, J. A. Van Couvering,
M. H. Pickford, G. H. Curtis
& J. A. Harris
Journal of the Geological Society; 1988; v. 145; issue.3; p. 479-491
New total-fusion K-Ar ages indicate that all of the fossiliferous formations that make up the lower part of the Early Miocene Kisingiri sequence in western Kenya at Rusinga Island, Mfwangano Island, and Karungu were deposited during an interval of less than 0.5 million years at c. 17.8 Ma ago. This contrasts markedly with K-Ar ages previously published from these detrital-tuffaceous formations, which suggested that they were deposited over an interval of as much as 7 million years between 23 and 16 Ma, overlapping the age-ranges of all other East African Early Miocene sites including Koru, Songhor, Napak, Bukwa, Loperot, Muruarot and Buluk. In addition, the analytical problems revealed by the new Kisingiri results cast doubt on biotite ages which provide dating for the most important sites. Thus, the strong differences between the Kisingiri fauna and those of Koru, Sonhor and Napak, long held to be due to ecology because of the apparent overlap in ages, may actually be due to a difference in time. If this view of the geochronology is correct, it may now be possible to identify adaptive trends and evolutionary succession in the East African Early Miocene faunas.

The Ape in the Tree:
An Intellectual and Natural History of Proconsul
by Alan Walker and Pat Shipman

other hc edition