OMO KIBISH
LOCATION
Sites KHS (Om0 I) and PHS (Orno 11) in sediments
of the Kibish Fm, Lower Orno Basin, southern
Ethiopia. Both sites lie to the N of Shiangoro village
(see map in Butzer, 1969), the first on the E, the
second on the W bank of the Orno River. Orno I11 is
geographically unlocalized within the Kibish Fm.
DISCOVERY
Kenyan contingent of the Paleontological Research
Expedition to the Orno Valley, led by R. Leakey, 1967.
MATERIAL
Partial skeleton including highly fragmentary skull
(Om0 I); calvaria with much of cranial base (Om0 11);
glabellar and frontoparietal fragments (Om0 111).
All8 adult.
DATING AND STRATIGRAPHIC CONTEXT
Orno I was found, partly in situ, in a “minor discon-
formity” within the upper one-third of Member 1 of
the Kibish Fm; Orno I1 was a surface find some 3 km
distant but apparently at the same stratigraphic level
(Butzer, 1969), or possibly closer to the base of Mem-
ber 1 (Day and Stringer, 1991). The exact site of
recovery of Orno 111 seems to have gone unrecorded,
but was somehow “related” to Member 3 of the Kibish
Fm (R. Leakey, quoted in Butzer, 1969). Butzer
(1976) reported that the Kibish Fm spanned the
period between about 130 and 3 Ka, with the
Member 1 hominids at the early end of this range
based on a single U/Th date on mollusk shells. The
later Member 3 beds in which Orno 111 was found
yielded a minimum radiocarbon date of around 37 Ka
(Butzer, 1976). The fauna associated with Orno I is
said to indicate the end of the Middle Pleistocene or
the beginning of the Upper Pleistocene (Day and
Stringer, 1991); this sits fairly comfortably with the
130 Ka U/Th date, but there is still a fair measure of
uncertainty as to the exact age of the specimen (e.g.,
Howell, 1978). Yet more uncertainty must attach to
the Orno I1 specimen since it was a surface find, but
the likelihood is that it is as old as, if not slightly older
than, Orno I.ARCHAEOLOGICAL CONTEXT
A few unremarkable flakes found in association with
Orno I have been attributed to the Middle Stone Age
(Klein, 1983). Orno I1 and 111 lack any archaeological
context at all.PREVIOUS DESCRIPTIONS AND ANALYSES
The Orno Kibish hominids were initially described
by Day (1969), who found that all fell within the
range of variation of Homo sapiens. However, he noted
that the two crania were strikingly different from each
other, Orno I being more modern in shape, while
Orno I1 recalled more “archaic” forms. The fairly
uninformative Orno 111 fragments more closely re-
sembled Orno I. Rightmire (e.g., 1981) and Brauer
(1984) have supported the notion that a single kind of235