Kantis: A new Australopithecus site on the shoulders of the Rift Valley near Nairobi, Kenya

Abstract

Most Plio-Pleistocene sites in the Gregory Rift Valley that have yielded abundant fossil hominins lie on the Rift Valley floor. Here we report a new Pliocene site, Kantis, on the shoulder of the Gregory Rift Valley, which extends the geographical range of Australopithecus afarensis to the highlands of Kenya. This species, known from sites in Ethiopia, Tanzania, and possibly Kenya, is believed to be adapted to a wide spectrum of habitats, from open grassland to woodland. The Kantis fauna is generally similar to that reported from other contemporaneous A. afarensis sites on the Rift Valley floor. However, its faunal composition and stable carbon isotopic data from dental enamel suggest a stronger C4 environment than that present at those sites. Although the Gregory Rift Valley has been the focus of paleontologists' attention for many years, surveys of the Rift shoulder may provide new perspective on African Pliocene mammal and hominin evolution.

Dentognathic remains of Australopithecus afarensis from Nefuraytu (Woranso-Mille, Ethiopia): Comparative description, geology, and paleoecological context

“…Australopithecus afarensis is one of the best known hominin species in the Pliocene fossil record and hypothesized as the direct descendant of the 4.2-3.9 Ma Australopithecus anamensis (Leakey et al, 1995(Leakey et al, , 1998Ward et al, 2001;White et al, 2006). Its remains have been recovered from sites in Ethiopia, Kenya, and Tanzania from deposits ranging in age from 3.7-2.9 million years ago (Ma) (Johanson and Taieb, 1976;Taieb et al, 1976;Johanson et al, 1978aJohanson et al, ,b, 1982aKimbel and White, 1988;Kimbel et al, 1985Kimbel et al, , 1994Kimbel et al, , 2004White et al, 1993White et al, , 2000Brown et al, 2001;Kimbel and Delezene, 2009;Harrison, 2011;Mbua et al, 2016). The best sample of the species comes from Hadar, in the Afar region of Ethiopia, where hundreds of specimens representing males and females of juvenile and adult individuals have been recovered since the early 1970s (Johanson and Taieb, 1976;Johanson et al, 1978aJohanson et al, ,b, 1982aKimbel et al, 1994Kimbel et al, , 2004.…”

Climate-inferred distribution estimates of mid-to-late Pliocene hominins

“…Kantis, Kenya Mbua et al, (2016) indicate a mosaic of woodland, shrubland, grassland with more C4 than other Au. afarensis sites.…”

New Pliocene hominin remains from the Leado Dido’a area of Woranso-Mille, Ethiopia

“…Characterization of premolar root configuration follows Moore et al (2016). Metrics for the comparative fossil sample were compiled from the literature (White, 1977(White, , 1980Suwa, 1990;Suwa et al, 1994;Brunet et al, 1995Brunet et al, , 1996Leakey et al, 1995Leakey et al, , 2001Ward et al, 1999Ward et al, , 2001Ward et al, , 2013Ward et al, , 2020White et al, 2000White et al, , 2006Brown et al, 2001;Kimbel et al, 2004;Alemseged et al, 2005;Moggi-Cecchi et al, 2006;Spoor et al, 2010;Delezene and Kimbel, 2011;Harrison, 2011;Manthi et al, 2012;, 2016aMbua et al, 2016;Skinner et al, 2020) and checked for interobserver comparability in the course of the authors' first-hand study of the original specimens. For most morphological features, the LDD sample is too small to merit formal statistical tests.…”

“…Australopithecus afarensis specimens with similar C 1 shape indices include L.H. 6 2 and KNM-RK 53800 (Mbua et al, 2016).…”

“…6. Another specimen exhibiting a fair degree of MD elongation in combination with derived qualitative features is the upper canine from Kantis, Kenya, KNM-RK 53800 (shape index ¼ 0.99; Mbua et al, 2016). Like LDD-VP-1/248, KNM-RK 53800 is dated to chron C2An.3n (3.59e3.33 Ma).…”