Ecological and temporal placement of early Pliocene hominids at Aramis, Ethiopia

Abstract

Sedimentary deposits in the Middle Awash research area of Ethiopia's Afar depression have yielded vertebrate fossils including the most ancient hominids known. Radioisotopic dating, geochemical analysis of interbedded volcanic ashes and biochronological considerations place the hominid-bearing deposits at around 4.4 million years of age. Sedimentological, botanical and faunal evidence suggests a wooded habitat for the Aramis hominids.

Taphonomic analysis of skeletal remains from chimpanzee hunts at Ngogo, Kibale National Park, Uganda

“…Finally, pre-technological hominins were similar in body size to modem chimpanzees (McHenry, 1992), lived in more closed environments than later hominins (WoldeGabriel et al, 1994;Pickford and Senut, 2001;WoldeGabriel et al, 2001;Vignaud, et al, 2002), and may have retained some tree-climbing adaptations (Richmond, 1998;Hailie-Selassie, 2001;Senut et al, 2001;Ward, 2002). We suggest that if pre-stone toolusing Pliocene hominins hunted and consumed small sized prey, the taphonomic signature of that hunting behavior would be more similar to chimpanzee consumption of small prey than Oldowan hominin stone tool-assisted butchery of larger prey.…”

“…Ardipithecus ramidus kadabha specimens from the Central Awash Complex (at 5.54•5.77 Ma) were deposited in a wooded and possibly humid environment (WoldeGabriel et al, 2001). The fauna associated with Ardipithecus ramidus from Aramis, Ethiopia (at 4.4 Ma) is dominated by colobine monkeys (over 30% of all identifiable vertebrates in the assemblage) in a closed, wooded environment (WoldeGabriel et al, 1994). Australopithecus anamensis specimens from Asa Issie (at 4.1•4.2 Ma) were also deposited in a wooded environment, and the fauna is heavily dominated by cercopithecid primates (just under 50% of all identifiable macrovertebrates; White et al, 2006).…”

The Red Sea, Coastal Landscapes, and Hominin Dispersals

“…The Afar region in the southwest corner of the broader region under discussion here offers one of the longest sequences and some of the earliest hominin fossils in Africa, including finds of Australopithecus afarensis and Ardipithecus ramidus, and earliest fossil remains of modern humans (Johansen and Taieb, 1976;Woldegabriel et al, 1994;White et al, 2003). Whether this reflects unusually favorable geological conditions for exposing early deposits compared to other regions or a genuine focus of early hominin evolution and settlement remains unclear.…”

New Eucyon remains from the Pliocene Aramis Member (Sagantole Formation), Middle Awash Valley (Ethiopia)

“…Wolde Gabriel et a!. [12] reported 40 Ar;39 Ar resnlts and uniform chemical data on glass from different ontcrops of the DABT. The DABT occurs in close association with the GATC along the eastern half of the Central Awash Com plex.…”