User:Stephdc/Aramis, Ethiopia

Aramis, Ethiopa

Geography

The Middle Awash study area covers 5,000 km2, with recent alluvium and/or volcanics covering more than 80% of that area. The current Awash River travels south to north across the study region, eventually emptying into Lake Abbé on the Ethiopia-Djibouti border. The Awash River is fed by perennial and seasonal tributaries that originate in the highlands along the western shoulder and escarpment. The elevation of the Middle Awash study area varies from around 550 meters along the Awash River to around 850 meters near the western margin's foothills.

Ecological and temporal placement of early Pilocene hominids in Aramis, Ethiopa

The Middle Awash research region is located south of Hadar and crosses the present Awash River. The area's palaeoanthropological significance was identified by Taieb in the 1960s, after geological work began in 1938. Between 1975 and 1978, the RVRME (Rift Valley Research Mission in Ethiopia) conducted additional research, followed by their team in 1981. Sedimentary layers in Ethiopia's Afar depression's Middle Awash research area have revealed vertebrate fossils, including the world's oldest hominids. The hominid-bearing layers are 4.4 million years old, according to radioisotopic dating, geochemical examination of interbedded volcanic ashes, and biochronological factors. Sedimentological, botanical, and faunal evidence point to the Aramis hominid inhabiting a forest environment. The first deposits discovered are found around the western edge of Afar. These are late Miocene biochronologically. They haven't revealed any hominid skeletons. Pliocene sediments, which crop out east and west of the present river, are the thickest and most widely exposed Middle Awash deposits. The investigation concentrated on the region exposed between the upper Adgantoli and lower Sagantole drainages after Gen Suwa discovered hominid fossils in the Aramis headwaters on December 17, 1992. Older sediments were gradually uplifted above the Awash valley floor and are now exposed on the center complex's flanks. The 'Aramis' and 'Haradaso' Members of the RVRME were biochronologically identified between 3.5 and 4.5 Myr. The species A. afarensis, which is presumed to be descended from the Aramis hominids, is thought to have exhibited a wide range of ecological tolerances, as evidenced by the fact that its bones have been discovered in rather open settings. It's probable that early Aramis hominids avoided these rather open areas, which would have predated A. afarensis's spread out of woodland habitats. This could explain why there are so few basal Pliocene hominid remains in non-woodland locations in the Middle Awash and elsewhere.

Late Miocene Hominids

Late Miocene Homininds

New hominid remains from Ethiopia's Middle Awash region that age from 5.2–5.8 Myr and are linked to a forested paleoenvironment have been discovered. These Late Miocene fossils belong to the hominid genus Ardipithecus and are the first definitive proof of the clade's existence. All younger hominids share derived dental features solely. This suggests that the fossils belong to a hominid taxon that existed before the split in lineages that led to contemporary chimps and humans. Ardipithecus was phylogenetically near to the common ancestor of chimps and humans, based on the survival of primitive dental and postcranial features in these new fossils. Environmental signs point to a forested environment. Since the first (a partial mandible) was discovered in Alayla in 1997, 11 hominid specimens have been discovered at five different locations.

References

1. WoldeGabriel. Ecological and temporal placement of early Pliocene hominids at Aramis, Ethiopia. 1994;371(6495). doi:10.1038/371330a0

2. Haile-Selassie, Y. Late Miocene hominids from the Middle Awash, Ethiopia. Nature 412, 178–181 (2001). https://doi.org/10.1038/35084063

3. Haile-Selassie, Y. (n.d.). Mio-Pliocene mammals from the Middle Awash, Ethiopia.