Ledi-Geraru is a paleoanthropological research area in Mille district,

Afar Region The Afar Region (; aa, Qafar Rakaakayak; am, አፋር ክልል), formerly known as Region 2, is a regional state in northeastern Ethiopia and the homeland of the Afar people. Its capital is the planned city of Semera, which lies on the paved ...

, northeastern

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

, along the Ledi and Geraru rivers (two left tributaries of the Awash, south of the

Mille river The Mille River is a river of Ethiopia and a tributary of the Awash. It drains parts of the Semien (North) Wollo and Debub (South) Wollo Zones of the Amhara Region, as well as Administrative Zone 4 of the Afar Region. The explorer L.M. Nesbitt ...

). It stretches for about 50 km, located just to the northeast of the Hadar paleoanthropological area. Early research was conducted in 1972–1974 The Ledi-Geraru Research Project was launched in 2002. The site is known for its early stone tools, dated about 2.6 million years old. A hominin mandible was found in 2013, known as

LD 350-1 LD 350-1 is the earliest known specimen of the genus ''Homo'', dating to 2.8–2.75 million years ago (mya), found in the Ledi-Geraru site in the Afar Region of Ethiopia. The specimen was discovered in silts above the Gurumaha Tuff section of the ...

and dated 2.8 million years old, which may qualify as a very early specimen of the genus ''Homo''.

LD 350-1

LD 350-1 is a fossil

hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The t ...

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

fragment discovered in 2013 at the Ledi-Geraru site. It was found by Chalachew Seyoum, an Ethiopian graduate student in the

Institute of Human Origins The Institute of Human Origins (IHO) is a non-profit, multidisciplinary research organization dedicated to the recovery and analysis of the fossil evidence for human evolution. It was founded by the team of paleoanthropologists that discovered Lucy ...

Arizona State University Arizona State University (Arizona State or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...

. The fossil was stratigraphically dated to 2.80 to 2.75 million years old.Villmoare et al. (2015): "The Gurumaha Tuff is radiometrically dated to , a date that is consistent with the normal magnetic polarity of the Gurumaha section, presumably the Gauss Chron. An upper bounding age for LD 350-1 is provided by an adjacent, downfaulted younger block that contains the Lee Adoyta Tuff. ..the age of LD 350-1 can be further constrained by stratigraphic scaling. ..Based on the current chronostratigraphic framework for Ledi-Geraru, we consider the age of LD 350-1 to be 2.80-2.75 Ma". See also: It has been described as combining "primitive traits seen in early ''

Australopithecus ''Australopithecus'' (, ; ) is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genus ''Homo'' (which includes modern humans) emerged within ''Australopithecus'', as sister to e.g. ''Australopi ...

'' with derived morphology observed in later ''

Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus ''Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relate ...

''. . See also: . The fossil is the left mandibular body, but does not include the ascending ramus. It has attached the three

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

, both

premolars The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

, and the left canine, some of which have complete crowns.

References

* {{cite journal , last1 = Dimaggio , first1 = E. N. , display-authors = etal , year = 2015, title = Tephrostratigraphy and depositional environment of young (<2.94 Ma) Hadar Formation deposits at Ledi-Geraru, Afar, Ethiopia , journal = Journal of African Earth Sciences , volume = 112, pages = 234–250, doi = 10.1016/j.jafrearsci.2015.09.018 , doi-access = free Afar Region Archaeological sites in Ethiopia Archaeological sites of Eastern Africa