''Australopithecus deyiremeda'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

australopithecine Australopithecina or Hominina is a subtribe in the tribe Hominini. The members of the subtribe are generally ''Australopithecus'' (cladistically including the genus, genera ''Homo'', ''Paranthropus'', and ''Kenyanthropus''), and it typically in ...

from Woranso–Mille, Afar Region, Ethiopia, about 3.5 to 3.3 million years ago during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58A. afarensis ''Australopithecus afarensis'' is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa. The first fossils were discovered in the 1930s, but major fossil finds would not ta ...

''. ''A. deyiremeda'' is distinguished by its forward-facing cheek bones and small

cheek teeth Cheek teeth or post-canines comprise the molar and premolar teeth in mammals. Cheek teeth are multicuspidate (having many folds or tubercles). Mammals have multicuspidate molars (three in placentals, four in marsupials, in each jaw quadrant) and ...

compared to those of other early

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 ...

s. It is unclear if a partial foot specimen exhibiting a dextrous big toe (a characteristic unknown in any australopith) can be assigned to ''A. deyiremeda''. ''A. deyiremeda'' lived in a mosaic environment featuring both open grasslands and lake- or riverside forests, and anthropologist Fred Spoor suggests it may have been involved in the Kenyan

Lomekwi Lomekwi 3 is the name of an archaeological site in Kenya where ancient stone tools have been discovered dating to 3.3 million years ago, which make them the oldest ever found. Discovery In July 2011, a team of archeologists led by Sonia Harman ...

stone-tool industry typically assigned to ''

Kenyanthropus ''Kenyanthropus'' is a hominin genus identified from the Lomekwi site by Lake Turkana, Kenya, dated to 3.3 to 3.2 million years ago during the Middle Pliocene. It contains one species, ''K. platyops'', but may also include the 2 million year ol ...

''. ''A. deyiremeda'' coexisted with ''A. afarensis'', and they may have exhibited niche partitioning to avoid

competing Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

with each other for the same resources, such as by relying on different fallback foods during leaner times.

Taxonomy

''Australopithecus deyiremeda'' was first proposed in 2015 by Ethiopian palaeoanthropologist Yohannes Haile-Selassie and colleagues based on jawbone fossils from the Burtele and Waytaleyta areas of Woranso–Mille, Afar Region, Ethiopia. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen, a young adult left

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

with all teeth except the first incisor and third molar BRT-VP-3/1, was discovered on 4 March 2011 by local resident Mohammed Barao. The paratype specimens are a complete adult

body of the 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 teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

with all incisors BRT-VP-3/14, and an adult right toothless jawbone WYT-VP-2/10, which were discovered by Ethiopian fossil hunter Ato Alemayehu Asfaw . A right maxilla fragment with the fourth

premolar 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 ...

BRT-VP-3/37 was found east of BRT-VP-3/14, and it is unclear if these belonged to the same individual. The sediments were

radiometrically dated Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

to 3.5–3.3 million years ago, the

Middle Pliocene Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ( ...

. The describers believed the remains were distinct enough from the contemporary and well-known ''

A. afarensis ''Australopithecus afarensis'' is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa. The first fossils were discovered in the 1930s, but major fossil finds would not ta ...

'' to warrant species distinction, and ''A. deyiremeda'' is counted among a growing diversity of

Late Pliocene Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

s alongside ''A. afarensis'', ''

A. bahrelghazali ''Australopithecus bahrelghazali'' is an extinct species of australopithecine discovered in 1995 at Koro Toro, Bahr el Gazel, Chad, existing around 3.5 million years ago in the Pliocene. It is the first and only australopithecine known from Ce ...

'' and '' Kenyanthropus platyops''. The name ''deyiremeda'' derives from the

Afar language The Afar language ( aa, Qafaraf, links=no; also known as ’Afar Af, Afaraf, Qafar af) is an Afroasiatic language belonging to the Cushitic branch. It is spoken by the Afar people inhabiting Djibouti, Eritrea and Ethiopia. Classification Afar ...

meaning "close relative" because, existing so early in time, the discoverers considered ''A. deyiremeda'' to have been closely related to future australopiths. However, though the proposed distinguishing characteristics are apparently

statistically significant In statistical hypothesis testing, a result has statistical significance when it is very unlikely to have occurred given the null hypothesis (simply by chance alone). More precisely, a study's defined significance level, denoted by \alpha, is the p ...

, given how few specimens of ''A. deyiremeda'' exist, it is unclear if this indeed warrants species distinction or if these specimens simply add to the normal range of variation for ''A. afarensis''. If it is a valid species, then it could possibly indicate some ''A. afarensis'' specimens are currently classified into the wrong species. Haile-Selassie and colleagues noted that, though it shares many similarities with the robust ''

Paranthropus ''Paranthropus'' is a genus of extinct hominin which contains two widely accepted species: ''Paranthropus robustus, P. robustus'' and ''P. boisei''. However, the validity of ''Paranthropus'' is contested, and it is sometimes considered to be sy ...

'', it may not have been closely related because it lacked enlarged molars which are characteristic of ''Paranthropus''.

Anatomy

Despite being so early, the jaws of ''A. deyiremeda'' show some similarities to those of the 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 ...

'' and ''Paranthropus''. The jaw jutted out somewhat (

prognathism Prognathism, also called Habsburg jaw or Habsburgs' jaw primarily in the context of its prevalence amongst members of the House of Habsburg, is a positional relationship of the mandible or maxilla to the skeletal base where either of the jaws pr ...

) at perhaps a 39-degree angle, similar to most other early

s. The cheekbone is positioned more forward than most ''A. afarensis'' specimens. Unlike ''A. afarensis'' but like ''Paranthropus'', the walls of the

are inclined rather than coming straight up. The upper

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

are proportionally smaller than those of other ''Australopithecus'', but are otherwise morphologically similar to those of ''

A. anamensis ''Australopithecus anamensis'' is a hominin species that lived approximately between 4.2 and 3.8 million years ago and is the oldest known ''Australopithecus'' species, living during the Plio-Pleistocene era. Nearly one hundred fossil specimens ...

''. The cheek teeth are quite small for an early hominin, and the first molar is the smallest reported for an adult Pliocene hominin. Nonetheless, the enamel was still thick as other early hominins, and the enamel on the second molar is quite high and more similar to '' P. robustus''. The jawbone, though small, is robust and more similar to that of ''Paranthropus''. Burtele foot

In 2012, a 3.4-million-year-old partial foot, BRT-VP-2/73, was recovered from Woranso–Mille. It strongly diverges from contemporary and later hominins by having a dextrous big toe like the earlier '' Ardipithecus ramidus'', and consequently has not been assigned to a species. Though more diagnostic facial elements have since been discovered in the area, they are not clearly associated with the foot.

Palaeoecology

''A. deyiremeda'' features a strong jawbone and thick enamel, consistent with a diet of tough

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...

s and similar foods which australopiths are generally thought to have primarily subsisted upon. The enamel on the upper incisor, canine and first premolar exhibits

hypoplasia Hypoplasia (from Ancient Greek ὑπo- ''hypo-'' 'under' + πλάσις ''plasis'' 'formation'; adjective form ''hypoplastic'') is underdevelopment or incomplete development of a tissue or organ.enamel growth in infancy while the teeth were still growing. ''A. deyiremeda'' was likely a

generalist A generalist is a person with a wide array of knowledge on a variety of subjects, useful or not. It may also refer to: Occupations * a physician who provides general health care, as opposed to a medical specialist; see also: ** General pract ...

feeder. ''A. deyiremeda'' and ''A. afarensis'' may have exhibited niche partitioning given they cohabited the same area. That is, given dental and chewing differences, they may have had different dietary and/or habitat preferences, unless these differences were simply a product of

genetic drift Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and there ...

. Much like

chimpanzee The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative th ...

s and gorillas which have more or less the same diet and inhabit the same areas, ''A. deyiremeda'' and ''A. afarensis'' may have shared typical foods when in abundance, and resorted to different fallback foods in times of food scarcity. The

stone-tool industry from northern Kenya is loosely associated with the Middle Pliocene ''

'' based on an upper jaw fragment assigned to ''Kenyanthropus'' based on forward cheekbones, three-rooted premolars, and a small first molar. Since these features are also exhibited in ''A. deyiremeda'', anthropologist Fred Spoor suggested that ''A. deyiremeda'' was actually present at the site. Identified at 3.3 million years old, the Lomekwian is the earliest culture. These knappers

flaked ''Flaked'' is an American comedy drama streaming television series created by Will Arnett and Mark Chappell. It stars Arnett as Chip, a self-appointed "guru" who falls in love. The first season consisted of eight episodes and was released on Netfl ...

off pieces of cores made of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

phonolite Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous ...

and trachyphonolite. They held the core with one hand and struck it vertically with a

hammerstone In archaeology, a hammerstone is a hard cobble used to strike off lithic flakes from a lump of tool stone during the process of lithic reduction. The hammerstone is a rather universal stone tool which appeared early in most regions of the wo ...

, which is a simple process, though more complex than the tool-making behaviours of non-human primates. The Middle Pliocene of Woranso–Mille features

grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...

impala The impala or rooibok (''Aepyceros melampus'') is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus '' Aepyceros'' and tribe Aepycerotini, it was first described to European audiences by Germa ...

s, alcelaphins, and

elephants Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae and ...

, as well as browsing

giraffe The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, ''Giraffa camelopardalis ...

s, tragelaphins, and forest-dwelling

monkey Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, which constitutes an incomple ...

s. The feet of the

bovid The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, the ...

species do not seem to be specialised for any particular type of ground (such as wet, pliable, or hard), and the teeth of hoofed species indicates an equal abundance of grazers, browsers and mixed feeders. These suggest a mixed environment which features both open grasslands as well as forests probably growing on a lake- or riverside. Similar mosaic landscapes were inhabited by ''A. anamensis'' and ''A. afarensis'' who seem to have had no preferred environment.

References

External links

Human Timeline (Interactive)
– Smithsonian,

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...

(August 2016) {{Taxonbar, from=Q19991921 deyiremeda Pliocene primates Pliocene mammals of Africa Fossils of Ethiopia Mammals described in 2015 Fossil taxa described in 2015

Taxonomy

Anatomy

Palaeoecology

See also

References

External links