extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

australopithecine The australopithecines (), formally Australopithecina or Hominina, are generally any species in the related genera of ''Australopithecus'' and ''Paranthropus''. It may also include members of '' Kenyanthropus'', ''Ardipithecus'', and '' Praeant ...

Afar Region The Afar Region (; ; ), formerly known as Region 2, is a Regions of Ethiopia, 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 Awash, Ethiopia, Awash� ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58A. afarensis''. ''A. deyiremeda'' is distinguished by its forward-facing cheek bones and small

cheek teeth Cheek teeth or postcanines 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 (hominins) form a taxonomic tribe of the subfamily Homininae (hominines). They comprise two extant genera: ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos), and in standard usage exclude the genus '' Gorilla'' ( gorillas) ...

s. It is unclear if a partial foot specimen exhibiting a dextrous big toe (a characteristic unknown in any australopithecine) 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 is an archaeological site located on the west bank of Turkana Lake in Kenya. It is an important milestone in the history of human archaeology. An archaeological team from Stony Brook University in the United States discovered traces o ...

stone-tool

industry Industry may refer to: Economics * Industry (economics), a generally categorized branch of economic activity * Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery * The wider industrial sector ...

typically assigned to ''

Kenyanthropus ''Kenyanthropus'' is a genus of extinct hominin 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 mi ...

''. ''A. deyiremeda'' coexisted with ''A. afarensis'', and they may have exhibited

niche partitioning In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for e ...

to avoid competing 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 Yohannes Haile-Selassie Ambaye (born 23 February 1961) is an Ethiopian Paleoanthropology, paleoanthropologist. An authority on pre-''Homo sapiens'' hominids, he particularly focuses his attention on the East African Rift and Middle Awash valleys. ...

and colleagues based on jawbone fossils from the Burtele and Waytaleyta areas of Woranso–Mille,

Afar Region The Afar Region (; ; ), formerly known as Region 2, is a Regions of Ethiopia, 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 Awash, Ethiopia, Awash� ...

, Ethiopia. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen, a young adult left

maxilla In vertebrates, the maxilla (: maxillae ) 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 two maxil ...

with all teeth except the first

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

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 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 Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

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 to 3.5–3.3 million years ago, the Middle Pliocene. The describers believed the remains were distinct enough from the contemporary and well-known '' A. afarensis'' to warrant species distinction, and ''A. deyiremeda'' is counted among a growing diversity of

Late Pliocene Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * Late (The 77s album), ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudo ...

australopithecine The australopithecines (), formally Australopithecina or Hominina, are generally any species in the related genera of ''Australopithecus'' and ''Paranthropus''. It may also include members of '' Kenyanthropus'', ''Ardipithecus'', and '' Praeant ...

s alongside ''A. afarensis'', '' A. bahrelghazali'' and '' Kenyanthropus platyops''. The name ''deyiremeda'' derives from the

Afar language Afar is an Afroasiatic language belonging to the Cushitic branch, primarily spoken by the Afar people, native to parts of Djibouti, Eritrea and Ethiopia. It is an official language in Ethiopia; and a national language in Djibouti and Eritre ...

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 a result at least as "extreme" would be very infrequent if the null hypothesis were true. More precisely, a study's defined significance level, denoted by \alpha, is the ...

, 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 a genus of great ape (family Hominidae) that emerged from the genus ''Australopithecus'' and encompasses only a single extant species, ''Homo sapiens'' (modern humans), along with a number of extinct species (collectively called ...

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

prognathism Prognathism is a positional relationship of the mandible or maxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in the coronal plane of the skull. In the case of ''mandibular'' prognathism (nev ...

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

hominin The Hominini (hominins) form a taxonomic tribe of the subfamily Homininae (hominines). They comprise two extant genera: ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos), and in standard usage exclude the genus '' Gorilla'' ( gorillas) ...

s. The cheekbone is positioned more forward than most ''A. afarensis'' specimens. Unlike ''

Australopithecus 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 ...

'' but like ''Paranthropus'', the walls of the

cheek teeth Cheek teeth or postcanines 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 ...

are inclined rather than coming straight up. The upper canines are proportionally smaller than those of other ''Australopithecus'', but are otherwise morphologically similar to those of '' A. anamensis''. 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 wikt:sedge, sedges. The family (biology), family is large; botanists have species description, described some 5,500 known species in about 90 ...

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 (; 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 feeder. ''A. deyiremeda'' and ''A. afarensis'' may have exhibited

niche partitioning In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for e ...

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 random genetic drift, allelic drift or the Wright effect, is the change in the Allele frequency, frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene va ...

. Much like

chimpanzee The chimpanzee (; ''Pan troglodytes''), also simply known as the chimp, is a species of Hominidae, great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close rel ...

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

Lomekwi Lomekwi is an archaeological site located on the west bank of Turkana Lake in Kenya. It is an important milestone in the history of human archaeology. An archaeological team from Stony Brook University in the United States discovered traces o ...

stone-tool

industry Industry may refer to: Economics * Industry (economics), a generally categorized branch of economic activity * Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery * The wider industrial sector ...

from northern Kenya is loosely associated with the Middle Pliocene ''

Kenyanthropus ''Kenyanthropus'' is a genus of extinct hominin 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 mi ...

'' 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 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 shallow intrusive or 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 var ...

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 free range (roam around) and consume wild vegetations in order to feed conversion ratio, convert the otherwise indigestible (by human diges ...

impala The impala or rooibok (''Aepyceros melampus'', lit. 'black-footed high-horn' in Ancient Greek) is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus '' Aepyceros'', and tribe Aepycerotini, it ...

s, alcelaphins, and

elephants Elephants are the Largest and heaviest animals, largest living land animals. Three living species are currently recognised: the African bush elephant (''Loxodonta africana''), the African forest elephant (''L. cyclotis''), and the Asian ele ...

, as well as

browsing Browsing is a kind of orienting strategy. It is supposed to identify something of relevance for the browsing organism. In context of humans, it is a metaphor taken from the animal kingdom. It is used, for example, about people browsing open sh ...

giraffe The giraffe is a large Fauna of Africa, African even-toed ungulate, hoofed mammal belonging to the genus ''Giraffa.'' It is the Largest mammals#Even-toed Ungulates (Artiodactyla), tallest living terrestrial animal and the largest ruminant on ...

s, tragelaphins, and forest-dwelling

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

s. The feet of the

bovid The Bovidae comprise the family (biology), biological family of cloven-hoofed, ruminant mammals that includes Bos, cattle, bison, Bubalina, buffalo, antelopes (including Caprinae, goat-antelopes), Ovis, sheep and Capra (genus), goats. A member o ...

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 (NMNH) 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. With 4.4 ...

(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