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''Paranthropus aethiopicus'' is an
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), ...
of robust
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 ...
from the
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 ...
to
Early Pleistocene The Early Pleistocene is an unofficial epoch (geology), sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently esti ...
of East Africa about 2.7–2.3 million years ago. However, it is much debated whether or not ''Paranthropus'' is an invalid grouping and is
synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
with ''
Australopithecus ''Australopithecus'' (, ; or (, ) is a genus of early hominins that existed in Africa during the Pliocene and Early Pleistocene. The genera ''Homo'' (which includes modern humans), ''Paranthropus'', and ''Kenyanthropus'' evolved from some ''Aus ...
'', so the species is also often classified as ''Australopithecus aethiopicus''. Whatever the case, it is considered to have been the ancestor of the much more robust '' P. boisei''. It is debated if ''P. aethiopicus'' should be subsumed under ''P. boisei'', and the terms ''P. boisei''
sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...
("in the broad sense") and ''P. boisei''
sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
("in the strict sense") can be used to respectively include and exclude ''P. aethiopicus'' from ''P. boisei''. Like other ''Paranthropus'', ''P. aethiopicus'' had a tall face, thick
palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...
, and especially enlarged
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 ...
. However, likely due to its archaicness, it also diverges from other ''Paranthropus'', with some aspects resembling the much earlier '' A. afarensis''. ''P. aethiopicus'' is known primarily by the skull
KNM WT 17000 KNM-WT 17000 (also known as "The Black Skull") is a fossilized adult skull of the species '' Paranthropus aethiopicus''. It was discovered in West Turkana, Kenya by Alan Walker in 1985. Estimated to be 2.5 million years old, the fossil is an ...
from West Turkana,
Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
, as well as some jawbones from Koobi Fora; the Shungura Formation, Ethiopia; and
Laetoli Laetoli is a pre-historic site located in Enduleni ward of Ngorongoro District in Arusha Region, Tanzania. The site is dated to the Plio-Pleistocene and famous for its Hominina footprints, preserved in volcanic ash. The site of the Laetoli footp ...
, Tanzania. These locations featured bushland to open woodland landscapes with edaphic (water-logged) grasslands.


Taxonomy


Research history

In 1968, French palaeontologist
Camille Arambourg Camille Arambourg (February 3, 1885 – November 19, 1969) was a French vertebrate paleontologist. He conducted extensive field work in North Africa. In the 1950s, he argued against the prevailing model of Neanderthals as brutish and simian. Du ...
and Breton anthropologist Yves Coppens described "''Paraustralopithecus aethiopicus''" based on a toothless mandible (Omo 18) from the Shungura Formation, Ethiopia. The name ''aethiopicus'' refers to Ethiopia. In 1976, American anthropologist Francis Clark Howell and Coppens reclassified it as ''A. africanus''. In 1985, the skull KNM WT 17000 dating to 2.5 million years ago was reported from
Koobi Fora Koobi Fora refers primarily to a region around Koobi Fora Ridge, located on the eastern shore of Lake Turkana in the territory of the nomadic Gabbra people. According to the National Museums of Kenya, the name comes from the Gabbra language ...
,
Lake Turkana Lake Turkana () is a saline lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world ...
, Kenya, by anthropologists
Alan Walker Alan Olav Walker (born 24 August 1997) is a Norwegian DJ and record producer. His songs "Faded (Alan Walker song), Faded", "Sing Me to Sleep", "Alone (Alan Walker song), Alone", "All Falls Down (Alan Walker song), All Falls Down" (with Noah Cy ...
and
Richard Leakey Richard Erskine Frere Leakey (19 December 1944 – 2 January 2022) was a Kenyan paleoanthropologist, conservationist and politician. Leakey held a number of official positions in Kenya, mostly in institutions of archaeology and wildlife cons ...
. A partial jawbone from a different individual, KNM-WT 16005, was also discovered. They clearly belonged to a robust
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 ...
. By this point in time, much younger robust australopithecines had been reported from South Africa ('' robustus'') and East Africa ('' boisei''), and been variously assigned to either ''
Australopithecus ''Australopithecus'' (, ; or (, ) is a genus of early hominins that existed in Africa during the Pliocene and Early Pleistocene. The genera ''Homo'' (which includes modern humans), ''Paranthropus'', and ''Kenyanthropus'' evolved from some ''Aus ...
'' or a unique genus ''
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 ...
''. Walker and Leakey assigned KNM WT 17000 to the ''boisei''
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
. They noted several anatomical differences, but were unsure if this stemmed from the specimens' archaicness or represented the normal range of variation for the species. If the former, they recommended classifying them and similar specimens into a different species, ''aethiopicus'' (and recommended that ''Paraustralopithecus'' be invalid). The discovery of these archaic specimens overturned previous postulations that ''P. robustus'' was the ancestor of the much more robust ''P. boisei'' (a hypothesis notably argued by palaeoanthropologist in 1985) by establishing the ''boisei'' lineage as beginning long before ''robustus'' had existed. In 1989, palaeoartist Walter Ferguson recommended KNM WT 17000 be classified into a different species, ''walkeri'', because the holotype of ''aethiopicus'' comprised only the jawbone and KNM WT 17000 preserves no jaw elements. Ferguson's classification is almost universally ignored, and is considered to be synonymous with ''P. aethiopicus''. Several more lower and upper jaw specimens have been unearthed in the Shungura Formation, including a juvenile specimen, L338y-6. In 2002, a 2.7–2.5 Ma
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 ...
, EP 1500, from
Laetoli Laetoli is a pre-historic site located in Enduleni ward of Ngorongoro District in Arusha Region, Tanzania. The site is dated to the Plio-Pleistocene and famous for its Hominina footprints, preserved in volcanic ash. The site of the Laetoli footp ...
, Tanzania, was assigned to ''P. aethiopicus''. Also found was the upper portion of a
tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...
, but it cannot definitively be associated with EP 1500 and thus with ''P. aethiopicus''.


Classification

The genus ''Paranthropus'' (from
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
παρα ''para'' beside or alongside, and άνθρωπος ''ánthropos'' man, otherwise known as "robust australopithecines") typically includes ''P. aethiopicus'', ''P. boisei'', and ''P. robustus''. ''P. aethiopicus'' is the earliest member of the genus, with the oldest remains, from the Ethiopian
Omo Kibish Formation The Omo Kibish Formation or simply Kibish Formation is a geological formation in the Lower Omo Valley of southwestern Ethiopia. It is named after the nearby Omo River (Ethiopia), Omo River and is subdivided into four members known as Members I-IV. ...
, dated to 2.6 million years ago (mya) at the end of the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58KNM WT 17000 KNM-WT 17000 (also known as "The Black Skull") is a fossilized adult skull of the species '' Paranthropus aethiopicus''. It was discovered in West Turkana, Kenya by Alan Walker in 1985. Estimated to be 2.5 million years old, the fossil is an ...
and a few jaws and isolated teeth, and is generally considered to have been ancestral to ''P. boisei'' which also inhabited East Africa, making it a
chronospecies A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is p ...
. Because of this relationship, it is debatable if ''P. aethiopicus'' should be subsumed under ''P. boisei'' or if the differences stemming from archaicness should justify species distinction. The terms ''P. boisei
sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...
'' ("in the broad sense") and ''P. boisei
sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
'' ("in the strict sense") can be used to respectively include and exclude ''P. aethiopicus'' from ''P. boisei'' when discussing the lineage as a whole. It is also debated if ''Paranthropus'' is a valid natural grouping (
monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...
) or an invalid grouping of similar-looking hominins (
paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
). Because skeletal elements are so limited in these species, their affinities with each other and to other australopithecines is difficult to gauge with accuracy. The jaws are the main argument for monophyly, but such anatomy is strongly influenced by diet and environment, and could in all likelihood have evolved independently in ''P. boisei'' and ''P. robustus''. Proponents of monophyly consider ''P. aethiopicus'' to be ancestral to the other two species, or closely related to the ancestor. Proponents of paraphyly allocate these three species to the genus ''Australopithecus'' as ''A. boisei'', ''A. aethiopicus'', and ''A. robustus''. British geologist Bernard Wood and American palaeoanthropologist William Kimbel are major proponents of monophyly, and against include Walker. This species, originally named ''Paraustralopithecus aethiopicus'', cannot retain the species epithet ''aethiopicus'' if moved to genus ''Australopithecus'' because ''Australopithecus aethiopicus'' is already a
junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...
of ''
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 ...
''. Such a classification would have to use the name ''Australopithecus walkeri'' for this species. The change of species epithet would also happen in a taxonomy that classifies all hominins as ''Homo''.


Description

Typical of ''Paranthropus'', KNM WT 17000 is heavily built, and the
palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...
and
base of the skull The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria. Structure Structures found at the base of the skull are for ...
are about the same size as the ''P. boisei'' holotype
OH 5 ''Paranthropus boisei'' is a species of australopithecine from the Early Pleistocene of East Africa about 2.5 to 1.15 million years ago. The holotype specimen, OH 5, was discovered by palaeoanthropologist Mary Leakey in 1959 at Olduvai Gorge, T ...
. The brain volume of KNM WT 17000 was estimated to have been , which is smaller than that of other ''Paranthropus''. The combination of a tall face, thick palate, and small braincase caused a highly defined
sagittal crest A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are excepti ...
on the midline of the skull. The only complete tooth crown of the specimen is the right third
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 ...
, whose dimensions are well above the range of variation for ''P. robustus'' and on the upper end for ''P. boisei''. Unlike other ''Paranthropus'', KNM WT 17000 did not have a flat face, and the jaw jutted out (
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 ...
). In regard to the
temporal bone The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bone ...
, KNM WT 17000 differs from other ''Paranthropus'' in that the squamous part of temporal bone is extensively pneumaticised, the
tympanic part of the temporal bone The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal. It originates as a separate bone (tympan ...
is not as vertically orientated, the base of the skull is weakly flexed, the postglenoid process is completely anterior to (in front of) the tympanic, the tympanic is somewhat tubular, and the articular tubercle is weak. Like ''P. boisei'', the
foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...
where the skull connects to the
spine Spine or spinal may refer to: Science Biology * Spinal column, also known as the backbone * Dendritic spine, a small membranous protrusion from a neuron's dendrite * Thorns, spines, and prickles, needle-like structures in plants * Spine (zoology), ...
is heart-shaped. The
temporalis muscle In anatomy, the temporalis muscle, also known as the temporal muscle, is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head that fills the temporal fossa, superior to the zygomatic a ...
was probably not directed as forward as it was in ''P. boisei'', meaning the ''P. aethiopicus'' jaw likely processed food with the
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 ...
s before using the cheek teeth. The incisors of ''P. boisei'' are thought to have not been involved in processing food. The long distance between the first molar and the jaw hinge would suggest KNM WT 17000 had an exceptionally long
ramus of the mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...
(connecting the lower jaw to the skull), though the hinge's location indicates the ramus would not have been particularly deep (it would have been weaker). This may have produced a less effective bite compared to ''P. boisei''. KNM-WT 16005 is quite similar to the Peninj Mandible assigned to ''P. boisei'', exhibiting postcanine megadontia with relatively small incisors and canines (based on the tooth roots) and large
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 ...
. Nonetheless, the incisors were likely much broader in KNM-WT 16005. KNM-WT 16005 preserved four cheek teeth on the left side: the third premolar measuring , the fourth premolar measuring , the first molar measuring , and the second molar measuring . The fourth premolar and first molar are a little smaller than those of the Peninj mandible, and the second molar a bit bigger. The KNM-WT 16005 jawbone is smaller than what KNM WT 17000 would have had. Many of these ''P. aethiopicus'' features are shared with the early '' A. afarensis'', further reiterating the species' archaicness.


Palaeoecology

In general, ''Paranthropus'' are thought to have been generalist feeders, with the heavily built skull becoming important when chewing less desirable, lower quality foods in times of famine. Unlike ''P. boisei'' which generally is found in the context of closed, wet environments, ''P. aethiopicus'' seems to have inhabited bushland to open woodland habitats around edaphic (water-logged) grasslands. Around 2.5 million years ago, at the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
border, the Omo–Turkana Basin featured a mix of forests, woodlands, grasslands, and bushlands, though grasslands appear to have been expanding through the
Early Pleistocene The Early Pleistocene is an unofficial epoch (geology), sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently esti ...
. ''
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 ...
'' seems to have entered the region 2.5–2.4 million years ago.


See also

* * * * * * * * *


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=Q310517 Paranthropus Pliocene primates Fossil taxa described in 1968 Prehistoric Kenya Pleistocene mammals of Africa Pleistocene primates