''Australopithecus bahrelghazali'' 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
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 ...
discovered in 1995 at
Koro Toro,
Bahr el Gazel, Chad, existing around 3.5 million years ago in the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58[Central Africa
Central Africa (French language, French: ''Afrique centrale''; Spanish language, Spanish: ''África central''; Portuguese language, Portuguese: ''África Central'') is a subregion of the African continent comprising various countries accordin ...](_blank)
, and demonstrates that this group was widely distributed across Africa as opposed to being restricted to East and southern Africa as previously thought. The validity of ''A. bahrelghazali'' has not been widely accepted, in favour of classifying the specimens as ''
A. afarensis'', a better known Pliocene australopithecine from East Africa, because of the anatomical similarity and the fact that ''A. bahrelghazali'' is known only from 3 partial jawbones and an isolated
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 ...
. The specimens inhabited a lakeside grassland environment with sparse tree cover, possibly similar to the modern
Okavango Delta, and similarly predominantly ate
C4 savanna foods—such as grasses, sedges,
storage organ
A storage organ is a part of a plant specifically modified for storage of energy
(generally in the form of carbohydrates) or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have ...
s, or
rhizome
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...
s—and to a lesser degree also
C3 forest foods—such as fruits, flowers, pods, or insects. However, the teeth seem ill-equipped to process C
4 plants, so its true diet is unclear.
Research history
In 1995, two specimens were recovered from
Koro Toro,
Bahr el Gazel, Chad: KT12/H1 or "
Abel
Abel ( ''Hébel'', in pausa ''Hā́ḇel''; ''Hábel''; , ''Hābēl'') is a biblical figure in the Book of Genesis within the Abrahamic religions. Born as the second son of Adam and Eve, the first two humans created by God in Judaism, God, he ...
" (a jawbone preserving the premolars,
canines, and the right second
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 KT12/H2 (an isolated first upper
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 ...
). They were discovered by the Franco-Chadian Paleoanthropological Mission, and reported by French palaeontologist
Michel Brunet Michel Brunet may refer to:
* Michel Brunet (historian) (1917–1985), Canadian historian
* Michel Brunet (paleontologist)
Michel Brunet (born April 6, 1940) is a French paleontologist and a professor at the Collège de France between 2008 and 20 ...
, French geographer Alain Beauvilain, French anthropologist
Yves Coppens, French palaeontologist Emile Heintz, Chadian geochemist engineer Aladji Hamit Elimi Ali Moutaye, and British palaeoanthropologist
David Pilbeam
David Pilbeam (born 21 November 1940 in Brighton, Sussex, England) is the Henry Ford II Professor of the Social Sciences at Harvard University and curator of paleoanthropology at the Peabody Museum of Archaeology and Ethnology. He is a member of ...
. Based on the wildlife assemblage, the remains were roughly dated to the middle to late
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58[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 ...](_blank)
'', which inhabited Ethiopia during that time period, barring more detailed anatomical comparisons.
In 1996, they allocated it to a new species, ''A. bahrelghazali'', naming it after the region; Bahr el Gazel means "River of the Gazelles" in
classical Arabic
Classical Arabic or Quranic Arabic () is the standardized literary form of Arabic used from the 7th century and throughout the Middle Ages, most notably in Umayyad Caliphate, Umayyad and Abbasid Caliphate, Abbasid literary texts such as poetry, e ...
. They denoted KT12/H1 as 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 ...
and KT12/H2 a
paratype
In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...
. Another jawbone was discovered at the K13 site in 1997, and a third from the KT40 site.
In 2008, a
pelite
A pelite () or metapelite is a metamorphism, metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or ...
(a type of
sedimentary rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
) recovered from the same sediments as Abel was
radiometrically dated (using the
10Be/
9Be ratio) to have been deposited 3.58 million years ago. However, Beauvilain responded that Abel was not found ''
in situ
is a Latin phrase meaning 'in place' or 'on site', derived from ' ('in') and ' ( ablative of ''situs'', ). The term typically refers to the examination or occurrence of a process within its original context, without relocation. The term is use ...
'' but at the edge of a shallow gulley, and it is impossible to figure out from what
stratigraphic section
A stratigraphic section is a sequence of layers of rocks in the order they were deposited. It is based on the principle of original horizontality, which states that layers of sediment are originally deposited horizontally under the action of ...
the specimen (or any other fossil from Koro Toro) was first deposited in, in order to accurately radiometrically date it. Nonetheless, Abel was redated in 2010 using the same methods to about 3.65 million years ago, and Brunet agreed with an age of roughly 3.5 million years ago.
[
''A. bahrelghazali'' was the first ]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 ...
recovered from Central Africa, and disproved the earlier notion that they were restricted to east of the eastern branch of the East African Rift
The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a l ...
which formed in the Late Miocene
The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
. Koro Toro is situated about from the Rift Valley, and the remains suggest australopithecines were widely distributed in grassland and woodland zones across the continent. The lack of other Central and West African australopithecines may be due to sampling bias
In statistics, sampling bias is a bias (statistics), bias in which a sample is collected in such a way that some members of the intended statistical population, population have a lower or higher sampling probability than others. It results in a b ...
, as similarly aged fossil-bearing sediments are more or less unknown beyond East Africa.[ The ancestors of ''A. bahrelghazali'' may have left East Africa via the ]Central African Shear Zone
The Central African Shear Zone (CASZ) (or Shear System) is a wrench fault system extending in an ENE direction from the Gulf of Guinea through Cameroon into Sudan.
The structure is not well understood.
, there was still no general agreement about ...
.[ In 2014, the first australopithecine in the western branch of the East African Rift was reported in ]Ishango
Ishango is a Congolese lakeshore site located in the north-eastern region of the Democratic Republic of Congo in Africa, previously known as Zaire. This present day village is known as a "fishermen settlement" as it lies on the shores of the Seml ...
, Democratic Republic of the Congo.
At present, the classification of ''Australopithecus'' and ''Paranthropus'' species is in disarray. ''Australopithecus'' is considered a grade taxon whose members are united by their similar physiology rather than how close they are to each other in the hominin family tree. In an attempt to resolve this, in 2003, Spanish writer Camilo José Cela Conde
Camilo José Arcadio Cela Conde, 2nd Marquess of Iria Flavia (born 17 January 1946), is a Spanish writer. He is the son of Nobel Prize in Literature, Nobel Prize winning writer Camilo José Cela and is currently a Professor (highest academic ran ...
and evolutionary biologist Francisco J. Ayala
Francisco José Ayala Pereda (March 12, 1934 – March 3, 2023) was a Spanish-American evolutionary biologist and philosopher who was a longtime faculty member at the University of California, Irvine, and University of California, Davis.
Ayal ...
proposed splitting off the genus "''Praeanthropus''" and including ''A. bahrelghazali'' alongside ''Sahelanthropus
''Sahelanthropus'' is an extinct genus of hominid dated to about during the Late Miocene. The type species, ''Sahelanthropus tchadensis'', was first announced in 2002, based mainly on a partial cranium, nicknamed ''Toumaï'', discovered in north ...
'' (the only other fossil ape known from Chad), '' A. anamensis'', ''A. afarensis'', and '' A. garhi''.
The validity of ''A. bahrelghazali'' has not been widely accepted given how few remains there are and how similar they are to ''A. afarensis''.
Anatomy
The teeth of KT12/H1 are quite similar to the jawbone of ''A. afarensis'', with large and incisor-like canines and bicuspid premolars (as opposed to molar-like premolars). Unlike ''A. afarensis'', the alveolar part of the jawbone where the tooth socket
Dental alveoli (singular ''alveolus'') are sockets in the jaws in which the roots of teeth are held in the alveolar process with the periodontal ligament. The lay term for dental alveoli is tooth sockets. A joint that connects the roots of the t ...
s are is almost vertical as opposed to oblique, possesses poorly developed superior transverse torus and moderate inferior torus (two ridges on the midline of the jaw on the tongue side), and thin enamel on the chewing surface of the premolars.[ Brunet and colleagues had listed the presence of 3 distinct tooth roots as a distinguishing characteristic, but the third premolar of the ''A. afarensis'' LH-24 specimen from Middle Awash, Ethiopia, was described in 2000 as having the same feature, which shows that premolar anatomy was highly variable for ''A. afarensis''. The ]mandibular symphysis
In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...
(at the midline of the jaw) of KT40, especially, as well as KT12/H1 have the same dimensions as the symphysis of ''A. afarensis'', though theirs is relatively thick compared to the height.[
]
Palaeoecology
Carbon isotope analysis indicates a diet of predominantly C4 savanna foods, such as grasses, sedges, underground storage organ
A storage organ is a part of a plant specifically modified for storage of energy
(generally in the form of carbohydrates) or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have ...
s (USOs), or rhizome
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...
s. There is a smaller C3 portion which may have comprised more typical ape food items such as fruits, flowers, pods, or insects. This indicates that, like contemporary and future australopiths, ''A. bahrelghazali'' was capable of exploiting whatever food was abundant in its environment, whereas most primates (including savanna chimps) avoid C4 foods. However, despite 55–80% of δ13C deriving from C4 sources similar to ''Paranthropus boisei
''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, Ta ...
'' and the modern gelada (and considerably more than any tested ''A. afarensis'' population), ''A. bahrelghazali'' lacks the specialisations for such a diet. Because the teeth are not hypsodont
Hypsodont is a pattern of dentition characterized by with high crowns, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cows and horses; all animals that feed on gritty, fibrous material. The oppos ...
, it could not have chewed large quantities of grass, and because the enamel is so thin, the teeth would not have been able to withstand the abrasive dirt particles of USOs. In regard to C4 sources, chimps and bonobo
The bonobo (; ''Pan paniscus''), also historically called the pygmy chimpanzee (less often the dwarf chimpanzee or gracile chimpanzee), is an endangered great ape and one of the two species making up the genus ''Pan (genus), Pan'' (the other bei ...
s (which have even thinner enamel) consume plant medullas as a fallback food and sedges as an important energy and protein source; however a sedge-based diet likely could not have sustained ''A. bahrelghazali''.
During the Pliocene around the expanded Lake Chad
Lake Chad (, Kanuri language, Kanuri: ''Sádǝ'', ) is an endorheic freshwater lake located at the junction of four countries: Nigeria, Niger, Chad, and Cameroon, in western and central Africa respectively, with a catchment area in excess of . ...
(or "Lake Mega-Chad"), insect trace fossil
A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...
s indicate this was a well-vegetated region, and the abundance of rhizome
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...
s may suggest a seasonal climate with wet and dry seasons. Koro Toro has yielded several large mammals, including several antelope
The term antelope refers to numerous extant or recently extinct species of the ruminant artiodactyl family Bovidae that are indigenous to most of Africa, India, the Middle East, Central Asia, and a small area of Eastern Europe. Antelopes do ...
s, of which some were endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
, the elephant
Elephants are the 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 elephant ('' Elephas maximus ...
'' Loxodonta exoptata'', the white rhinoceros
The white rhinoceros, also known as the white rhino or square-lipped rhinoceros (''Ceratotherium simum''), is the largest extant species of rhinoceros and the most Sociality, social of all rhino species, characterized by its wide mouth adapted f ...
'' Ceratotherium praecox'', the pig
The pig (''Sus domesticus''), also called swine (: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus '' Sus''. Some authorities cons ...
'' Kolpochoerus afarensis'', a ''Hipparion
''Hipparion'' is an extinct genus of three-toed, medium-sized equine belonging to the extinct tribe Hipparionini, which lived about 10-5 million years ago. While the genus formerly included most hipparionines, the genus is now more narrowly defi ...
'' horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...
, a ''Sivatherium
''Sivatherium'' ("Shiva's beast", from Shiva and ''therium'', Latinized form of Ancient Greek θηρίον -'' thēríon'') is an extinct genus of giraffid that ranged throughout Africa and Eurasia. The species ''Sivatherium giganteum'' is, by ...
'', and a 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 ...
. Some of these are also known from Pliocene East African sites, implying that animals could freely migrate between east and west of the Great African Rift.[ The K13 site features, in regard to ]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 ...
s, an abundance of Reduncinae, Alcelaphinae
The subfamily Alcelaphinae (or Tribe (biology), tribe Alcelaphini), of the family Bovidae, contains the wildebeest, tsessebe, topi, hartebeest, blesbok and bontebok, and several other related species. Depending on the classification, there are 6� ...
, and Antilopinae, whereas Tragelaphini
The tribe Tragelaphini (referred to by some authors as "Strepsicerotini"), or the spiral-horned antelopes, are bovines that are endemic to sub-Saharan Africa. These include the bushbucks, kudus, and the elands. The scientific name is in referen ...
is much rarer, which indicates an open environment which was drier than Pliocene East African sites. In total, the area seems to have been predominantly grasslands with some tree cover.[ In addition, the area featured aquatic creatures, predominantly ]catfish
Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...
, and also 10 other kinds of fish, the hippo
The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic Mammal, mammal native to su ...
'' Hexaprotodon protamphibius'', an otter
Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine. Lutrinae is a branch of the Mustelidae family, which includes weasels, badgers, mink, and wolverines, among ...
, a ''Geochelone
''Geochelone'', from Ancient Greek γῆ (''gê''), meaning "earth", and χελώνη (''khelṓnē''), meaning "turtle", is a genus of tortoises.
''Geochelone'' tortoises, which are also known as typical tortoises or terrestrial turtles, can be ...
'' tortoise
Tortoises ( ) are reptiles of the family Testudinidae of the order Testudines (Latin for "tortoise"). Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like o ...
, a '' Trionyx'' softshell turtle
Trionychidae is a family of turtles, commonly known as softshell turtles or simply softshells. The family was described by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to li ...
, a false gharial
The false gharial (''Tomistoma schlegelii''), also known by the names Malayan gharial, Sunda gharial and tomistoma is a freshwater crocodilian of the Family (biology), family Gavialidae native to Peninsular Malaysia, Borneo, Sumatra and Java. It ...
, and an anatid waterbird
A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...
. These aquatic animals indicate Koro Toro had open-water lakes or streams with swampy grassy margins, connected to the Nilo-Sudan waterways (including the Nile
The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the List of river sy ...
, Chari, Niger
Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...
, Senegal
Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...
, Volta, and Gambia
The Gambia, officially the Republic of The Gambia, is a country in West Africa. Geographically, The Gambia is the List of African countries by area, smallest country in continental Africa; it is surrounded by Senegal on all sides except for ...
Rivers). Koro Toro, during Mega-Chad events (which have been cyclical for the last 7 million years), may have been similar to the modern Okavango Delta.
See also
* African archaeology
Africa has the longest record of human habitation in the world. The first hominins emerged 6–7 million years ago, and among the earliest anatomically modern human skulls found so far were discovered at Omo remains, Omo Kibish,Jebel Irhoud, and F ...
* '' Ardipithecus ramidus''
* ''Australopithecus anamensis
''Australopithecus anamensis'' is a hominin species that lived roughly between 4.3 and 3.8 million years ago, and is the oldest known ''Australopithecus'' species,
Nearly 100 fossil specimens of ''A. anamensis'' are known from Kenya and Ethiopia ...
''
* ''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 ...
''
* ''Australopithecus deyiremeda
''Australopithecus deyiremeda'' is an extinct species of australopithecine from Woranso–Mille, Afar Region, Ethiopia, about 3.5 to 3.3 million years ago during the Pliocene. Because it is known only from three partial jawbones, it is unclear ...
''
* ''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 ...
''
* List of fossil sites
This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there. Many of ...
(with link directory)
* List of human evolution fossils
The following tables give an overview of notable finds of Hominini, hominin fossils and Skeleton, remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the Chimpanzee–human last common ancest ...
(with images)
References
External links
''Australopithecus bahrelghazali'', Abel
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=Q310945
Australopithecus
Fossil taxa described in 1995
Prehistoric Chad
Pliocene primates
Pliocene mammals of Africa