Sahelanthropus tchadensis Fossil range: Miocene
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Subfamily: Homininae Tribe: Hominini Subtribe: Hominina Genus: Sahelanthropus Brunet et al, 2002 Species: S. tchadensis
Binomial name
†Sahelanthropus tchadensis Brunet et al, 2002

Sahelanthropus tchadensis is a fossil ape, thought to have lived approximately 7 million years ago. It is sometimes claimed as the oldest known ancestor of Homo (humans) post-dating the most recent common ancestor of humans and chimpanzees. It was a species of Miocene ape, related to humans and other living African apes. The Miocene Epoch is a period of time that extends from about 23. ... Image File history File links SahelanthropustchadensisZICA.png I draw it on macromedia flash 24 oct 2005 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Typical Classes Subphylum Urochordata - Tunicates Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... Families 15, See classification A primate is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the latter category including humans. ... Genera The hominids are the members of the biological family Hominidae (the great apes), which includes humans, chimpanzees, gorillas, and orangutans. ... Tribes Gorillini Hominini and see text Homininae is a subfamily of Hominidae, including Homo sapiens and some extinct relatives, as well as the gorillas and the chimpanzees. ... Genera Subtribe Panina Pan (chimpanzees) Subtribe Hominina Homo (humans) †Paranthropus †Australopithecus †Sahelanthropus †Orrorin †Ardipithecus †Kenyanthropus For an explanation of very similar terms see Hominid Hominini is the tribe of Homininae that only includes humans (Homo), chimpanzees (Pan), and their extinct ancestors. ... Hominina is a subtribe that inludes Homo sapiens, Australopithecus, as well as prehistoric humans. ... Also see: 2002 (number). ... This article does not cite any references or sources. ... Also see: 2002 (number). ... For other uses, see Fossil (disambiguation). ... This article is about the biological superfamily. ... Species Homo sapiens See text for extinct species. ... This article is about modern humans. ... The most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended. ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species of apes in the genus Pan. ... The Miocene Epoch is a period of time that extends from about 23. ...

Fossils

Existing fossils, a relatively small cranium, five pieces of jaw, and some teeth, make up a head that has a mixture of derived and primitive features. The braincase, being only 340 cm³ to 360 cm³ in volume is similar to that of extant chimpanzees and is notably less than the approximate human volume of 1350 cm³. The teeth, brow ridges, and facial structure differ markedly from those found in Homo sapiens. Due to the distortion that the cranium has suffered, a 3D computer reconstruction has not been produced. Since no postcranial remains (bones below the skull) have been discovered, it is as of yet unknown whether Sahelanthropus tchadensis was indeed bipedal, although claims for an anteriorly placed foramen magnum suggests that this may have been the case, although some paleontologists have disputed this interpretation of the basicranium. Its canine wear is similar to other Miocene apes. Cranium can mean: The brain and surrounding skull, a part of the body. ... Human jaw front view Human jaw left view Human jaw top view The jaw is either of the two opposable structures forming, or near the entrance to, the mouth. ... Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... Homo sapiens (Latin: wise man) is the scientific name for the human species. ... In anatomy, in the occipital bone, the foramen magnum (Latin: great hole) is one of the several oval or circular apertures in the base of the skull (the foramina), through which the medulla oblongata (an extension of the spinal cord) enters and exits the skull vault. ...

The fossils were discovered in the desert of Chad by a team of four; three Chadians, Mahamat Adoum and Ahounta Djimdoumalbaye (who found the skull on July 19, 2001), Fanone Gongdibe, and Alain Beauvilain, the French team leader. All fossils of Sahelanthropus were found between July 2001 to March 2002. The discoverers claimed that S. tchadensis is the oldest known human ancestor after the split of the human line from that of chimpanzees. The bones were found in Chad, far from most previous hominin fossil finds, i.e. Eastern and Southern Africa. However, an australopithecine mandible was also found in Chad by Sahelanthropus' discoverers in 1993 belonging to Australopithecus bahrelghazali. is the 200th day of the year (201st in leap years) in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species of apes in the genus Pan. ... Genera Gorilla Pan (chimpanzees) Homo (humans) Paranthropus (extinct) Australopithecus (extinct) Sahelanthropus (extinct) Ardipithecus (extinct) Kenyanthropus (extinct) Homininae is a subfamily of Hominidae, including Homo sapiens and some extinct relatives, as well as the gorillas and the chimpanzees. ... Categories: Africa geography stubs | Eastern Africa ... Categories: Africa geography stubs | Southern Africa ... This term australopithecine refers to two very closely related hominin genera: Australopithecus Paranthropus When used alone, the term refers to both genera together. ... Year 1993 (MCMXCIII) was a common year starting on Friday (link will display full 1993 Gregorian calendar). ... Binomial name Australopithecus bahrelghazali Brunet et al. ...

Perspective

The fossil skull TM 266, nicknamed "Toumaï" ("hope of life" in the local Goran language of Chad), may be a common ancestor of humans and chimpanzees; most molecular clocks suggest humans and chimps diverged 1–2 million years after S. tchadensis (5 mya) but there is now general acceptance among paleontologists, and even among molecularists, that such a late divergence is no longer tenable. The original placement of this species as a human ancestor but not a chimpanzee ancestor complicated the picture of the human family tree. In particular, if Toumaï is a direct human ancestor, then its facial features bring the status of Australopithecus into doubt because its thickened brow ridges were reported to be similar to those of some later fossil hominids (notably Homo erectus), whereas this morphology differs from that observed in all australopithecines, most fossil hominids and extant humans. Dazaga, also known as Goran (Arabic قرعان), or Toubou, is a language spoken in the Djurab desert region of Chad by the Daza people, and is part of the Saharan branch of the Nilo-Saharan language family. ... A group of organisms is said to have common descent if they have a common ancestor. ... The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics, which researchers use to date when two species diverged. ... For other uses of mya, see mya (disambiguation). ... For the song by Modest Mouse, see Sad Sappy Sucker. ...

Another possibility is that Toumaï is related to both humans and chimpanzees, but is the ancestor of neither. Brigitte Senut and Martin Pickford, the discoverers of Orrorin tugenensis, suggested that the features of S. tchadensis are consistent with a female proto-gorilla. Even if this claim is upheld, then the find would lose none of its significance, for at present precious few chimpanzee or gorilla ancestors have been found anywhere in Africa. Thus if S. tchadensis is an ancestral relative of the chimpanzees (or gorillas) then the first light would be shed on their family trees. Furthermore, S. tchadensis does indicate that the last common ancestor of humans and chimpanzees is unlikely to resemble chimpanzees very much, as had been previously supposed by some paleontologists. Binomial name †Orrorin tugenensis Senut et al, 2001 Orrorin tugenensis is considered as the second oldest possible hominin ancestor related to modern humans (other than Sahelanthropus tchadensis) and is the only species classified in genus Orrorin. ... Type species Troglodytes gorilla Savage, 1847 distribution of Gorilla Species Gorilla gorilla Gorilla beringei The gorilla, the largest of the living primates, is a ground-dwelling omnivore that inhabits the forests of Africa. ...

See also

• Human evolution

For the history of humans on Earth, see History of the world. ...

References

• Michel Brunet, Franck Guy, David Pilbeam, Hassane Taisso Mackaye, Andossa Likius, Djimdoumalbaye Ahounta, et al. "A new hominid from the Upper Miocene of Chad, Central Africa". Nature, 418:145-51, 2002.
• Nature, "The look of Toumaï", 7 April 2005, pp. 752-755, ISSN 0028-0836
• Wolpoff, M.H., J. Hawks, B. Senut, M. Pickford, and J. Ahern: "An Ape or the Ape: Is the Toumaï Cranium TM 266 a Hominid?" PaleoAnthropology 2006:36-50. University of Wyoming news release and abstract

David Pilbeam 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. ... Nature is a prominent scientific journal, first published on 4 November 1869. ...

External links

Wikispecies has information related to:

Sahelanthropus

• Sahelanthropus.com
• [http://toumai.site.voila.fr/
• Fossil Hominids: Toumai
• National Geographic: Skull Fossil Opens Window Into Early Period of Human Origins
• image of the skull (nature.com)
• New Findings Bolster Case for Ancient Human Ancestor