| Australopithecines | |
|---|---|
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| Australopithecus sediba | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Primates |
| Suborder: | Haplorhini |
| Family: | Hominidae |
| Tribe: | Hominini |
| Subtribe: | Australopithecina Gregory & Hellman, 1939 |
| Type species | |
| †Australopithecus africanus Dart, 1925 | |
| Genera | |
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| Synonyms | |
Theaustralopithecines (/ɒˈstrəloʊˈpɪθəsiːnz,ˈɔːstreɪloʊ-/),[4][5][6] formallyAustralopithecina orHominina, are generally any species in the relatedgenera ofAustralopithecus andParanthropus. It may also include members ofKenyanthropus,[7]Ardipithecus,[7] andPraeanthropus.[8] The term comes from a former classification as members of a distinct subfamily, the Australopithecinae.[9] They are classified within theAustralopithecina subtribe of theHomininitribe.[10][11] These related species are sometimes[dubious –discuss] collectively termedaustralopithecines,australopiths, orhomininians. They are the extinct, close relatives of modern humans and, together with the extant genusHomo, comprise the humanclade. Members of the human clade, i.e. the Hominini after the split from the chimpanzees, are called Hominina[12] (see Hominidae;terms "hominids" and hominins).
While none of the groups normally directly assigned to this group survived, the australopithecines do not appear to be literally extinct (in the sense of having no living descendants) as the generaKenyanthropus,Paranthropus, andHomo probably emerged as sisters of a lateAustralopithecus species such asA. africanus and/orA. sediba.
The terms australopithecines, et. al., come from a former classification as members of a distinct subfamily, the Australopithecinae.[9] Members ofAustralopithecus are sometimes referred to as the "gracile australopithecines", whileParanthropus are called the "robust australopithecines".[13][14]
The australopithecines occurred in theLate Miocene sub-epoch and werebipedal, and they were dentally similar to humans, but with a brain size not much larger than that of modern non-humanapes, with lesserencephalization than in the genusHomo.[15] Humans (genusHomo) may have descended from australopithecine ancestors and thegeneraArdipithecus,Orrorin,Sahelanthropus, andGraecopithecus are the possible ancestors of the australopithecines.[14]
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Classification of subtribe Australopithecina according toBriggs & Crowther 2008, p. 124.
Phylogeny of Hominina/Australopithecina according to Demboet al. (2016).[16]
The post-cranial remains of australopithecines show they were adapted tobipedal locomotion, but did not walk identically to humans. They had a forearm to upper arm ratio similar to theGolden Ratio[17][18] – greater than other hominins. They exhibited greatersexual dimorphism than members ofHomo orPan but less so thanGorilla orPongo. It is thought that they averaged heights of 1.2–1.5 metres (3.9–4.9 ft) and weighed between 30 and 55 kilograms (66 and 121 lb). Thebrain size may have been 350 cc to 600 cc. The postcanines (the teeth behind the canines) were relatively large, and had more enamel compared to contemporary apes and humans, whereas the incisors and canines were relatively small, and there was little difference between the males' and females' canines compared to modern apes.[14]
Most scientists maintain that the genusHomo emerged in Africa within the australopithecines around two million years ago. However, there is no consensus on within which species:
Determining which species of australopithecine (if any) is ancestral to the genusHomo is a question that is a top priority for many paleoanthropologists, but one that will likely elude any conclusive answers for years to come. Nearly every possible species has been suggested as a likely candidate, but none are overwhelmingly convincing. Presently, it appears thatA. garhi has the potential to occupy this coveted place in paleoanthropology, but the lack of fossil evidence is a serious problem. Another problem presents itself in the fact that it has been very difficult to assess which hominid [now "hominin"] represents the first member of the genusHomo. Without knowing this, it is not possible to determine which species of australopithecine may have been ancestral toHomo.[14]
Marc Verhaegen has argued that an australopithecine species could have also been ancestral to the genusPan (i.e. chimpanzees).[19]
A minority view among palaeoanthropologists is that australopithecines moved outside Africa. One proponent of this theory isJens Lorenz Franzen, formerly Head of Paleoanthropology at the Research InstituteSenckenberg. Franzen argued thatrobust australopithecines had reached not only Indonesia, asMeganthropus, but also China:
In this way we arrive at the conclusion that the recognition of australopithecines in Asia would not confuse but could help to clarify the early evolution of hominids ["hominins"] on that continent. This concept would explain the scanty remains from Java and China as relic of an Asian offshoot of an early radiation ofAustralopithecus, which was followed much later by an [African] immigration ofHomo erectus, and finally became extinct after a period of coexistence.
— Jens Lorenz Franzen, "Asian australopithecines?",Hominid Evolution: Past, Present, and Future (1985)[20]
In 1957, an Early Pleistocene Chinese fossil tooth of unknown province was described as resemblingP. robustus. Three fossilized molars fromJianshi, China (Longgudong Cave) were later identified as belonging to anAustralopithecus species.[21] However further examination questioned this interpretation; Zhang (1984) argued the Jianshi teeth and unidentified tooth belong toH. erectus. Liuet al. (2010) also dispute the Jianshi–australopithecine link and argue the Jianshi molars fall within the range ofHomo erectus:[22]
No marked difference in dental crown shape is shown between the Jianshi hominin and other ChineseHomo erectus, and there is also no evidence in support of the Jianshi hominin's closeness toAustralopithecus.[22]
However,Wolpoff (1999) notes that in China "persistent claims of australopithecine or australopithecine-like remains continue".[23]
Media related toHominina at Wikimedia Commons| Taxonomy (Hominins) |
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