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 Praeanthropus. The term comes from a former classification as members of a distinct subfamily, the Australopithecinae. They are now classified within the Australopithecina subtribe of the Hominini tribe. All these related species are now sometimes collectively termed australopithecines, australopiths or homininans. They are the extinct, close relatives of modern humans and, together with the extant genus Homo, comprise the human clade. Members of the human clade, i.e. the Hominini after the split from the chimpanzees, are now called Hominina[1] (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 genera Kenyanthropus, Paranthropus and Homo probably emerged as sister of a late Australopithecus species such as A. africanus and/or A. sediba.
The terms australopithecines, et. al., come from a former classification as members of a distinct subfamily, the Australopithecinae. Members of Australopithecus are sometimes referred to as the "gracile australopithecines", while Paranthropus are called the "robust australopithecines".[2]
The australopithecines occurred in the Late Miocene sub-epoch and were bipedal, and they were dentally similar to humans, but with a brain size not much larger than that of modern non-human apes, with lesser encephalization than in the genus Homo. Humans (genus Homo) may have descended from australopithecine ancestors and the genera Ardipithecus, Orrorin, Sahelanthropus, and Graecopithecus are the possible ancestors of the australopithecines.
Classification of subtribe Australopithecina according to .
Phylogeny of Hominina/Australopithecina according to Dembo et al. (2016).[3]
The post-cranial remains of australopithecines show they were adapted to bipedal locomotion, but did not walk identically to humans. They had a forearm to upper arm ratio similar to the Golden Ratio[4] [5] – greater than other hominins. They exhibited greater sexual dimorphism than members of Homo or Pan but less so than Gorilla or Pongo. It is thought that they averaged heights of 1.2m–1.5mm (03.9feet–04.9feetm) and weighed between 30kgand55kgkg (70lband121lbkg). The brain 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.
Most scientists maintain that the genus Homo emerged in Africa within the australopithecines around two million years ago. However, there is no consensus on within which species:
Marc Verhaegen has argued that an australopithecine species could have also been ancestral to the genus Pan (i.e. chimpanzees).[6]
See also: Meganthropus. A minority-held view among palaeoanthropologists is that australopithecines moved outside Africa. A notable proponent of this theory is Jens Lorenz Franzen, formerly Head of Paleoanthropology at the Research Institute Senckenberg. Franzen argues that robust australopithecines had reached not only Indonesia, as Meganthropus, but also China:
In 1957, an Early Pleistocene Chinese fossil tooth of unknown province was described as resembling P. robustus. Three fossilized molars from Jianshi, China (Longgudong Cave) were later identified as belonging to an Australopithecus species. However further examination questioned this interpretation; Zhang (1984) argued the Jianshi teeth and unidentified tooth belong to H. erectus. Liu et al. (2010) also dispute the Jianshi–australopithecine link and argue the Jianshi molars fall within the range of Homo erectus:
However, Wolpoff (1999) notes that in China "persistent claims of australopithecine or australopithecine-like remains continue".