Homo-like features in australopiths: primitive?
In imitation of Dart, Broom & Le Gros Clark, the australopith spp are now usu.considered to be closer relatives of humans than of apes. This opinion is based esp. on their locomotor & dental features.

Ventral position of foramen magnum
It is generally accepted that the australopiths were more BP than present-day gorillas & common chimps, mostly because of the Laetoli footprints almost 4 Ma, the short ilia of Lucy & Sts.14, the broader calcaneus & the more human-like orientations (
though rather ape-like anatomy) of the ankle & knee articulations of the Hadar spms (Stern & Susman 1983, Latimer cs 1987) & the more ventral position of the for.magnum in many australopiths. “Early australopiths are linked with living humans on
the basis of shared characters related to BPism” (Andrews 1992), but it is often argued that the African apes’ ancestors also were more BP (theory of WL Straus, see Coon 1954, Kleindienst 1975, Goodman 1982, Gribbin & Cherfas 1983, Hasegawa cs 1985,
Edelstein 1987, cf. Schultz 1949:205). Indeed, that the African apes could evolve from digiti-palmigrades (all other primates + human infants) to knuckle-walkers implies that they went through a phase where the arms were barely used for pronograde
locomotion (cf. Edelstein 1987); an intermediate phase of orthograde arm-hanging or brachiation insufficiently explains KWing: neither orangs nor hylobatids show traces of KWking. Also, most anthropoids (esp.the young) occasionally walk on 2 legs, and
BP tendencies are very striking in the African apes (but almost absent in Pongo). Chimpanzee fetuses shortly before birth show more human-like feet with ventrally oriented & adducted first digital rays (Coon 1954). Common chimps often walk bipedally on
muddy terrain (Nishida 1980), bonobos are even more frequently BP (Zihlman cs 1978, De Waal 1988). “When they are on the ground, anthropoid apes... often walk erect, and the mountain gorilla's foot, indeed, is already similar to man’s” (Rensch 1972:
63,130, Schultz 1950, Edelstein 1987). Of all primates, only the African hominoids are fully plantigrade (Gebo 1992):
“Orangutans have further enhanced foot mobility by adapting their feet for suspension and thus similarly utilize foot positions where the heel does not touch the substrate. Chimpanzees & gorillas represent an alternative pattern (plantigrady), in which
the heel contacts the surface of the support at the end of the swing phase, esp. during terrestrial locomotion. Thus chimps & gorillas possess feet adapted for both arboreal & terrestrial substrates. African apes also share several osteological features
related to plantigrady & terrestrial locomotion with early hominids. Humans & African apes are very similar in their use of plantigrady when moving or standing upon a terrestrial substrate - this pattern of foot use is extremely different from what
characterizes all other primates”.
Also, young gorillas & chimps have foramina magna more ventral than adults, well within the range of A.africanus Sts.5 (Ashton & Zuckerman 1952, Schultz 1955). Even in adults, the foramen has the same position indices in gracile (Sts.5) & robust
australopiths (ER 406) as in bonobos (Kimbel cs 1984, table 9). Masters cs (1991):
“Since Taung was perhaps 3.5 yrs of age at death (Bromage & Dean 1985), the position of the for.magnum may not have achieved its adult status. This contradicts the assessment made by Dart (1925), who interpreted the position of the for.magnum as
indicating BP locomotion in Australop.africanus”. (Hum.Evol.9:121-139, already 1994).
... chimp & gorilla KWing has been argued to have arisen independently (Begun 1992), possibly in more BP ancestors (Kleindienst 1975, Hasegawa cs 1985, Edelstein 1987): Gorilla KWing anatomy & ontogeny are much better developed than in Pan, and different
from Pan (Inouye 1992). And the LCA (Homo-Pan last common ancestor) had not yet acquired KWing: humans do not at any age show the slightest trace of KWing behaviour:
1) we lean (e.g. on a table) far more comfortably on our proximal than on our middle hand phalanges,
2) in KWing apes, the middle hand phalanges are naked, but in many men they are dorsally haired - fingers III & IV (that bear most weight in KWers) even more frequently than V & II (Harrison 1958, Singh 1982, Ikoma 1986),
3) “human infants walk or run spontaneously on all 4s, and this invariably with the palms flat on the ground, the fingers completely extended” (Schultz 1936:264).
Lucy’s arms were much shorter than a bonobo's (humerus 24 cm vs 29 cm, cf.human pygmies 26 cm) and lacked KWing adaptations (Jungers 1982, Stern & Susman 1982), but later the small hominid O.H.62 had more chimp- & bonobo-like proportions (Korey 1990,
Aiello & Dean 1990:258, Wood 1992), and the larger KNM-ER-1500 (boisei female?) showed some gorilla-like proportions, e.g. rel.large forelimbs (McHenry 1978, 1992). The early KNM-KP 271 distal humerus was “similar to that of modern man” (Senut 1980,
cf.Oxnard 1984 & Aiello & Dean 1990:365-8), but A.robustus TM-1517 was more chimp-like, and A.boisei KNM-ER 739 more gorilla-like (Senut 1980, Aiello & Dean 1990:365-8). Body weight estimations for robustus and boisei based on formulae for ape
postcrania fit much better with the massive jaws than estimations based on human formulae (McHenry 1991). The boisei ulnae O.H.36 & L.40-19 & humerus KNM-ER 739 were of gorilla robusticity & length (McHenry 1991,1992, Howell & Wood 1974, Senut 1980,
Leakey 1971, Aiello & Dean 1990-367-9), and the curvature & the cross-section of L.40-19 are reminiscent of KWers (Howell & Wood 1974); “the Rudolf australopiths may have been close to the KWer condition, not unlike the extant African apes” (Leakey
1971). Their arm lengthening & strengthening is paralleled ontogenetically in the African apes. Rensch (1972:45) even states: “it is only after birth that an ape’s arms become disproportionally long”, but this can only be true when arm growth
relative to the height in African apes is compared with monkeys (Schultz 1936).

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