BIAN2013 Australopithecus africanus

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BIAN2013Australopithecus africanus
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Type specimen of Australopithecus africanus
The Taung Child From limeworks at Taung,
Northern Cape. Described in 1924 by Raymond
Dart A Queenslander. At 29, Professor of Anatomy
at Witwatersrand University, Johannesburg
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How old was the child at death?

• At this dental stage
• - a human child would be 6 years old
• a chimpanzee or gorilla would be 3 years
• Examination of enamel perikymata shows that it
  grew quickly, like a chimpanzee.
• It was about 3 years old.

M1 just in occlusion All other teeth are deciduous
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Dart was mostly ignored the Taung child was
just an ape
But a famous palaeontologist, Robert Broom (then
60 years old) agreed that Australopithecus was on
the human lineage, and determined to find adults.
He discovered adults at Sterkfontein (1936),
Kromdraai (1937), and Swartkrans (1947), and
showed that there were two or more species of
australopithecines, and that they really were
hominin
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Sts5Mrs Ples
1947 skull from Sterkfontein. Virtually complete
except for teeth. So-called because Broom thought
that the Sterkfontein fossils were a special
genus, Plesianthropus
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A.africanus differences from A.afarensis (Rak,
1983)
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Massive facial skeleton
Pan
Sts71
Stw505
Very large molars Enlarged masseters
A.africanus
Sts5
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Basicranium shorter than chimps, not as shortened
as humans
Homo
Pan
A.africanus
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Innominate bone
Mostly similar to human
Pan
European Homo Pygmy
But iliac blade lacks anteromedial twist
Sts14
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Häusler Schmid (1995) compared pelvis with from
Sterkfontein with that of Lucy , and maintained
that they differ as female does from male among
modern humans
Subpubic concavity U-shaped
Sts14
Subpubic angle 97
Protruding promontorium
Subpubic concavity V-shaped
AL 288
Less round inlet
Subpubic angle 80
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The second Sterkfontein pelvis
Stw431
Sts5
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Small head, long neck weightbearing
Australopithecine femora
Fairly short greater trochanter for glutei
Shallow trochanteric fossa for obturator externus
Fairly marked intertrochanteric line for
iliofemoral ligament
Small lesser trochanter for iliopsoas
Sts14
Stw431
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Makapansgat a third site for A.africanus
Discovered by Dart in 1947
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Breccia
The sites were filled with hardened, consolidated
soil, washed in through fissures along with
bones The breccia is harder than the bone
During the Pliocene, Sterkfontein and Makapansgat
were probably lairs of large carnivores. The
Taung child was the prey of an eagle.
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Ron Clark demonstrating the stratigraphy of
Sterkfontein
Member 5 Early Pleistocene Contains Homo and
stone tools
Member 4 Australopithecines
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How old are Sterkfontein, Taung and Makapansgat?

• Faunal analysis suggests Sterkfontein Member 4 is
  about 2.5 Ma, Taung younger, Makapansgat nearly 3
  Ma
• ESR dating puts Member 4 at about 2.4 Ma, Member
  2 about 1.8 Ma
• New dates for Member 2 are 4.02 Ma (Jacovec
  Cavern) and 4.17 Ma (Littlefoot breccia), by
  Be10 and Al26 decay.

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Littlefoot(Stw573)
Foot bones discovered in the 1980s, thought to be
from a monkey, laid aside for further study. In
1995, Ron Clarke examined them, concluded they
were hominin. Clarke Tobias (1996) described
them as representing a biped with an unusually
divergent hallux. In 1997, Clarke identified more
tarsal and leg bones. He noticed the clean break
at the ends of the tibia and fibula, and the
similarity of adhering breccia to that of the
Silberberg Grotto (Member 2). He began a search
of the grotto.
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In 1998, the site was found. Sufficient was
exposed to indicate that the complete skeleton
was present.
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The emerging skeleton
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New fossils from the Jacovec Cavern
Superior temporal line approaches top of
calvaria Deep postorbital constriction EAM
chimpanzee-like
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Homage to Robert Broom
Monument to Broom at Sterkfontein
Where most of the fossils are kept the Broom
Room in the Transvaal Museum