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Australopithecus africanus

Australopithecus africanus. Discovered: 1924 in Taung limestone quarry in South Africa by Raymond Dart Age range: 3.0 – 2.2 mya Type specimen: Taung Child (6 yo) Cranial capacity: 440 cc (avg.)

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Australopithecus africanus

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  1. Australopithecus africanus • Discovered: 1924 in Taung limestone quarry in South Africa by Raymond Dart • Age range: 3.0 – 2.2 mya • Type specimen: Taung Child (6 yo) • Cranial capacity: 440 cc (avg.) • Features: slightly projecting lower face, large molars, small front teeth & canines, short face

  2. Australopithecus africanus

  3. Australopithecus robustus • Discovered: 1936 by Robert Broom in South Africa • Age range: 1.8 -1 mya • Cranial capacity: 530 cc • Features: robust features = sagittal crest, large teeth, thick & wide cheekbones, large face, large jaw, small brain • Diet of hard food items: nuts, seeds, tubers, roots, leaves

  4. Australopithecus boisei • Discovered: 1959 by Mary Leakey in Tanzania (East Africa) • Note: Originally named “Zinjanthropusboisei” • Age range: 2.2 – 1.3 mya • Cranial capacity: 530 cc • Features: “Hyper-robust” – massive jaw, huge molars & big teeth w/wear, prominent sagittal crest • Cranial-dental features work as “grinding machine”; nicknamed “Nutcracker Man”; ate seeds, nuts, roots, tubers, leaves (NOT a tool maker---teeth are tools)

  5. Australopithecus afarensis (aka “Lucy”) • Discovered: 1974 in Hadar, East Africa by Don Johanson • Age range: 3.9 – 3 mya • Significance: • Antiquity - 1 my older than any other hominid found at that time • 40% complete – nearly all bones represented • Established bipedalism in earliest known hominid (w/small brain)

  6. Lucy’s Features • Only found in E. Africa • Cranial capacity – 375 – 550 cc. • Ape-like face • Low forehead • Bony ridge over eyes • Flat nose • No chin • Protruding jaws

  7. Lucy’s Features, Cont. • Large, thickly enameled back teeth • Slightly projecting upper canine • U-shaped jaw (like apes, but not identical) • 3 ½ - 5 ft. tall • Arms longer than legs • Pelvis & leg bones adapted for bipedalism • Curved finger & toe bones

  8. “The First Family” – A. afarensis • Discovered: 1975 by Don Johanson • Features: Remains of 13 individuals (male, female, adults, juveniles) • Highly sexually dimorphic (males much bigger than females) • Same features as Lucy • Significance: strong evidence of variation within the species & for A. afarensis as a hominid

  9. A. afarensis, cont. • The Laetoli Footprints • Discovered: 1978 in Tanzania by Mary Leakey • Age: 3.7 – 3.5 mya • Features: Prints reveal human-like stride; big toe in line with others; arch in foot • Significance: Establishes bipedality in earliest hominids

  10. Evolution of Bipedalism • Anatomical Adaptations • Australopithecines have wide, short pelvis • Femur is angled inward toward the knees to bear upper body weight • Modern human pelvis is rounded

  11. Early Hominid Bipedalism • Not EXACTLY like modern humans • A. afarensis ankle & shoulder joints more like a chimp’s (more flexibility) • A. afarensis finger and toe bones retain some curvature • Foramen magnum indicates A. afarensis is an obligate biped (committed to bipedalism) • Conclusion: A. afarensis spent time in trees & on the ground

  12. Comparison of Hominid Skeletons

  13. Adaptive Patterns of the Australopithecines • Bipedal • Small bodied (avg. height of 4-5 ft.) • Small brains (approx. same as modern chimp) • Tool use similar to modern chimps • NOT stone tool user • Small, social groups of bonded males/females & offspring

  14. The Australopithecines, Continued • Lived in mixed woodland/savannah • Foragers – gathered nuts, seeds, fruits, roots, tubers • Small populations • Genetic drift, mutations, selective pressures = rapid genetic divergence & eventual speciation • Represent a successful lifestyle

  15. Adaptive Patterns of Early African Hominids • Gracile australopiths • More omnivorous • More arboreal • Reflected in foot, ankle, • hand, wrist bones • A. afarensis, A. africanus

  16. Robust australopiths Diet of hard food items Less arboreal Due to food sources Extinct 1 mya A. robustus, A. boisei Different Genus? - Paranthropus Adaptive Patterns of Early African Hominids

  17. The Pre-Australopithecines

  18. Ardipithecus ramidus • Discovered: 1994 in Ethiopia by various research teams • Age range: 5.8- 4.4 mya • Features: most complete ancient hominid skeleton – bones of hand, feet, limbs, pelvis, most of skull & teeth; remains of males, females, juveniles

  19. A. ramidus, cont. • Mix of ape & human traits: • Small canines • Grasping big toe (only biped w/ this feature) • Long arms, short legs • Small brain • Hand bones NOT adapted for knuckle-walking • Small molars • Diet: omnivorious - plants, fruits, insects, nuts, seeds • Environment: lush woodlands, forests

  20. Ardipithecus ramidus • Significance: • 1 my older than Lucy • Closest established hominid to Last Common Ancestor with chimps • Evidence of bipedalism arising in a more arboreal context than previously thought

  21. Ardipithecusramidus, cont. Lucy (Au. afarensis) at left Ardi (Ard. ramidus) on right

  22. Ardipithecusramidus

  23. Orrorin tugenensis aka “Millenium Man” • Discovered: 2001 in western Kenya • Age range: 6 mya • Remains: Fragmentary arm & thigh bones; lower jaws & teeth • Features: Limb bones larger than later hominid species • Cranial capacity: Not yet determined • Notes: Some evidence of bipedality & tree climbing; dental & some skeletal features more human than ape like • Significance: More evidence that bipedalism may have originated in the trees

  24. Pre-Australopithecines, cont. Sahelanthropus tchadensis • Found in central Africa, country of Chad • Nearly complete cranium • Small braincase: 370-380 cc • Massively built, heavy browridges, crest in back, large muscle attachments • Reduced upper canine • Small, vertical face • Cannot determine bipedality • OLDEST possible hominid • Common ancestor?

  25. Other Australopithecines • You will not be tested on any of the following species, they are included here only to demonstrate the VARIATION present in early hominid evolution

  26. Australopithecus aethiopicus • Discovered: 1985 in Kenya • Age range: 2.8 – 2.2 mya • Cranial capacity: 410 cc • Features: Very broad projecting face • Large sagittal crest • Massive jaws and molars • Notes: Ancestor to A. boisei and A. robustus

  27. Australopithecus anamensis • Discovered: 1995 in Kenya by Meave Leakey • Age range: 4.2 – 3.9 mya • Remains: Skull, teeth, leg and arm bones • Cranial capacity: Not yet determined • Features: Thickly enameled teeth • Notes: Skull features are primitive • Body features are humanlike* • *Skull and skeletal bones may not be from the same species

  28. Australopithecus garhi • Discovered: 1999 in Ethiopia • Age range: 2.5 mya • Remains: 5 hominids; 1 partial skull, parts of limb skeleton • Cranial capacity: Not yet determined • Features: Extremely large back teeth, large front teeth, projecting face • Notes: Long forelimbs and long hindlimbs • Found in assoc. w/butchered animal bones • Could A. garhi be first stone tool user?

  29. Kenyanthropus platyops • Discovered: 2001 in Kenya by R. Leakey • Age range: 3.5 mya • Remains: Partial skull • Cranial capacity: 410 – 440 cc • Features: Large, flat face; small teeth • Notes: Some features foreshadow Homo

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