1. 8 mya: fossil apes 3.5 mya: Australopithecus afarensis Cimpanzee-human divergence estimated from genetic data at around 5 mya. Gap in fossil record when this hypothetical divergence occurred. Looking for hominids with bipedality and a non- honing chewing complex. Then, fossils from the critical time-gap were discovered—the pre-australopithecines.

2. Hominid traits: non-honing chewing; bipedalism

3. Rocky Mountain News - July 11, 2002

4. Sahelanthropus tchadensis Brain: 350 cc Massive brow ridge Foramen magnum forward Nonhoning complex 6-7 mya

5. The habitat: woodland

6. Orrorin tugenensis c. 6 mya Bones of 5 individuals A finger bone, curved: ancestral characteristic (arboreal) The habitat: woodland Femur Evidence of bipedalism

7. And then! Ardipithecus kadabba (Early): 5.8—5.5 mya Ardipithecus ramidus (Late): 4.4 mya Probably anagenesis Significance: time of existence On the human lineage just after the chimpanzee-human split. Early: CP 3 honing complex like chimpanzee Late: honing complex gone Chimpanzee and Ar. kadabba

8. Science October 2009 Dedicated to 11 papers on A. ramidus

9. Bones from a sedimentary rock stratum c. 3 m thick (100-10,000 time range) Sandwiched between two layers of tuff Laser fusion 39 Ar  40 Ar dates of 4.4 my

10. Estimates 4 ft. tall 110 lbs. ♀ Last common ancestor of chimpanzees and humans was not chimpanzee-like palmigrade clambering + rudimentary bipedalism

11. Opposable big toe (ape like) But foot lacks flexibility Foot

13. Three groups that disappeared

14. Australopithecus aethiopicus Temporal fossa Sagittal crest Zygomatic arch

15. boisei robustus boisei aethiopicus

16. Australopithecus africanus Australopithecus robustus + Au. boisei Teeth: surface patterns

17. Important hominins aethiopicus afarensis boisei africanus robustusHomo habilis

18. Australopithecines Australopithecus anamensis (4.2 mya) –basal to other australopithecines) –definitive evidence of bipedalism Considered to be in the human lineage.

20. Australopithecus afarensis “Lucy” (Hadar, Ethiopia)

21. 3 year old child Australopithecus afarensis 3.6-3.0 mya Adult

22. 3.6 mya Australopithecus afarensis? Why?

23. Large toe in line with the other toes Hominid foot characteristic

25. Australopithecus garhi 2.5 mya