1. Chapter 10 Early Hominins and Australopithecus

2. Becoming a Biped Anatomical Changes Constructing the Bipedal Body Plan
balancing the body’s weight over two limbs
Constructing the Bipedal Body Plan
Why Bipeds?

3. The Transition to Human Behavior
What Made Humans Human?
the anatomical shift from quadrupedalism came after a behavioral shift began
at every stage of the process, natural selection favored the form the evolving protohominin took
at the earliest stages of hominin evolution, brain size and intelligence were quite apelike

4. Will you Know a Hominin When You See One?
Bipedality
Dentition
Parabolic arch
Size of anterior and posterior teeth
Prognathism
CP3
Enamel
Cranial Features

5. The First Hominins Sahelanthropus tchadensis (7.0-6.0 MYA) Chad
Less prognathic face
Large brow-ridge
Smaller canines
Anterior foramen magnum
Small brain
U-shaped arcade
Thin enamel

6. The First Hominins (cont’d)
Orrorin Tugenensis (6.0 MYA)
Kenya
6 mya
Arm and femoral fragments may suggest bipedalism
Thick enamel
Small teeth
Large upper canines

7. The First Hominins (cont’d)
Ardipithecus ramidus (4.4 MYA) and Ardipithecus kadabba ( MYA)
ramidus
4.4 mya
Smaller canine
Anterior foramen magnum
Apelike molars
kadabba
mya
More apelike dentition
Originally considered a variant of ramidus

8. Australopithecus and Kin
Australopithecus anamensis ( MYA)
Thickened tibia
Primitive dentition
Lumped with afarensis?
Lived in forested region

9. Australopithecus and Kin (cont’d)
Australopithecus afarensis
mya
Lucy
Short, broad pelvis
Tilted femurs
In-line big toe
Sagittal crest
Small brain
Sexually dimorphic

10. Australopithecus and Kin (cont’d)
Australopithecus bahrelghazali ( MYA)
Western Africa
Mandible fragment with seven teeth
A specimen of afarensis?

11. Australopithecus and Kin (cont’d)
Kenyanthropus platyops (3.5 MYA)
Flat face
Small molar teeth
afarensis?

12. Australopithecus and Kin (cont’d)
Australopithecus garhi (2.5 MYA)
Small brain
Prognathic face
Large canines
Sagittal crest
More human-like postcranial proportions?
Tool use?

13. Australopithecus and Kin (cont’d)
Australopithecus africanus (3.5-<2.0 MYA)
Slight brain increase
Rounded vault
No crests
Less projecting face
Bipedal postcranial anatomy

14. Australopithecus and Kin (cont’d)
Australopithecus sediba ( MYA)
Discovered 2010 in South Africa
Slight brain increase ( cc)
Characteristics similar to Homo
dental anatomy
derived face
features of the pelvis

15. Australopithecus and Kin (cont’d)
'Robust' Australopithecus (or Paranthropus)
Hard object feeding
Sagittal crest
Large cheek teeth
Flared zygomatic arch
Dished face
Extreme postorbital construction
Woodland and open woodland habitat

16. Australopithecus and Kin (cont’d)
Robust Australopithecines (cont’d)
Australopithecus (p.) aethiopicus
mya
Australopithecus (p.) boisei
mya
Australopithecus (p.) robustus
mya