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What are stable isotopes?
Forms of oxygen and carbon in different proportions depending on environmental conditions.
What is the extimated age of the earliest hominins?
What is the difference between the old view and the new view on the number of species?
- The Old View: Human evolution with relatively few species and fairly linear
- The New View: Human evolution extremely complicated & species-rich
What are the three Pre-Australopithecines?
- Sahelanthropus tchadensis
- Orrorin tugenensis
- Ardipithecus ramidus
Sahelanthropus tchadensis: how old are they and what are their defining characteristics?
- Dated - 7 mya
- Small Brain (<400 cm3)
- Massive browridges & cranial crests
- Small face & Anterior dentition
- Forward (inferior) foramen magnum (suggestive of bipedalism)
Orrorin tugenensis (“Millennium Man”): how old are they and what are their defining characteristics?
- Dated - 6 mya
- Very little cranial material but femurand other post-cranial fossils indicativeof habitual biped
- Ape-like teeth
Ardipithecus ramidus: how old are they and what are their defining characteristics?
- Dated - 4.4 mya
- Paleoecology: Woodland environment
- 40% Skeleton + pieces of 36 individuals
- Small brain (300-350 cm3) with relativelyunspecialized teeth and small canines
- Unique foot—bipedal adaptations & graspingbig toe
- Partially terrestrial, omnivorous/frugivorous
- Habitual biped:
- Forward (inferior) foramen magnum
- Arm not weight-bearing
- Pelvis and leg bones
- But lower pelvis with climbing adaptations
Australopithecus afarensis: how old are they?
Dated - 3.8-3 mya
What are the post-cranial features of Australopithecus afarensis?
- Habitual bipedalism
- Relatively long arms
- Retention of arboreal adaptations (curved phalanges)
What are the cranial features of Australopithecus afarensis?
- Small brain (350-500 cm3)
- Prognathic face
- Cranial crests
- U-shaped dental arcade
- Canine reduced but still large (with semi-sectorial lower 1st premolar)
Where were gracile and robust Australopithecines located?
- Gracile: South Africa
- Robust: South and East Africa
Australopithecus africanus: how old are they and what are their defining characteristics?
- Dated - 2-3 mya
- More derived:
- Small brain (450-500 cm3)
- Gracile skull
- Less prognathic face
What are the three types of Robust Australopithecines, and where were they located?
- A. robustus (South Africa)
- A. boisei (East Africa)
- A. aethiopicus (East Africa)
Robust Australopithecines: how old are they and what are their defining characteristics?
- Dated - 2.5-1 mya
- Small Brain (~500 cm3)
- Face, Jaws, & Teeth
What are the robust dietary adaptations?
- Sagittal Crest
- Large Jaw & Molars (Megadont)
- Broad Cheekbones
What we know about australopithecines?
- Habitual bipeds
- Small-bodied (3 ½ - 4 ½ ft. tall)
- Retention of arboreal adaptations
- Pronounced sexual dimorphism
- Unlikely monogamous
- Primarily vegetarian (Hunted nothunter)
- Limited tools & culture
- Limited population size & distribution