Early Hominins Slides

Report
Genus Homo
Archaic
Primitive

Modern human characteristics
› Appeared at different times
› Evolved at different rates

Extinct hominids show a mosaic of
derived and ancestral characteristics

Locomotion
› Shift from inefficient to more efficient bipedality ca. 2 mya

Dentition
› Enamel thickening ca. 4 mya
› Gradual reduction of anterior dentition 4.5 mya to present
› Gradual reduction of posterior dentition ca. 2.5 mya to
present

Encephalization
› Limited encephalization from 4 mya to 2.5 mya
› Marked encephalization from 2.5 mya to ca. 150 kya

Pelvis

Distribution of body
mass

Relative limb-length

Position of foramen
magnum

Lumbar vertebrae

Foot
Age – estimated to be between 6 and 7
mya
 Fossil remains

› Nearly complete cranium
› Several fragmentary mandibles
› Isolated teeth
Cranial capacity – 320-380 cc
 Classification uncertain – several possibilities
 Position of foramen magnum suggests nonbipedal

Chimp-sized brain
 Hominin-like brow
ridges
 Canine wear
pattern not apelike
 Thick hominin-like
mandible

Age ca. 6mya
 Fossils remains – mandibles, femur,
humerus, large molars, small canines

› Femur suggests bipedality
› Humerus suggests tree-climbing skills (but not
brachiation)
› Long bones suggest chimpanzee size
› Teeth resemble later hominids
“Gracile”
(afarensis)
“Robust”
(aethiopicus)
24

STS 5

Au. africanus

P. boisei

Age ca. 2.5 mya
› Later Australopithecine
Limbs suggest bipedality
 Incipient megadontia


Found with stone tools and butchered
animal remains

similar documents