Australopiths Flashcards
Australopiths - two types
gracile = Australopithecus
robust = Paranthropus
major trends in Australopiths
- dentition: reduced size, larger cheek teeth, thicker enamel
–> Paranthropus: chewing adaptation, postcanine megadontia - locomotion/posture - adapatations for bipedalism
- relative brain size, not that much larger compared to apes
- body size: smaller than modern humans w/ more sexual dimorph.
- ~3-4 ft tall
Australopithecus Discovery
1920s, Raymond Dart
- not accepted b/c of Piltdown Hoax (‘12-‘52)
A. afarensis
L: East Africa
T: 3.9 - 2.9 mya
A. afarensis findings
“Lucy” - one of the first full skeletons - 3.2 ma
Dikkia, Ethiopia –> recently
- 3.3 mya
- approx. 3 yrs old
A. afarensis skull (4)
- sagittal crest
- small brain size
- strong nuchal crest
- relatively prognathic
A. afarensis dentition (5)
UJ
- canine further reduced
- posterior tooth rows parallel
LW
- thicker molar enamel (frugivorous & hard seeds)
- slightly larger cheek teeth
- lower 3rd premolar usually bicuspid
A. afarensis skeleton (7)
- FM forwardly placed
- lumbar curvature
- short, broad pelvis, curved illium
- valgus knee
- enlarged heel, arches, non-opp. big toe + short toes
- significant sexual dimorph (in gorilla range)
A. afarensis arboreal features (3)
- relatively long, curved hand bones
- mobile, upward facing shoulder joints
- rel. long upper limbs vs lower limbs
Laetoli findings - A. afarensis
- biped in footprint fossils
- adducted big toe
- dev. of arches
- deep depression of heel
Diverse Habitats - A. afarensis
-closed woodland to dry, open grasslands
- ability to walk & climb trees = all the resources
Early Australopithecus fossil sites
Ethiopia, Kenya, Tanzania, Chad
A. africanus
L: South Africa
T: 3.5 mya - 2 mya
A. africanus female traits (4)
compared to afarensis
- slightly enlarged brain & cranial vault
- less prognathism
- less developed nuchal crest
- redacted anterior dentition
A. africanus male traits (4)
think about Manny
- cheek bones swept forward
- nasal pillars
- robust mandible
- larger cheek teeth w/ thicker molar enamel
A. sediba
L: South Africa
T: 2 mya
A. sediba - similarities w/ Aus.
- small brain size
- molar morphology
- small body size
- long upper limbs
A. sediba - similarities w/ Homo
- projecting nose
- smaller teeth & chewing muscles
- hand w/ precision grip
- longer legs
Paranthropus - major evolutionary trends @ 2.5 mya
hyper-masticatory complex
increase in cheek tooth size
- thick molar enamel
- increase frontal dental reduction & crowding
similar body size to Aus.
P. aethiopicis
L: East Africa
T: 2.7 - 2.4 mya
P. aethiopicis characteristics
- well developed sagittal & nuchal crests
- prognathism & dish-shaped face
- relatively small brain
- forward zygomatic
P. boisei
L: East Africa
T: 2.3 - 1.2 mya
P. boisei characteristics (4.4)
- forwardly placed sag. crest
- reduced prognathism
- forward zygomatic
- dental
a. front crowding
b. reduction in incisors/canines
c. thick enamel
d. increase in pre/molars
P. robustus
L: South Africa
T: 2 - 1.5 mya
P. robustus characteristics
- ate tough foods, esp. during scarcity
^^ P. boisei as well
