ANT Quiz 5

Sahelanthropus Tchadensis

Sahelanthropus Tchadensis

• Chad

• 7 - 6 mya

• Bipedal

• Massive brow ridge

Orrorin tugenensis

• Kenya - woodlands and savannah

• 6 mya

• thick dental enamel

Ardipithecus ramidus

• Found in Ethiopia - close canopy forest

• 5.8 - 5.2 mya

• Divergent big toe

A. Anamensis

(4.2 - 3.8 mya)

A. Anamensis

• Kanapo and Allia Bay, Kenya

• Ethiopia

• Dry woodlands riverine gallery forests, open grasslands

A. Anamensis

• Thick enamel

• Powerful arms (arboreal)

• Large, broad molars

• U- shaped dental arcade

• Bipedal

A. Afarensis

(3.85 - 2.95 mya)

A. Afarensis

• Hadar, Ethiopia - Lucy! (showed us evidence of bipedalism)

• Laetoli, Tanzania

• 300 individuals

• Variable environments = Woodland to savannah

A. Afarensis

• ~ 450 cc

• prognathic/nuchal crest

• Intermediate dentition

• Dental arcade v-shaped

• Diastema

• Medium canines

• Bicuspid premolar

• “Males” 100 lbs/ “Females” 65 lbs

lucy's child

• Leg bones suggest bipedality

• Hyoid bone like apes

• Finger bones long and curved

• “all purpose” shoulder - scapula like gorillas

A. Africanus

(3 - 2.2 mya)

A. Africanus

• South africa

• taung /sterkfontein

A. Africanus

• ~ 440 cc

• Post crania similar to A.afarensis

• Shorter face

• Smaller,less dimorphic canines

• Base of skull bent upwards “flexed”

• Large molars, big jaw

A. Sediba

showed us there is many forms of bipedalism and bipedalism evolved differently

Australopithecus

• 6 species know

• Ape-like prognathic face

• Adapted to generalized diet

• Fast development

Paranthropus

• 3 species know

• Ape-like prognathic face

• Adapted to diet of hard items

Kenyanthropus

• Flat face

• Small teeth

The Australopithecines shared certain key adaptations

• Bipedal

• Still adept in trees

• Small bodies

• Teeth, jaws, skull intermediate between apes and later hominids

• Ape-like development patterns

• wean/grow up fast

• Ape-sized brains

• Pronounced sexual dimorphism

• woodland/scrub/grassland habitat

H1

efficient way to travel on ground for apes

cost of locomotion

• Effective mechanical advantage

• Limb length - length of limbs

• Length of muscle fibers

Effective mechanical advantage

the ratio of external ground reaction force moment arm to interval muscle-tendon moment arm

humans cost of locomotion

• Shape of pelvis directly impacts EMA

• Humans have arches in their feet that gives up spring

• Shorter straighter toes, shorter feet

H2

Good way to keep cool in open country

H3

leaves hands free for carrying things (food, infants)

H4

efficient for harvesting food from small trees

H5

adaptation for locomotion on flexible branches

H5

possible that energy efficiency was not the original selective pressure

Conical thorax

• Individctive of a large gut

• Obstacle to arm swinging while running

emergence hypothesis

the rise of collective behaviors, bipedalism

Paranthropines

Bipedal apes with very big molars

Parathropus boisei

nutcracker man who ate grass

herbivores

take up calcium > strontium = Sr/Ca ratio is low

carnivores

take up calcium >> strontium = Sr/Ca ratio is very low

C3

preferentially take in 13C over 12C

C3

• lower delta C13 value

• Trees, shrubs, some herbs, and animals that eat those things

C4

• higher delta c13 value

• Tropical grasses, sedges, and animals that eat those things

Robust dental features

seen in all three Parathropines are adaptations to a similar, and very specialized, dietary niche

400-500 cc

Australopithecus brain size

Megadontia quotients

reveal evolutionary trends in tooth size among hominids

Paranthropus boisei

C4 plants, limited variety

Paranthropus robustus

c3, looks of variety