Australopithecines Tool Mfg

The Australopithecines

For classroom purposes only

Australopithecus anamensis


More chimp-like

Not as exciting as the others

Probably not a tool user

Australopithecus afarensis

Most well known hominid fossil

Primitive characters:

Small braincase (420 cc)

Relatively large, pointed canines

Bipedal, but with ape tendencies

Long arms, curved fingers, toes

Reconstruction of Australopithecine

Australopithecus

afarensis

Many Reconstructions

A recent find at the site of Lomekwi in Kenya has seen the addition of a new genus and species, Kenyanthropus platyops.

Leakey et al., 2001

Kenyanthropus

platyops

Kenyanthropus platyops

3.5 Ma

Kenya

Bipedal

Early Hominids

Late Miocene Early Pliocene hominins show transitional features

Relatively small brains

Relatively primitive dentition intermediate

Bipedal - probable arboreal behaviours

A. afarensis

Summary of Early Hominid Species

Species

Time Period

(million years B.P.) Distribution

Sahelanthropus tchadensis

Orrorin tugenensis

Ardipithecus ramidus kadabba

Ardipithecus ramidus


Australopithecus afaransis


Australopithecus bahrelghazalia

Australopithecus africanus

Australopithecus garhi

Paranthropus aethiopicus

Paranthropus biosei

Paranthropus robustus

Sometimes also called

Australopithecus

7-6

6.2-5.6

5.8-5.2

4.4

4.2-39.

3.9-3.0

3.5

3.5-3.0

3.5-2.5

2.5

2.5

2.3-1.4

1.9-1.0

Central Africa

East Africa

East Africa

East Africa

East Africa

East Africa

East Africa

North Central Africa

South Africa

East Africa

East Africa

East Africa

South Africa

Hominids as Erect Bipeds

The postcranial skeletons of Australopithecus and Paranthropus are those of erect bipeds.

Evidence includes the shape of the pelvis, the position of the foramen magnum, the presence of a lumbar

curve, the way the femurs are angled in, the anatomy

of the foot, and the Laetoli footprints.

Many hypothesis have been proposed to explain the advantages of erect bipedalism. These benefits include

raising the line of sight, freeing the hands, and assisting

the body in maintaining a proper body temperature.

Gracile vs. Robust

Body Types

Robust = full of strength, powerfully built, like Neanderthals

Gracile = graceful, slender, like Modern Humans

Gracile Australopithecines

Cranial Capacity - 450-530 cc

Fully Bipedal

Arises around 4 million years ago and lasts till around 1 million years ago

Two types Gracile and Robust

Begin making tools around 2.5 million years ago

Later

Australopithecines

At 3-2 myr hominins are

increasingly diverse

Paranthropus robusts

heavier build, larger toothed

A side branch, extinct by 1 myr

Australopithecus gracile

lighter build, smaller toothed

thought to be ancestral to Homo

The Early Hominids of South Africa

An early fossil find was a juvenile skull found at the Taung quarry and placed in the species Australopithecus africanus.

Fossils found in the Sterkfontein Valley belong to both Australopithecus africanus and Paranthropus robustus.

Australopithecus africanus Sts 5, from Sterkfontein, South Africa

Paranthropus robustus SK 48, from Swartkrans, South Africa

1985 David L. Brill 1985 David L. Brill

A clear biped foramen magnum

Australopithecus africanus

Teeth & mandible are human-like

Small canines

Large, flat molars

Australopithecus

africanus

The Early Hominids of East Africa

Olduvai Gorge in Tanzania, associated with the Leakey family, has been the site of finds of Paranthropus boisei and early members of the genus Homo.

West Lake Turkana was where Paranthropus aethiopicus was discovered.

Australopithecus anamensis was found at the site of Kanapoi in Kenya.

Hadar in northern Ethiopia was the site of the discovery of Lucy, who belongs to the species Australopithecus afarensis.

Fossilized footprints dating between 3.8 and 3.6 million B.P. have been found at the site of Laetoli.

Robust Australopithicines

(Paranthropus) Huge teeth and jaws

Huge muscles for these jaws with special crests to attach these muscles to.

Survived until around 1 million years ago

Slightly larger cranial capacity

The Paranthropus Skull

Paranthropus is characterized by specialized chewing apparatus that includes large premolars and molars associated with a thick,

deep mandible.

Many features of the skull are related to the development of powerful chewing muscles.

The zygomatic arch is long and powerfully built, flaring away from the skull.

A small sagittal crest appears on the top of most specimens for attachment of the powerful temporalis muscle.

Paranthropus

Lived from 2.5 to 1.2 myr

Differentiated from Australopithecus

Our close relatives

But not our direct ancestors

Went extinct by 1 myr!

Australopithecus aethiopicus

Anatomy reflects heavy muscular forces

Paranthropus

Characterised as megadontic

Large molars

Heavy, buttressed mandibles

Small anterior teeth

Australopithecus

boisei

Johanson & Edgar, 1996.

Paranthropus boisei OH5

Robust Hominids of East Africa

Australopithecus afarensis Top and side views of the mandible

LH 4 from Laetoli, Tanzania

Paranthropus aethiopicus WT 17000, the Black skull, from Lomekwi, West Lake Turkana, Kenya

Paranthropus boisei

OH 5, from Olduvai Gorge, Tanzania

1985 David L. Brill

Tim White

Alan Walker/National Museums of Kenya

Australopithecus robustus

Other Hominids

A recent find at the site of Lomekwi in Kenya has seen the

addition of a new genus and

species, Kenyanthropus platyops.

A find discovered in Chad, located in north central Africa, has been

placed in the species

Australopithecus bahrelghazalia.

National Museums of Kenya

Brain size is a critical criterion for assignment into Homo

Range in Brain Size

Australopithecines (400 to 545 cc)

Homo (509 to 1,880 cc)

Slight overlap between genera

Homo

Australopithecus

Hominin Brain Size

Australopithecines show a slight change through time

Homo shows a rapid increase

Homo shows substantial brain size increase over 2 myr

Early Hominid

Dentition In general, the dentition of

Australopithecus and

Paranthropus resembles that

of Homo. Yet early species

of Australopithecus show

many nonhominid features,

and Paranthropus evolved

rather specialized dentition.

For example, many features of the dentition of A.

afarensis are intermediate

between that of modern

humans and apes.

The dentition of Paranthropus is highly

specialized for heavy

grinding with the back teeth.

Tools and Dentition

Reduction in dentition

Lower chewing and grinding forces

Coincides with increasing evidence for tool use

Increasing dependence on culture

Early Hominid Tool Use

The earliest hominid tools were probably made of perishable tools such as wood, bark, leaves, and fiber. However, the evidence for tool use in the archaeological record consists primarily of stone objects.

The first concrete evidence of stone tool manufacture comes from a site in Ethiopia dated at 2.6 million B.P.

Further evidence for early hominid tool use stems from the anatomy of the hand. The hand anatomy of Paranthropus robustus introduced the possibility that members of this species were capable of a precision grip and complex toolmaking.

Chimpanzees are regular tool users with brain sizes avg. 370 cc

Brains and Tools

By 2 myr hominin brain sizes exceed the Great Apes

Hominins were

sufficiently

intelligent

to use tools

The Early Hominid Brain and Skull

The cranial capacities of Australopithecus and Paranthropus vary from 400 to 530 cubic centimeters, compared to an average of 1350 for modern humans.

The structure of the skull reflects a small cranium associated with large dentition and powerful chewing muscles.

The Australopithecus skull shows prognathism and the bones are pneumatized. The expansion of the temporalis muscle is reflected in the presence of a temporal-nuchal crest. The top views shows postorbital constriction.

The forehead, behind brow ridges, is low and flat.

Chimp Comparisons

Chimps show tool use

but do not equate with the Oldowan

Chimps create sites

but the density and nature of Oldowan sites is far different

Emergence of Tool Use

Earliest known tools are 2.5 myr old

Most occur from 2-1.5 myr

Oldowan Technology

Contemporary with early Homo

Lokalalei, Kenya

2.34 myr

Reassembly of stone tools

Shows a sequence of

flaking actions

Refit Stone Tools

Selected materials

knowledge of raw materials

Lokalalei, Kenya

Shows some forethought and knowledge of rock mechanics

Applied controlled flaking

required dextrous motor skills

Visibility of Tool Use

Behaviours become visible at 2.5 myr Witnessing an intensification of tool use

Oldowan Tools and

Sites

Oldowan Sites

Oldowan sites show diversity of types

Stone tool scatters Dense concentrations of stone tools

Stone tools with associated fossils

Site types imply different activities over the landscape

The Oldowan represents new adaptations and a dietary shift

Documents

Australopithecines Tool Mfg