7 - early human evolution Flashcards
australopith species and dates
austolopithecus anamnesis 4.2 - 3.9 mya
afarensis 3.9-2.9 mya
deyiremeda 3.5-3.0 mya
bahrelghazeli 3.5-2.0 mya
africanus 3.5-2.0 mya
garhi 2.5 mya
sediba 1.9 mya
When was the first australopith discovered
- 1924 in South Africa - found by quarry workers and studied by Raymond Dart
- informally ‘tuang child’
- Australopithecus africanus -
- forwardly placed foramen magnum, no projecting diastema
Second found australopith
1947 - Sterkfontein, south africa
STS 5 - ‘Mrs Ples’ 2.5 mya
clearly bipedal
Australopithecus anamensis
- 1st found 1995 - Maeve Leakey - Lake Turkana, East Africa
- teeth more primitive than later hominids (larger canines, dental arcade u shape)
- tibia thickened at both ends as a result of weight bearing in bipeds lower limb
- arm bones still adapted for life in trees
First Australopithecus afarensis found
1974 - Donald Johanson - Hadar (ethiopia)
“Lucy” - AL288-1
40% complete skeleton
just over 1m tall
brain size like an adult chimp ( c 400 cc)
bipedal before brain expansion
anatomy mosaic of human and ape like features
crania and postcrania of Australopithecus afarensis
CRANIA
- cranial capacity small c 415cc
face prognathic
dental arcade u shaped with large front teeth (like ape)
POSTCRANIA
- thorax funnel shaped, possibly due to large gut from vegetal diet)
- arms longer relative to leg length
- strongly muscled shoulders
- curved phalanges on hand and feet
A. afarensis - Biped
POSTCRANIAL BIPEDAL ADAPTATIONS
- Pelvis - short iliac blades curved around side
- femur angled towards knee
- tibia modified to bear more weight
EXAMPLE
- Laetoli footprints, Tanzania 3.5 mya
- trackway of a.afarensis individuals
- show longitudinal arch
- big tow in line with others
Kenyanthropus Platyops
3.5 - 3.3 mya
- robust face: deep and flat face and strong cheek bones
- small cheek teeth
- but constructed of many tiny fragments - maybe just Australopithecus afarensis
Australopithecus deyiremeda location
Ethiopia, near Hadar site (Australopithecus afarensis) - more than one homini species same time and place
australopithecus deyiremeda maxilla and mandible
teeth smaller than Australopithecus afarensis, mandible more robust, different diets? niche partitioning?
Spoor, F (2015) Nature
Australopithecus africanus location
South Africa e.g. sterkfontein, makapansgat, swartkrans
A. africanus cranium
- larger brain case ( 450-550cc) than afarensis, and more rounded vault. less prognathic
dentition:
- incisors and canines smaller than afarensis but molars larger.
-shidt from slicing to crushing/grinding
A. africanus postcrania
very similar to a.afarensis, still adaptation for arboreal behaviour.
e.g. STS14 - 2.5 mya - found 1947 - Robert Broom
-outward flare of iliac blades (like afarensis)
-lumber curve in back
- 6 lumbar vertebrae (5 in modern humans)
australopithecus garhi
- 1999, Bouri, Ethiopia
one partial skull with large teeth - small brain (c450cc) + prognathic face
- post cranial material nearby - same species? (long femur like humans and long arms like apes) (found with tools and evidence of large mammal butchery)
- ancestral to homo?
australopithecus sediba
2008, Malapa in South Africa
(2 partial skeletons - one juvenile, one adult)
- habitually bipedal
- descended from africanus
- ancestral to homo?
autralopith characteristics and homo characteristics on autralopithecus sediba
Australopithecus characteristics
- small cranial capacity c400cc
- small body size
- long arms
Homo characteristics
- features of pelvis
- teeth similar size to homo
small post canine dentition
Robust australopithecines / Paranthropine species
Genus : Asutralopithecus
Species:
aethiopicus 2.7 - 2.5 mya
boisei 2.3 - 1.2 mya
robustus 2.0 - 1.5 mya
gracile vs robust
changes in skull morphology not body build
Paranthropus: crania and teeth
share chewing specialisations
- massive jaws
- huge crushing/grinding teeth
- sagittal crests
- adaptations to chewing tooth food items e.g nuts and seeds
- produce large bite forces - chewing muscles maximised in size and placement
Paranthropus aethiopicus ‘the black skull’
East Africa - Lake Turkana, Kenya - 1985
- Huge molars and large anterior teeth
- very prognathic dished face, flared zygomatics
- small brain c400cc
- prominent sagittal crest
Earlier than P.boisei and P.robustus but only shares distinctive features with P. Boisei (ancestral?)
Paranthropus boisei
East Africa - Ethiopia, Kenya and Tanzania
- cheek teeth massive, front teeth small and crowded
- brain 500cc
- face plate and deep - facial buttressing
- flaring cheekbones
P.boisei example
OH5 - “Zinj”
- Mary and Louis Leakey
- 1.8 mya
- massive skull, broad concave face
- molars x4 modern
Paranthropus robustus
South African - Komdraai and Swartkrans
- brain size c500-550cc
- heavily built face and jaws
- small anterior teeth
how does P.robustus differ from P.boisei
- massive cheek teeth but not as big as P.boisei
- shape of nasals
- bow ridge
- presence of bony pillars next to the nose
