Australopithecus and Paranthropus Flashcards
Australopithecus anamensis - temporal range, sites, and environment
4.2-3.9mya
Kanapoi, Kenya
Allia Bay, Kenya
Asa Issie, Ethiopia
Aramis, Ethiopia
Open woodland/gallery forest environment, and open savannah environment
Australopithecus anamensis - derived traits compared to apes
Reduced canines
Larger molars, thick enamel
Undisputed bipedalism based on tibia - enlarged proximal extreme - earliest undisputed evidence
Australopithecus anamensis - primitive traits
More U-shaped dental arcade
Sloping mandibular symphysis
Premolar asymmetry
Australopithecus afarensis - temporal range, holotype and sites
3.7-2.8mya
LH4 (Laetoli)
Sites: Laetoli, Tanzania Omo, Ethiopia Hadar, Ethiopia Maka, Ethiopia Allia Bay, Kenya
Holotype
The single physical example of an organism used to formally describe the species
Hypodigm
All fossil materials that are recognised as part of a given species
Australopithecus afarensis - cranial traits
Large cheek bones Facial prognathism More vertical mandibular symphysis Reduced canines Thicker enamel Robust jaws Small brain size (380-430cc) relative to face Strong nuchal crest for muscle attachments Anteriorly placed foramen magnum
Australopithecus afarensis - dental changes
Incisors and canines become smaller
Postcanine dentition becomes relatively large
Enamel thickness increase from Au. anamensis
AL 288-1
“Lucy”
Australopithecus afarensis
3.2mya, Hadar, Ethiopia
Pattern of fractures found in her skeleton are compatible with a fall from considerable height, possibly a tree -> compressive and hinge (greenstick) fractures. This brings back the debate about whether Au. was still spending some time in the trees.
A.L. 333
Australopithecus afarensis
Hadar, Ethiopia
17 individuals - able to assess variation within the group.
Sexual dimorphism similar to orangutans or gorillas.
The Dikika baby
Australopithecus afarensis
3.3mya, Dikika region, Ethiopia
3 year old. Brain size and age suggests slower brain growth = derived trait from Pan
Semi-circular canals of the inner ear similar to apes
Curved fingers
Laetoli footprints
Australopithecus afarensis, 3.7mya
Discovered by Mary Leakey, 1978
Three sets of footprints - one in the steps of the larger - in a wet volcanic ash layer
Adducted big toe, development of arches, deep depression of the heel
Australopithecus afarensis - primitive/arboreal features
Phalanges long and curved for grasping and suspension
Glenoid cavity is cranially oriented
Long arms and short hindlimbs (large intermembral index)
Funnel-shaped thorax
Small lumbar vertebrae
Australopithecus afarensis - derived/bipedal traits
Low, broad ilium
Anteriorly rotated iliac blades
Lordotic curvature of lumbar vertebrae
Long femoral neck
Valgus knee
Large calcaneus
Anteriorly placed foramen magnum
Do primitive arboreal features necessarily reflect locomotion?
No - they may have just not disappeared yet
Australopithecus afarensis - environments
Au. afarensis lived in environments ranging from more closed woodland to dry open grasslands
The ability to walk AND climb trees would have allowed them to use resources from all of these environments
Australopithecus africanus - temporal range, holotype, and sites
3.2-2.4mya
Taung 1 cranium and mandible, Taung, South Africa
Sites: Taung, South Africa Sterkfontein, South Africa Makapansgat, South Africa Gladysvale, South Africa
Taung child
Australopithecus africanus
Small canines, human-like teeth
Foramen magnum on base of skull
Believed to have been killed by an eagle due to puncture marks at the bottom of the eye socket, as well as eggshells and an unusual mixture of animal bones found alongside the skull.
S.T.S. 5
Australopithecus africanus, female
Slightly enlarged brain and rounder cranial vault
Less prognathism compared to Au. afarensis
Less developed nuchal cresting
Reduced anterior dentition
S.T.S. 71
Australopithecus africanus, male
Cheek bones swept forwards, nasal pillars
Robust mandible
Larger cheek teeth with thick molar enamel
Australopithecus sediba - temporal range, holotype, sites
1.977mya
MH1 (Malapa, South Africa) - partial skeleton
Sites:
Malapa, South Africa
Australopithecus sediba - traits
Small brain and teeth Primitive-looking molars Derived thumb length Primitve curvature of phalanges Cranially oriented glenoid fossa Relatively long forearm
Au.-like in size but evidence for Homo-like reorganisation of brain structures
Australopithecus sediba - similarities with australopiths
Small brain size
Primitive molar cusps
Small body size
Long upper limbs
Australopithecus sediba - similarities with Homo
Front of brain reorganised
Smaller teeth and chewing muscles
Hand with precision grip
Paranthropus aethiopicus - temporal range, holotype and sites
~2.5mya
Omo mandible, Ethiopia
Sites:
Omo, Ethiopia
West Turkana, Kenya
KNM-WT 17000
“The Black Skull”
Transitional between Au. afarensis and P. boisei = P. aethiopicus?
Prognathic face
Moderately sized anterior tooth roots
In many craniodental features, not as robust as later P. boisei
Paranthropus aethiopicus - cranial traits
Well developed sagittal and nuchal crests
Prognathism
Relatively small brain
Forward-projecting zygomatics
Paranthropus boisei - temporal range, holotype, sites
2.3-1.4mya
OH 5 cranium, Olduvai, Tanzania
Sites: Olduvai, Tanzania Peninj, Tanzania Omo, Ethiopia Konso, Ethiopia Koobi Fora, Kenya West Turkana, Kenya
Paranthropus boisei - cranial traits
Forwardly-placed sagittal crest
Forward-projecting zygomatics
Prognathism
OH 5
“The Nutcracker Man” - although more recent analyses indicate otherwise
Paranthropus boisei, Olduvai, Tanzania, 1.8mya
Derived cranial features: Sagittal and nuchal crests Slight increase in brain size (~500cc) Large cheek bones Large posterior teeth Small anterior teeth Molarised premolars Large postcanine teeth
Australopithecus garhi
Ethiopia, 2.5mya Prognathic lower face Sagittal crest Cranial capacity 440cc Larger canines and incisors than paranthropus Large posterior teeth, but thin enamel
Possible P. aethiopicus variant
Paranthropus robustus - temporal range, holotype, sites
2.0-1.5mya using biochronology
TM 1517 cranium, Kromdraai, South Africa
Sites: Swartkrans Kromdraai Drimolen Gondolin
Paranthropus robustus and Paranthropus boisei shared traits
Sagittal crest
530cc
Dish shaped flat face
Small canine
Large postcanine teeth (larger in P. boisei)
Large and anteriorly placed zygomatic arches
GDA-2
The Gondolin molar
Paranthropus robustus (some researchers attribute it to P. boisei based on the large size and morphology)
Teeth/dental microwear and diet
Insectivory - sharp crests for puncturing the outer skeleton of insects
Frugivory - low cusps for crushing soft fruits
Folivory - well developed shearing crests for cutting tough leafy material into small pieces
Tough leaf eaters = lots of striations
Hard seed eaters = lots of pits
Carbon isotopes and diets
Plants use different photosynthetic pathways
C4 - grasses and sedges
C3 - most other plants
C4 and C3 have different C13/C12 ratios which get incorporated into animal tissues
Measure the ratio in bones and teeth to determine what a hominin ate
Issues with dietary isotopes
For carbon, does not necessarily distinguish between eating C3/C4 plants themselves or eating the animals that feed on the plants
R
Records diet when the tissues were formed e.g. human first molar = diet between 1-3 years
Phytoliths
Phytoliths in dental calculus and plaque suggest consumption of fruit, leaves, bark, C3 grasses and sedges.
Au. sediba - Diet different to contemporary hominins
Megadontia
All australopithecines have megadontia -> larger teeth for their body sizes than do either humans or other apes.
P. boisei has the largest teeth for its body size.
Cranial features of australopithecines
- Small brain size with massive and prognathic faces
- The premaxillary region is convex in both transverse and sagittal profile
- No deep groove behind the brow ridge
- Primitive cranial features e.g. low, sloping forehead, massive projecting face, prominent brow ridges
- Reduced canines, but diastema still identifiable in some Au. afarensis specimens
- Shape of the maxillary arcade is primitive, and tooth rows converge posteriorly (U-shaped)
Stone tool use
No stone tools have been found in direct association with Australopithecus
Hand morphology of Au. sediba suggests they may have had specialisation for precise handling needed for stone tool use - however they may not have used it.
Stone tools discovered in Lomekwi, Kenya, dated to 3.3mya, predate Homo. The identity of the first stone tool makers is unknown.
