6 - intro to paleoanthropology Flashcards
hominids
collective name for modern and fossil species of humans
hominid African ape lineage split
6-8 million years ago, likely in east Africa
evidence:
- comparative anatomy
- fossil evidence
- genetic evidence
what two parts is the skull made up of
cranium and mandible
cranial bones
frontal
maxilla
zygomatic x2
sphenoid
parietal x2
temporal x2
occipital
axial skeleton
vertebrae, sternum, ribs
upper limbs
clavicle, scapula, humerus, radius, ulma
lower limbs
pelvis, femur, tibia and fibula
hand and feet
phalanges, metacarpals, metatarsals, carpals, tarsals
hominins characteristics
bipedalism, large brain for body size, advanced dentition with rotary chewing
bipedalism
- primary mode of locomotion only in humans and our ancestors.
- human primates use a striding gait where weight is alternatively placed on a single full extended hind limb
- non humans walk bipedal with hips and knees bent
formamen magnum bipedalism adaptations
- situation towards back of cranium in non human apes
- repositioned underneath cranium in humans
- head is balanced on spine
- requires less robust neck muscles to hold head upright
spine bipedalism adaptations
- assists balance when we walk upright
-quadrupedal primate spine has a ‘c’ curve, humans have ‘s’ to absorb shock as we walk - weight transmitted down through body centre
pelvis adaptations to bipedalism
- quadrupedal animal - pelvis bones elongated and positioned along each side of the lower portion of spine
- humans - pelvis shorter and broader and extends around to the side
hind limbs bipedalism adaptations
- lower limbs elongated proportional to thighs
-femur angled inward to keep legs directly under body - modified knee anatomy so leg held straight and locks at knee
feet adaptations to bipedalism
- non human ate feet used as a grasping limb
- hallux (big toe) enlarged and non divergent
- longitudinal arch in foot absorbs shock and adds propulsive spring
- “toe-off” walking
some genera of early hominins
sahelanthropus, orrorin, ardipithecus, paranthropus, australopithecus, homo
how to recognise a fossil hominin when its lots of small parts
- evidence of bipedalism
- teeth (smaller canines)
- thickness of enamel (thin in living African apes, thicker in humans)
- decrease in facial size
earliest possible hominins
- orrrorin tugenensis
- sahelanthropus tchadensis
- ardipithecus ramidus
(NOTE: hominid status of orrorin and sahelanthropus debated)
sahelanthropus tchadensis
2001 - Chad
6-7 mya
- only cranium and dentition:
- forward positioning of foramen magnum
- brain c 320 - 380cc
- very large supra-orbital torus
origin tugenensis
tugen hills, Kenya, 2000
c 6.0 mya
- Bipedal:
- attachment on femoral neck
- no cranium
- partial mandible
ardipithecus ramidus “ardi”
1994 - Aramis, Ethiopia
c 4.4 mya
Mosaic of ape and incipient hominid features:
- forward position of foramen magnum
- long muscled arms
- no knuckle walking features
- opposable big toe
- brain c300-350cc
ardipithecus cranium
- cranium found in 5000 pieces
- brain c300-500cc
- small face with projecting muzzle (like apes but less projecting than chimps)
ardipithecus pelvis
mosaic of characteristics for bipedality and climbing
- short iliac blades like hominins
- lower pelvis more non-human ape like due to large thigh muscles for climbing
ardipithecus feet
- opposable big toe but different from extant great apes
- feet unlike extant apes
- has an os peroneum - used to draw in big toe when foot is grasping (found in gibbons but not extant great apes)
