Bones W8
February 28 , 2017
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Bipedalism and What Is a Hominin?
How can you identify an animal being Bipedal?
-Position of Foramen Magnum
-Rib Cage (barrel-shaped)
-Vertebral Column, in humans we see more curvature of the spine, Lordosis
-Pelvis Shape, Iliac blades are shorter and wider in humans, “Basin-shaped” pelvis supports abdominal organs
-Center of Gravity, ours is over our hips, less energy resting tendency to fall forward
-Limb Proportions, our legs are longer than our arms, efficient bipedal stride
-Valgus Knee
-Arch in foot
-Convergent Big Toe
-Pedal phalanges (toes) Our toes are straight, whereas in apes they tend to be curved
Provisioning Model
-Males would gather food and bring it back to females—hence, their hands needed to be free to carry these
items
-BUT, this would mean that pair bonding evolved early
Using tools model
-Hands needed to be free to make tools to hunt…
-BUT, don’t find evidence of stone tools until long after bipedalism
Thermoregulatory Model
-Bipedalism confers a reduction in heat gain and facilitation of heat dissipation
But what about the fact that close hominin relatives knuckle walk?
-Comparative anatomy of extant African apes and fossil hominins suggests that humans evolved from a
knuckle walking ancestor
What is a hominin?
-Hominidae, based on genetic evidence includes humans and all great apes
-These are called hominids
-Homininae, based on genetic evidence, includes humans and African great apes
-These are called hominines
-Hominini includes bipedal taxa within homininae
-These are called hominins
Really General Characteristics of Early Hominini
-Bipedal
-Bigger Brains
What is a Honing Premolar?
-A premolar that sharpens upper canine (monkeys and apes)
Hominins: Trend towards non-honing premolar & smaller canines
Sahelanthropus Tchandensis
-Meaning of name
-Sahel = African Region
-Anthropus = Human
-Tchadensis = from Chad
-Biped (?)
-Foramen Magnum
-Canine-premolar complex beginning to be non-honing
Middle Awash, Ethiopia
-Found Ardipithecus Kadabba
-Name
-Ardi = ground
-Pithecus = ape
-Kadabba = original
-Long Phalanges (toes)
LOOK ONLINE FOR ALL OF THESE SLIDES
Bones W8
March 2 , 2017
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Australopithecus species inhabited the African continent between approximately 4.2 and 1.9 million years
ago
-Strong dub-nasal prognathism
-Below the nose, the upper jaw sticks out
-Robust mandibles
-Bones of the lower jaw are bigger and thicker in all dimensions
-Honing Premolar is reduced in Australopithecus
What is Canine Diastema?
-A space between the upper incisor and the lower canine that allows the lower canine a space so that the jaw
can close
Australopithecus
The History of Discovery
Australopithecus Africanus
-Name means
-Australo = southern
-Pithecus = ape
-Africanus = Africa
-Recovered from cave sites in South Africa
-Age: 2.8-2.2 Mya?
-Foramen magnum like a biped
-Bipedalism came before big brains
Australopithecus Afarensis
-Name means
- Australo = southern
- Pithecus = ape
- Afar = region & people of Ethiopia
-Age: 3.8-2.95 Mya
-In 1973, Don Johansson LOOK ON SLIDEs
Lucy, a female Au. Afarensis
-Lucy was discovered a year later in 1974
-Still one of the most complete skeletons of any hominin
Continuing work at Hadar uncovered…
-Sexually dimorphic (canines)- at least as much as gorillas
Kadanuumuu (Big Man)
-Woranso-Mille
-3.6 Mya
-Sexual Dimorphism LOOK ONLINE FOR SLIDES
Australopithecus Anamensis
-Name Means
-Australo = southern
- Pithecus = ape
-Anam = Lake in Turkana
LOOK ONLINE FOR SLIDES
Australopithecus Garhi
-Name means
-Australo = southern
-Pithecus = ape
-Garhi = surprise
-2.5 Mya
-Big teeth, small brain (even though they were relatively young)
Australopithecus Sediba
-Name Means
-Sediba = natural spring
-Dated to 1.9 Mya
-Very small teeth
Kenyanthropus Platyops
-Name Means
-Kenya = the country
-Anthropus = human being
-Platyops = flat face
-Age: 3.5-3.2 Mya
-Small teeth, but broad flat face (like Paranthropus)
What do we know about these species?
Dietary Morphology
-In comparison to Miocene Apes, one of which was the common ancestor to chimpanzees and
Australopithecus
-Large flat, low relief molars with thick enamel
-Good for crushing hard, brittle items
You are what you eat
-Carbon Isotopes:
-C4: Grasses
-C3: Trees & Shrubs
-Can detect isotope signature in tooth enamel
Stone-tool-inflicted marks on a femur shaft of a small young antelope
-3.2 Mya
-Au. Afarensis?
-No actual tools found
-BUT, they could have also been caused by crocs
Lomekwian Tools at 3.3 Mya?
-2011, Kenya
-Large
-If truly tools, the oldest known
-No animal bones with cut marks
