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Lecture 5

ANTA01 - SUMMER 2012 - LECTURE 5 - PRIMATE ORIGINS

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Department
Anthropology
Course
ANTA01H3
Professor
Carolan Wood
Semester
Summer

Description
ALL MC  LECTURE, TUTORIAL, READINGS (1-8)  60 MC PRIMATE ORIGINS  hard time classifying fossils due to:  fossils indiv vary  age differences (6yo vs adult)  sexual dimorphism – diff in b/w sexes  if no pelvis – could not differ male or female  change w/in species over time  End of cretaceous period – have separation of continents  Brought new ecological niches  Climate became MILD  new vegetation  Spread of tropical/subtropical forest  Move to arboreal life (life in trees)  Place of origin of 1 primate UNKNOWN – but we looking at beginnings by 60 mya THEORIES OF PRIMATE ORIGINS  ARBOREAL THEORY  Move for better way to move thru trees  Need for stereoscopic vision (3d vision) – grasping hand/foot  VISUAL PREDATION THEORY (MATT CARTMILL)  3d vision and grasping, nails over claws, better for hunting insects  origin was probably insectivore TIMELINE OF PRIMATES (CHART FROM HAVILAND)  KT EVENT  Cretecoius, terteiary extinction event (KT, not CT) wtf..  70% of all species went extinct  allow for adaptive radiation of mammals- due to more niches to fill  from 65 to 55 mya  EOCENE (55-34 MYA)  Some primates w/ some features of modern prosimeons  OLIGOCENE (34-24)  Monkey and apelike features  MIOCENE  24-5 MYA  monkeys and diff kinds of apes appearing PALEOCENE (65-55MYA)  earliest primates did appear – most was contested  called plesiadaptiformes – found in Europe and NA  grasping ability  dentition adapted for fruit eating  and long arms suited for tree life  eg. Purgatorius – like a rat  a bit contested – some say earliest primates – were missing lot of picture in between EOCENE 55 – 34 MYA  earliest recognized primates  anthropoid existence is greatly disputed  find these guys in Africa, NA, Europe and asia  climate was warm and wet, lots of rain  types of primates:  lemur like adapids and tarsier like omomyids (persimmeon like)  fossils show a rounder braincase  short snout (less reliance on smell, more on vision)  more forward facing eyes (for 3d visions)  some nails OLIGOCENE 34 – 23 MYA  earliest undisputed anthropoids  prosimians less common  ancestors of NW monkeys = platyrrhines  Australia has no actual primates  Prominence and diversity of haplorhines – monkeys and apelike primates  eg. Aegyptopithecus  fossils show ape like dentition 2123  brain – larger visual cortex  yet still have more monkey like skull and body  quadrapedal – locomotion on all 4s  sexual dimorph – males larger than females MIOCENE APES 23-5 MYA  proliferation of apes throut  old world forests  generally, dentition is more ape like  but postcranial (skull down) is more monkey like  limb bones for suspension  Genus Proconsul (famous of these) 20-17mya  Unspecialized tree-dwelling fruit eating hominoid (apes and humans)  Overall, they were closer to apes-human lineage than old world monkeys DIVERGENCE  First great ape to diverge are oran  Separate b/w 10-12 mya  By Miocene see ape like primates  Ancestral primate to orans = sivapithecus (found in Indonesia)  Like a pre orang  Regarding chimps and gorillas we have – dryopithecus  b/w 4-6 mya – apes and humans are separated from common ancestor (end of Miocene)  10-12 miocene – orang split  4-6 – us and ours sep from great apes  by 4 mya we have undisputed bipedal hominins (most in east Africa) BETWEEN MIOCENE APES AND AUSTRALOPITHECUS  3 possibilities  1 . Sahelanthropus tchadensis (in Chad of Africa)  7-6 mya  possibly bipedal – based on forward location of foramen magnum  in bipideal – shud be directly undneath  in quadropeds – will be behind  Hominoid – small brain, large brow ridges, wide face  Teeth were very HOMININ – canines don’t project below other teeth nd  2 . ORRORIN TUGENENSIS (east Africa)  around 6mya  incisors and canines are more ape like  molars are thick enamel like the australopithecines, but smaller  suggests bipedalism (not all agree with this)  uncertain evolutionary rlsp (not sure if this was indivu that carried on to next or branched off to become something else)  3 . ARDIPITHECUS RAMIDUS (E AFRICA)  dates 5.8 to 4.4 mya  likely bipedal when on ground – b/c of foramen magnum  mixture of ape and hominin dental features (thin enamel)  forested envi (not like the savanna BIPEDALISM  separated humans from ancestors from apes  most crucial change and most defining one at this time POSITION OF FORAMEN MAGNUM  CHIMP – angle is getting more acute  Prognathism – how much face projects forward (less w/ bipedalism – more on changing diet)  Reduce muscular of neck b/c head balance on back bone – doesn’t have to be forward SPINAL CURVATURE  Ape – spine is rel straight  Humans have s curve – forward curve neck  Forward curve in lower back  Serving as – legs have to bear all weight – need to balance on one leg  Absorbs shock  Allows u to stand on one leg  In addition – femur repositioned in humans  In apes - directly above  Humans – knees are positioned inwards to balance weight  Tend to have this unsymmetrical knee joint for humans  Apes joint come together – straight on top of each other  For us – off to the side PELVIS AND LEG LENGTH  Human pelvis  More bowl like, broader, lower, not elongated  Lowers our centre of gravity  Human leg – longer than arms  Apes will be equal  Will be increased width of female pelvis  Giving birth to larger headed babies  Ultimate maladaptive traits  Increased plasticity of infant head – so it can move and twist thru birth canal FOOT  Arched feet  No longer have opposibl
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