ANTH 210 Lecture Notes - Lecture 9: East And Central Africa Cricket Team, Aegyptopithecus, Geologic Time Scale
3 May 2018
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Lecture'9'–'Primate'Origins'&'Early'Hominins''
THE$EARLIEST$PRIMATES$
• Geologic(Time(Scale(
o A'standard'division'of'Earth'history'
into'eons,'eras,'periods'&'epochs'
based'on'large-scale'geological'
events'
o Geologists'have'broken'down'the'
history'of'the'Earth'
o We'are'now'considered'to'be'in'a'
new'epoch'because'the'
climate/environment'has'changed'so'
much'
• Paleoclimates(
o 65'million'years'ago'dinosaurs'went'
extinct.'The'planet'used'to'be'a'lot'
warmer'&'wetter'than'it'is'today'
o Slight'changes'in'climate'can'have'
major'impacts'on'the'evolutionary'
development'of'certain'species'
o The'time'scale'on'the'right'consists'of'the'Quaternary'&'Tertiary'periods;'there'
are'also'Cretaceous'&'Jurassic'Periods'
• K-T(Extinction(
o The'Cretaceous-Tertiary'(K-T)'mass'extinction'event'resulted'in'the'extinction'of'
¾'of'the'world’s'reptiles,'mammals'&'birds'approximately'65'mya.'
o Believed'to'have'been'caused'by'the'impact'&'resulting'fallout'from'a'large'(~6'
mi-diameter)'iridium-rich'asteroid'or'comet.'
2'
o Diet'played'the'largest'role'in'survivorship;'omnivores'&'insectivores'were'more'
likely'than'others'to'survive'the'event'
§ Survivorship'changed'towards'smaller'creatures'&'mammals'
• Proto-Primates(
o Appeared'during'the'Paleocene'(65-55'mya)''
o Primate'common'ancestor'were'small'insectivores'that'caught'insects'
in'trees''
o Primates'won'the'tree-living'fruit'&'leaf-eating'niche'
• True(Primates(
o The'earliest'true'primates'appear'during'the'early'Eocene'(58'&'34'
mya)'in'Africa,'Europe,'Asia'&'North'America''
o Forest'Eocene'environment'is'quite'dense''
o Old'world'monkey'ancestors'appear'during'the'Eocene/Oligocene'
around'30'mya'at'an'Egyptian'site'called'Fayum'
o Aegyptopithecus$zeuxis'was'an'early,'medium-sized,'diurnal'&'
arboreal'monkey'(Aegypto'='king)'
§ They'developed'more'traits,'but'are'still'in'similar'
niches/habitats'as'photoprimates'
• True(Apes(
o The'1st'true'apes'begin'to'appear'during'the'early'Miocene'epoch,'around'25'
mya,'with'remains'recovered'from'East'&'Central'Africa,'Europe,'Central'
Asia'&'Southeast'Asia(
o Species'include'genus'Proconsul'(pictured'on'the'right),'Kenyapithecus,'
&'Dryopithecus(
o Some'are'arboreal'quadrupeds'(tree-dwelling,'walking'on'4'limbs)(
o Others'have'larger'bodies,'better'for'feeding'on'low'branches'or'forest'floor(
§ As'size'increases,'animals'become'better'adapted'to'lower'ground(
§ This'shift'in'size'is'important'for'the'birth'of'hominins(
§ This'became'more'favourable'for'the'open,'drier'grasslands'that'
eventually'became'the'Earth’s'climate(
• Miocene(Apes((
o One'of'many'unresolved'issues'in'paleoanthropology'is'the'unclear'ancestry'of'
today’s'African'great'apes.'No'chimp/bonobo'or'gorilla'fossils'have'been'found'
post-dating'their'respective'divergences'from'our'ancestral'line(
o Upper'Miocene'Fossil'Gap:'12'–'6'mya,'very'few'fossil'bearing'deposits'in'Africa'(
o It'is'clear'that'during'this'period,'our'evolutionary'line'diverged'from'that'of'the'
Miocene'apes.'The'resulting'line'of'hominins'began'spreading'rapidly'
throughout'East'&'Southern'Africa(
INTRODUCING$HOMININS$
• Taxonomy(
o Hominoid'(superfamily)'='Gibbons,'great'apes'&'humans'(NO'monkeys)'
3'
o Hominid'(family)'='all'great'apes'(organgutans,'gorillas,'chimpanzees)'&'humans'
(NO'gibbons)'
§ Gibbons'are'less'similar'to'Great'Apes'than'humans'(they’re'just'slightly'
smaller)'
o Hominin'='all'species'related'to'humans'since'the'split'from'Chimpanzees'
• Characteristics(of(Hominins(That(Differentiate(Them(from(Apes((
o Upright'posture'&'bipedal'gait'
§ Increasingly'habitual/obligate'bipedalism'
§ Reflected'in'changes'to'pelvic,'leg,'&'foot'anatomy'
o Changes'in'dentition'(for'drier,'coarser'veggies)'
§ Reduced'canines/enlarged'premolars'&'molars'
• In'response'to'the'shift'towards'a'drier'environment'during'the'
Pleistocene'
§ Overall'reduction'in'size'of'teeth'relative'to'body'size'
§ Dental'arcade'becomes'more'parabolic'(curved)'
§ Premolars'&'molars'develop'shorter,'rounder'cusps'
§ Thicker'tooth'enamel''
• Adaptation'to'tougher'food'grain'
§ Reduced'prognathism'
§ Human'teeth'info:'
• Adult'human'has'32'teeth,'grouped'
into'4'classes:'
o Incisors'(8)'
o Canines'(4)'
o Premolars'(8)'
o Molars'(12)'
o Enlarged'brain'size'(later'species)'
§ Visible'through'increased'cranial'capacity'(cc)'
§ Reduction'in'cresting'(bony'fins'on'head'for'muscle'attachment)'
• Sahelanthropus(tchadensis((
o 6'–'7'mya'
o In'2002,'a'French'team,'led'by'Michel'Brunet,'discovered'a'
nearly-complete,'but'distorted'fossilized'cranium'in'
northcentral'Chad'(central'Africa)'
o Nicknamed'“Toumaï”'='“hope'of'life”'
o Had'an'unusual'combination'of'ape'&'hominin'characteristics''
o If'Toumaï'is'a'hominin,'it'would'be'the'earliest'yet'recorded.'
o Foramen$magnum'(hole'where'spinal'cord'enters'skull)'
position'changed'for'a'more'bipedal'animal'
o A'transitional'species'between'hominin'&'apes''
• Ardipithecus(ramidus(
Document Summary
Lecture 9 primate origins & early hominins. Asia & southeast asia: species include genus proconsul (pictured on the right), kenyapithecus, & dryopithecus: some are arboreal quadrupeds (tree-dwelling, walking on 4 limbs, others have larger bodies, better for feeding on low branches or forest floor. As size increases, animals become better adapted to lower ground. This shift in size is important for the birth of hominins. This became more favourable for the open, drier grasslands that eventually became the earth"s climate: miocene apes, one of many unresolved issues in paleoanthropology is the unclear ancestry of today"s african great apes. No chimp/bonobo or gorilla fossils have been found post-dating their respective divergences from our ancestral line: upper miocene fossil gap: 12 6 mya, very few fossil bearing deposits in africa. It is clear that during this period, our evolutionary line diverged from that of the. The resulting line of hominins began spreading rapidly throughout east & southern africa.
