Epoch The Earliest Hominids Terminal Miocene Event 1 7 mya 5 mya 24 mya 36 mya first Hominids Cercopithecoid Hominoid split Anthropoids proliferate Platyrrhine Catarrhine split Late Eocene Catopithecus Undisputed primates prosimians proliferate 55 mya 65 mya archaic primates disputed Plesiadapiforms http www ucmp berkeley edu cenozoic cenozoic html 22 Feb 2005 Late Miocene 10 5 mya Gorilla lineage splits off around 8 mya 8 4 mya fossil gap when we have few fossil localities with primate fossils Human ancestors split off from chimp ancestors Where are we finding fossils of early hominids What first set humans apart from other apes The earliest human ancestors have a mixture or mosaic of ape like and human like characteristics The first distinctively human character is bipedal locomotion But the brain remained the size of apes Bipedalism Possible factors or influences To move about more efficiently among the scattered trees use less calories to move To be able to stand up for a better view over grasses Ability to carry objects males provision females Stand up to cool off Foraging Bipedal harvesting For display To negotiate rough terrain But earliest human ancestors still climbed trees too The genera of early hominids we ll concentrate on 1 Ardipithecus 5 8 4 4 mya e Africa 2 Australopithecus 4 2 1 8 mya e and s Africa 3 Paranthropus 2 2 1 0 mya e and s Africa 4 Homo 2 5 mya to present But we ll mention others that we don t know much about yet Genera of possible early hominids we ll mention but not concentrate on Sahelanthropus 7 6 mya Chad central Africa Known only from skull and teeth remains Orrorin 6 2 5 6 mya east Africa Known from teeth and leg bone pieces Kenyanthropus 3 5 mya east Africa Skull fragments perhaps A afarensis Sahelanthropus tchadensis Toumai 7 6 mya in Chad central Africa A nearly complete adult male skull two lower jaw fragments three teeth Heavy brow ridges Ape size brain 320 380 cubic cm Lived in wooded area Dated by faunal assemblage comparison Apes and human or could be early human not enough known yet http www talkorigins org Here s where Salehanthropus was found Toumai VOCABULARY Sagittal crest Ridge of bone along top of skull where temporal muscle connects Postorbital constriction Prognathism prognathic Jutting out of the lower face forming a short muzzle Zygomatic arch cheekbone Temporal muscle inserts behind it Smithsonian Institution Large molars with thick enamel appropriate for chewing and grinding rough and fibrous plant foods Turnbaugh et al 2002 245 Dentition Humans and apes have the same dental formula 2 1 2 3 incisor canine premolar molar New trend toward reduction of front teeth initial trend toward larger back teeth but didn t continue enamel thickness on molars varies through time Big sagittal crest thick molar enamel reflect a diet of tough fibrous vegetation Dentition Australopithecus afarensis AL2001 Modern gorilla Like apes early humans had diastema longish canine Diastema Gap where canine slot in Modern H sapiens Cheek teeth parallel dental arcade U shaped Parabolic dental arcade No diastema Smithsonian Institution Earliest human ancestors Ardipithecus Ard ramidus kadabba Ard ramidus ramidus Four feet tall 5 8 4 4 mya East Africa 110 pounds 50 individuals cranial facial dental upper limb hand foot collarbone Apelike in size anatomy and cranial capacity but bipedal Unlike our earlier thoughts on the rise of bipedalism Ardipithecus lived in wooded areas Ardipithecus ramidus ramidus dating to 4 4 mya K Ar date on ash it is in Ardipithecus ramidus 4 4 mya Science News 177 2 24 Excavated between 1992 1997 descriptive report on Ardipithecus ramidus 4 4 mya entire 2 Oct 2009 issue of Science Cranial characteristics Cranial capacity ape sized slightly smaller than Lucy A afarensis Foramen magnum centered Teeth canines larger than ours smaller than modern chimps thin molar enamel Science News 177 2 24 Ardipithecus ramidus Post cranial characteristics Spinal column some curve at bottom not as much as us Pelvis broad like ours Legs arms about equal length like modern monkeys Science News 177 2 24 Feet diagonally oriented grasping toes flat feet slow moving upright walk Science News 177 2 24 Hands Thumbs not as opposable as ours Flexible wrists bend backwards for moving quadrupedally on tree branches Science News 177 2 24 Ardipithecus ramidus Has shared characteristic with apes and early hominids Ape like traits Long hands Grasping feet No arch in foot Divergent big toe Early hominid like traits Flaring illia Reduced canines More forward placed foramen magnum Fossil evidence indicates A ramidus lived in a woodland habitat not a savanna 2011 TA slide What does this mean Adapted to arboreal and terrestrial living Not a knuckle walker This trait evolved in great apes after the hominid line split from great ape line AND knuckle walking evolved separately in gorilla and in chimp bonobo lines Supports hypothesis that bipedalism was an adaptation to a varied environment 2011 TA slide Australopithecus Two lineages The gracile lineage Australopithecus A anamensis 4 2 3 8 mya east Africa A afarensis 3 9 3 0 mya east Africa A africanus 3 0 2 3 mya east south Africa A sediba 1 95 1 8 mya south Africa And the robust lineage Paranthropus Australopithecus anamensis 4 2 3 8 mya in Kenya east Africa 9 specimens skull jaw teeth long bones Bipedal Thick enamel on molars Primitive features long shearing canine small ear canal opening newsimg bbc co uk Australopithecus afarensis 3 9 3 0 mya at Laetoli Tanzania and Hadar Ethiopia in east Africa Many individuals nearly 100 Both skull fragments and postcranial elements Most famous is Lucy 40 complete Also First Family Smithsonian Institution Australopithecus afarensis Apelike sharp canine teeth with diastema Dental arcade fairly U shaped cheek teeth parallel Diet of coarse fibrous vegetation indicated by Large molars with thick enamel Musculature of powerful jaws Lucy is 40 complete definitely bipedal A afarensis was 3 5 5 0 ft tall Sexually dimorphic 50 lbs for females males to 100 lbs Prognathic Small brain 375 550 cubic cm x 440 modern chimps average 390 cu cm Long arms and slightly curved fingers short thumb still climbing trees Walked upright like humans but a partial foot skeleton has long flexible toe tree climbing Bipedal footprints at Laetoli e Africa 3 7 mya www csun edu Gracile Australopithecine Lineage Australopithecus africanus 3 0 2 3 mya in south Africa and east Africa Found at 6 sites Dated by faunal
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