Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Epoch65 mya55 mya36 mya24 mya1.7 mya(http://www.ucmp.berkeley.edu/cenozoic/cenozoic.html;22 Feb 2005)5 myaThe Earliest Hominidsarchaic primates (disputed)(Plesiadapiforms)Undisputed primates:prosimians proliferateAnthropoids proliferate:Platyrrhine/Catarrhine splitLate Eocene: Catopithecusfirst HominidsCercopithecoid/Hominoid splitTerminal Miocene EventLate 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 ormosaic of ape-like and human-like characteristicsThe first distinctively human character is bipedal locomotionBut the brain remained the size of apesPossible 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 terrainBipedalismBut earliest human ancestors still climbed trees, tooThe genera of early hominidswe’ll concentrate on1. Ardipithecus 5.8-4.4 mya, e Africa2. Australopithecus 4.2-1.8 mya, e and s Africa3. Paranthropus 2.2-1.0 mya, e and s Africa4. Homo 2.5 mya to present But we’ll mention others thatwe don’t know much about yetGenera of possible early hominidswe’ll mention but not concentrate on:Sahelanthropus 7-6 mya, Chad, central AfricaOrrorin 6.2-5.6 mya east AfricaKenyanthropus 3.5 mya east AfricaKnown only from skull and teeth remainsKnown from teeth and leg-bone piecesSkull fragments: perhaps A. afarensisSahelanthropus tchadensis “Toumai”7-6 mya in Chad, central AfricaA nearly complete adult male skull, two lower jaw fragments, three teethHeavy brow ridgesApe-size brain (320-380 cubic cm)Lived in wooded areaDated by faunal assemblage comparisonApes and human orcould be early human:not enough known yet(http://www.talkorigins.org/)Here’s where Salehanthropuswas foundToumaiVOCABULARYPrognathism, prognathic Jutting out of the lower face, forming a short muzzleSagittal crest Ridge of bone along top of skull where temporal muscle connectsZygomatic arch: cheekbone. Temporal muscle inserts behind it(Smithsonian Institution)Postorbital constriction(Turnbaugh et al. 2002:245)Large molars with thickenamel, appropriate forchewing and grindingrough and fibrousplant foodsDentition: 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 timeBig sagittal crest, thick molar enamel reflect a diet of tough, fibrous vegetationDentitionCheek teeth parallel(dental arcade U-shaped)Modern gorillaAustralopithecusafarensis AL2001Modern H. sapiens(Smithsonian Institution)Diastema: Gap where canine slot inParabolic dental arcadeNo diastemaLike apes, early humans had diastema & longish canineEarliest human ancestorsArdipithecus (Ard. ramidus kadabba, Ard. ramidus ramidus) 5.8-4.4 mya East Africa 50+ individuals: cranial, facial, dental, upper limb, hand, foot, collarboneApelike in size, anatomy, and cranial capacitybut bipedalUnlike our earlier thoughts on the rise of bipedalism, Ardipithecus lived in wooded areasFour feet tall110 poundsK/Ar date onash it is inArdipithecus ramidusramidusdating to 4.4 myaArdipithecus ramidus4.4 myaScience News 177(2):24Excavated between 1992-1997,descriptive report on Ardipithecus ramidus (4.4 mya)entire 2 Oct. 2009 issue of ScienceCranial characteristicsCranial capacity ape-sized, slightly smaller than Lucy (A. afarensis)Foramen magnum centeredTeeth canines larger than ours, smaller than modern chimps thin molar enamelScience News 177(2):24Ardipithecus ramidusPost-cranial characteristicsSpinal column some curve at bottom, not as much as usPelvis broad like oursLegs/arms about equal length (like modern monkeys)Science News 177(2):24Feetdiagonally oriented, grasping toes, flat feet= slow-moving, upright walkScience News 177(2):24HandsThumbs not as opposable as oursFlexible wrists bendbackwards for moving quadrupedally on tree branchesScience News 177(2):24Ape-like traits:•Long hands•Grasping feet•No arch in foot•Divergent big toeEarly hominid-like traits:•Flaring illia•Reduced canines•More forward-placed foramen magnumFossil evidence indicates A. ramidus lived in a woodland habitat, not a savanna.Ardipithecus ramidus Has shared characteristic with apes and early hominids(2011 TA slide)•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 ingorilla and in chimp/bonobo lines•Supports hypothesis that bipedalism was an adaptation to a varied environment.What does this mean?(2011 TA slide)AustralopithecusTwo lineages:The gracile lineage AustralopithecusA. anamensis 4.2-3.8 mya, east AfricaA. afarensis 3.9-3.0 mya, east AfricaA.africanus 3.0-2.3 mya, east, south AfricaA. sediba 1.95-1.8 mya, south AfricaAnd the robust lineage ParanthropusAustralopithecus anamensis4.2-3.8 mya in Kenya, east Africa9 specimens: skull, jaw, teeth, long bonesBipedal. Thick enamel on molars.Primitive features: long shearing canine, smallear canal openingnewsimg.bbc.co.ukAustralopithecus afarensis3.9-3.0 mya at Laetoli, Tanzania and Hadar, Ethiopia in east AfricaMany individuals (nearly 100)Both skull fragments and postcranial elementsMost famous is “Lucy,” 40% complete. Also “First Family”(Smithsonian Institution)Australopithecus afarensisApelike: sharp canine teeth withdiastemaDental arcade fairly U-shaped(cheek teeth parallel)Diet of coarse, fibrous vegetationindicated by:Large molars with thick enamel;Musculature of powerful jawsLucy is 40% completedefinitely bipedalA. afarensis
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