Terms continued Paleoanthropology Paleoanthropologists who look at the fossil record and want to Paleoanthropologists that recognize and emphasize differences Lumpers lump many of them together Splitters and tend to split them into many groups Gracile smooth and rounded Robust are rougher and thicker Spoiler understanding Species that has small muscle attachments so the bones are Species that has large muscle attachment areas so the bones referring to fossil found that challenges the traditional Post Orbital Constriction POC the narrowing of the skull immediately behind the eye orbit o Correlated with brain size Humans have large brains there is no post orbital constriction Supraorbital Torus SOT an enlarged area of bone above the eye orbit brow ridge o not found in humans o found in chimps apes and gorillas Prognathism anterior projection of the maxilla Orthognathism vertical nearly vertical maxilla o Found in humans Sagittal Crest enlarged ridge of bone located on the top of the skull runs anterior posterior front to back Nuchal crest enlarged ridge of bone in the back of the skull at the base o Primitive characteristic projects where muscles attach Paleoanthropology East Africa o Geology Rift valley two continental plates meet Volcanic activity earthquakes Pretty good environment for fossil preservation o Dating Potassium Argon 40 Remember that s the absolute dating used on volcanic rock South Africa o Geology Limestone formation Subterranean caverns Fossils are found through quarrying activities or in caves Well preserved BUT they are encased in Breccia o A cement like substance of sand debris and o Removing the fossils without damaging them is limestone difficult o Dating Relative Biostratigraphy Miocene Fossils Sahelanthropus Tchadensis fossil that may or may not be a Hominin o 6 7 mya o Oldest o Found in Central Africa in Chad o Primitive cranium it was ape like Small brain Post orbital constriction Sagittal crest Nuchal crest Supraorbital torus o Relatively flat maxilla and small canine teeth o Possibly bipedal Foramen magnem Miocene Pliocene Fossils Ardipithecus Ramidus Ardie o Skeletal representation o mix of ancestral and derived traits Ancestral Derived 3 5 small brain relatively gracile very reduced sagittal crest opposable big toe elongated arms No knuckle walking or brachiation adaptations pelvis was neither quad flat nor bipedal bowl o Hominid o Capable of bipedalism but not efficient o Similar to chimp in size not appearance o Spoiler People assumed the last common ancestor would more closely resemble a chimp Pliocene Fossils Kenyanthropus Platyops o 3 5 3 2 mya o Small brain slightly larger than Ardie o Post orbital Constriction little bit less o Small moderate sized crests Sagittal and Nuchal o Spoiler running around at the time all features are a little more derived than other creatures o More similar to other fossils in our genes o In this time period with these slightly more derived traits is this an ancestor a better candidate Australopithecus o Australopithecus afarensis 3 9 3 0 mya Geography East Africa 100s of specimens Cranial Traits With a minimum of 120 individuals Small brain Post orbital Constriction Small moderate crests Sagittal Nuchal and Supraorbital Torus Prognathic Dentition o U shaped palatte o Large molars and canines Post Cranial Traits Short 3 5 4 Neither flattened nor rounded hips Type of bipedal Wide bicondular angle No opposable big toe Has the adaptation for knuckle walking Long arms compared to the leg length Long femoral neck Lucy AL 288 1 We have a nearly complete jaw little of the skull several vertebrae a femur 50 of the pelvis Importance o Well represented skeletally we have maybe 40 o Shows adaptations for bipedalism Selam DIK 1 1 Well represented skeletally roughly 60 a child skeleton maybe 3 4 years old at death Complete skull vertebrae scapula shoulder Unknown gender you can t tell gender from a child skeleton Laetoli A dig site 3 4 myo Eastern Africa Where 2 sets of bipedal footprints were discovered o Indirect fossils confirms bipeds at the time Spoiler it was long thought to belong to afarensus they were long thought to be the only ones walking at the time but we now know of kenyanthropus o Australopithecus africanus 3 2 mya Endocast preserved cast of the inside of a skull Preserves size and shape of the brain Geography South Africa Cranial traits Small brain post orbital constriction etc same as other Australopithecus Bigger molars relative to size of canines Post Cranial Traits Short 4 Bipedalism adaptations Long arms relative to legs Taung Child 3 4 years Good comparison to Salem Preserves evidence of expanded brain Preserved the position of the foramen magnem Minimum of 130 individuals o Australopithecus ghari 2 5mya East Africa Australopithecus are not supposed to have Spoiler used stone tools o But in the late 90 s the earliest set of stone tools and butchered animal bones were found near down the road from a ghari o Possible tool user o Australopithecus aethiopicus 2 7 2 5 mya East Africa Small brain pronounced post orbital constriction pronounced crests wide face widely flaring cheekbones High degree of prognathism U shaped palette Gigantic teeth molars Black Skull WT17000 o Australopithecus boisei 2 3 1 2 mya East Africa Small brain Post orbital constriction More similar to aethiopicus in that it has larger muscle attachment areas sagittal nuchal supraorbital torus Prognathic U shaped palette Gigantic molars megadont very robust cranium bipedal short o Australopithecus robustus 2 1 5 mya South Africa Cranial Post cranial Bipedal Similar to boisei o Time Variation Debate Similar to boisei Teeth not quite as big still megadont Any large variation in the fossil record over time will cause debate among paleoanthropologists Gracile and Robust groups Proposed Robust genus Paranthropus o P aethiopicus o P boisei o P robustus Most of the differences between Gracile and Robust are found in the teeth and skull o Little post cranial differences Dietary Specialization Suggested the larger teeth are due to a dietary specialization coarser more fibrous foods Australopithecine Subsistence How they obtain food shelter Foragers o Not hunters Probably lived in small groups Early Homo Homo habilis o 2 4 1 6 mya o The genus homo our genus is a big statement about relation to us o Habilis Latin skillful o Directly associated with earliest stone tools o Cranial Traits Average of 20 increase in brain size Reduction in Post orbital