Unit 3: Paleoanthropology and the Fossil RecordPaleoanthropology - The study of human evolution, the hominid fossils, and their relations to each other andmodern humans - There is nothing outside Africa that is even in the running to be a potential human ancestor - The most fossils are found in East Africa in the Rift valley, several in South Africa, and afew in Central Africa - Goalso ID the early hominid species, consider how they are different from modern ageo Establish their relationships to one another o Gain insight to their behavior - “The big 3”o Culture  Religion, art, ritual, etco Brain Size  Primates are more encephalized than other mammals Relative to their body size they have bigger brains Within primates only, humans are the most encephalized o Bipedalism  Walk habitually on two feet; have no other ways of walking There are differences in the skeletons between bipeds and quadrupeds o These three things did NOT happen at the same time *****Skeletal Adaptations for Bipedalism***- Skullo Foramen magnum: The hole through which the spinal cord passes, centrally underneath the skull- Spineo Curvatureo This puts the head directly on top of the skeleton so the head is not out in fronto Helps us maintain balance o The great apes have a slight curvature but it’s not as great as our curvature is- Pelviso The ilium/ilia are oriented in an anterior/posterior directiono This helps position the muscles o We find the pelvis in the fossil record - Femuro Bicondylar Angle: referring to the angle that the femur makes in its anatomicalposition from the hip to the knee, made from the bottom of femur to hip It is unnatural to stand with our legs hip length apart because of the bicondylar angleo Neck Length The length of the neck is correlated to how far out the femur will extend In a chimp, the neck length is shorter In a biped, the neck will be longer o Feet Great Apes have an opposable big toe  Humans have a derived foot with all the toes being in one line Bipeds have arches in their feet which helps to stabilize weight Great Apes do not have an arch  Apes arms are longer than humanso Arboreal Apes have elongated and curved toes and fingers to live in trees Humans do not Apes cannot get a flat band because of a ridge in their wrists so they walk on their knuckles Humans can get a flat hand and do not have a ridgeHypothesis for Bipedalism- Have to do with being on the ground and freeing the hands to carry thingso Tools, food, infants (carrying)o Feedingo Hunting- To have a better view of the open countryo Seeing over tall grasso Traveling between trees- Energy efficiencyo Better energy use to walk on two legs as opposed to 4- Family Provisioningo Males providing hunted meat for “families”o Females providing gathered fruits and nutso BehaviorsLumpers and Splitters- Even the experts do not agree on this- Lumper – paleoanthropologist that want to put all the fossils into fewer categories- Splitters – suggest that the differences can speak for themselves, it’s ok to maintain many different categoriesEast Africa vs. South Africao Geology –  East Africa – known as a Rift valley because it is where two land masses are butting up against each other - Resulted in earthquakes and volcanic activity- Ideal for getting dates for a site- The fossils are generally well preserved because of the volcanic activity  South Africa – lots of limestone- Ground water will erode a fissure in the surface and will either become larger or will form a cave underground- Things get trapped in the caves; if it was an animal it dies in the caveo Over time a brechia develops Brechia – a hard matrix that is composed of sand, debris, pebbles, etc and forms around the fossils- Because it is so hard, when fossils are found encased in brechia, it can be very difficult to remove them- The dating of a South African site is by biostratigraphyo Relating it to something elseo The South African sites are a lot more general- The fossils are found through quarry activities (limestone quarries)  Central Africa – more like East Africa- Fossils are not found through quarrying activitieso Taphonomy – the study of something after it dies; includes becoming a fossilMiocene Fossils- Sahelanthropus tchadensiso Nearly complete skull that is small brained and it has someape like characteristics o The position of the foramen magnum suggests bipedality so that makes it a great last common ancestor (LCA) candidate between apes and humanso 6-7 million years old Oldest possible hominido Geography – found in Central Africa  Unexpected since most fossils are found in East or South Africa Miocene/Pliocene Fossils- Orrorin tugenensiso Found in Kenya (East Africa)o Multiple individuals representedo The teeth are more ape-like in their morphology but evidence of bipedality in the femoral neck length - Ardipithecus ramiduso They link it to sahelanthropus tchadensis So it is also a great LCA candidate between African apes and humans o Falsifies the idea of a chimp-like last common ancestor because it doesn’t look like a chimpo Small brainedo Bipedalo Also was capable of moving through the trees (opposable big toe)o Found in East AfricaPliocene Fossils- Kenyanthropus platyopso Nearly complete skull that is fairly old (3.2-3.5 mya)o “flat faced man from Kenya”o Small brainedo Big brow regions but a flat faceo Found in 1999o Date: Australopithecuso Morphologyo Not much information on ito Contemporary with another hominid genus (Aust.) meaning it lived at the same time, but its features are more human-like or derived o Not in the genus homo but it is very similar to later fossils that are o Makes it a better candidate for the human lineage than the Aust. o Date + derived = ancestorAustralopithecus- A. afarensiso 3.9-3 myao Only found in East Africao At least 120 individuals found (well represented)o Skull shows it was small brainedo Had a small degree of post-orbital constriction o Small to no sagittal crestso Have large brow ridgeso Large nuchal cresto Fairly prognothic – gives a concave appearance to the face o Teeth = ape-like (very large canines)U shaped dentition (the sides are parallel to each other)o Postcranially, evidence of bipedality o No opposable big toe o 3.5-4 feet tallo Long armso knuckle walkingo Size of a chimpanzeeo “Lucy”Found in 1974 A. afarensisSingle individual that is relatively completeShe