Bipedalism and Pre-Australopithecus

What is a Hominin

All human ancestors until our last shared ancestor with Apes

Where did all early human evolution occur

In Africa up until a certain point

Locomotion in modern homosapiens

Bipedal, short pelvis, long legs, bigger body, shorter digits

Locomotion in Early hominin

Bipedal, short pelvis, smaller body, long digits, capable of climbing, ape-like characteristics

Locomotion in Miocene generalized hominin

Quadrepedal, long pelvis, capable of arm swinging, suspensroy locomotion

Brains in modern homosapiens

Greatly increased brain size, highly ecepalized (Brain to body size proportion), 1350 cm^3 brain size

brains in early hominin

Larger brains than miocene form, moderatly ecepalized; prior to 6mya, no more encepalized than chimps

Brains in miocene generalized hominin

Small compared to hominins, large compared to other primates, fair degree of ecepalization,

Tools in modern humans

Complete cultural dependecy on tools

Tools in early hominin

Stone tools start at 3.3 mya, more oriented tools than chimps

Tools in miocene generalized hominin

uknown tool usuage, probably similar to chimps

Human evolution features

Bidepal, brain size increases over time, more parabolic jaw structure, teeth decrease in size over time, reduced sexual dimorphism, extended parental care

Major features of hominid bipedalism

Foremen magnum in under the skull; spines have distinct curves in an S shape; pelivs is short, shaped like a basin to support internal organs; femur goes in at an angle when standing; enlarged big toe that is brought in, arch on foot

benefits of bipedalism

Free hands, see landscaoe better, travel between areas on grouns easier, more engery efficient, change in feeding posture, ability to provision

Distinct Hominin fossil records

Apes have CP3, humans do not; Apes canines need to be sharpened, humans' do not; Hominins have CP3 appearence, but it does not work; bipedalism

When were preaustralopithecus around

7-4 mya

What are the types of australopithecus, when were they around

4.2-1 mya; gracile and robust australopithecus

What are the most commonly found fossils

Teeth, bones rarely fossilize completely

Do we have evidence of two species at the same place during the same time

No

What are the species of preastralopithecines

sahelanthropus tchidanensis, orrorin tygenensis, ardipithecus kadabba, ardipithecus ramidus; all date 7-4 mya

Describe sahelanthropus tchadensis

earliest preastralopithecine, discovered in 2001, large brow ridge, sagittal crest, small brain, first hominin

Describe Sahelanthropus Tchadensis

large brow ridge, smaller canine teetch, no diastema, non functioning CP3 complex, small brain, u shaped dental arcade

Describe orrorin tygenensis

dates 6 mya, appears to be hominin, teeth with enamel

What are the species of australopithecines

africanus, gahri, afarensis, anamenus, date 4.2-1 mya

Describe australopithecines

small cranial capacity, 60-100 lbs, moderate prognathism, moderate teeth size,

Describe australopithecus afarensis

Lucy

Skull volume: 400cm(cubed)

Height: 3.5ft

Description: Could walk upright but toes were more cubed although the bones were arranged in the same way humans are today

Discovered : 3.9-3 million years ago

Describe A. Gahri

Only australopithecine found with stone tools

What is hominin phylogeny

Used to figure out which groups are related to which, there is no clear understanding of how all groups relate tho

Describe robust australopithecines

Found in east and South Africa. Larger cheeck teeth and reduced anterior teeth. Sagittal crest. Broad cheek bones. Postorbital construction. Highly derived "chewing machines".

What happened to robustus

hit evolutionary dead-end; specialized for enviroment, enviroment may have chaged