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Lecture 19

BIO SCI 94 Lecture Notes - Lecture 19: Insectivora, Thumb, Hominidae

Biological Sciences
Course Code
Nancy Burley

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Primate Traits
Transitional forms evolved from tree-living insectivora in Mesozoic
Oldest fossils 55 mya
Order Primates
Arboreal adaptations:
Dexterous hands, feet; partially or fully opposable thumbs/ big thumbs
Frontal eyes; color vision
Short jaws; short snouts
Large brains, complex social behavior
Slow rates of reproduction/ low fecundity
Prosimians: pre-monkeys
First branch; before K/T extinction
Anthropoid: monkeys and apes (45 mya)
Hominids: great apes = chimps, gorillas, orangutans, humans
Common ancestor of Pan (chimpanzees) and Homo lived about 6 (5.8 mya)
Estimates of DNA similarity: 95-99%
Hominin: humans and all relatives since the split with the lineage that led to chimps
“Human” = Homo
Fallacy: hominins evolved early to hunt large mammals
Early humans were actually consumers/scavengers; not humans
Fallacy: hominins are in a straight, single lineage leading to humans

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There are actually many branches; humans are the extant species
5-2.2 mya
Long lived genus
All fossils > 1.9 mya are usually from east/southern Africa (Hominins)
Homo sapiens: 2.3 mya - present (debatable)
Dry weather from Cenozoic era causes faster decomposition of fossils → inconsistent or
skippy ages of fossils
First innovation of hominins: bipedalism
> 4 mya
Drier climate, forest receded → more grasslands
Savannah ( grasslands + trees)
Biomechanical reconstruction of gait of Australopithecus; similar to how apes
walked and distance wise
Australopithecus afarensis
“Ape brain and human body”
Bipedal, upright
Small groups
Over 100 fossils
Arms remained long; curved fingers
Australopithecus garhi
Tool maker → extracting bone marrow; meat eater
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