Mammalian Evolution

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Author:
jennnn
ID:
85143
Filename:
Mammalian Evolution
Updated:
2011-05-11 16:34:39
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esci
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earth history
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  1. Characteristics of mammals
    • -live birth
    • -endothermic
    • -fur or hair
    • -mammary glands
  2. Synapsid
    • first phase of mammalian evolution-pelycosaurs- sailbacked 'reptiles'
    • -elongated neural spines - surface area allows blood to cool
    • -therapsids
    • -mammals
  3. therapsids- transitional characteristics
    • mammal like 'reptiles'
    • -developed heterodont teeth, tripartite division of jaw muscles
    • -reduction in number of lower jaw bones- they evolved into ear bones
    • -buttressing of skull
  4. the first true mammals
    • tree dwelling - small bodied - insectivorous - nocturnal
    • (marsupial like)
  5. Evolution in Cenozoic
    • extinction of dinosaurs opened up niche space for diversification
    • Planet began to cool, transition from greenhouse earth to icehouse earth
  6. Miocene-
    • continued cooling trend with warmer periods - evolution of grasslands- first horses
    • -they evolved larger teeth and body sizes because height gave advantages in tall grass
  7. Great American Interchange
    • North and South America were connected by a land bridge in the Late Pliocene
    • -sloths armadillos, anteaters, porcupines and opossums headed north
    • -squirrels, rabbits, wolves, deer, horses and jaguars headed south
  8. Characteristics of Order Primates
    • -grasping hands (opposable thumbs)
    • -large relative brain sizes
    • -eyes in the front of face
    • - post-orbital bar (bone behind eye)
    • -origin of primates- prosimian like animals from Late Cretaceous
  9. Anthropoids vs Prosimians
    • Anthropoids-New and Old world monkeys, humans
    • -even larger relative brain size
    • -post-orbital closure
    • -fused mandibular synthesis
    • -nails
    • Prosimians- lemurs, tarsiers - have open eye orbits, smaller, grooming claws
  10. Paleocene- beginning of Cenozoic
    • Hominoid fossil sites in East Africa
    • -rifting in NE Africa - develops MOR, rift basins that did not separate enough to fill with basalt, later filled with sediments, preserving hominoid fossils
  11. Hominid evolution
    • Primitive Australopithicus
    • Laetoli footprints show bipedality and possible family structure
    • Intermediate Australopithicus
    • robust- relatively smaller brains, large jawline and teeth
    • gracile-smaller teeth and jaw, developing forehead
  12. Evolution of Genus Homo
    • Homo Erectus- first hominoid outside Africa
    • -developed tools
    • Neandertal- found in Europe, East Asia
    • Cro-Magnon
  13. Theories - Out of Africa Model vs. multiregional
    • No connection between homoerectus and
    • homosapiens sapiens
    • All modern homo ss descend from homoerectus but evolved separately in each region
  14. Anthropoid superfamilies
    • New World monkeys-South and Central America arboreal, no opposable thumbs
    • Old World monkeys-native to Africa and Asia, baboons, colobus monkeys
    • Hominoids- chimps, gorillas, humans and orangutans
  15. Hominoid traits

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