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Chapter 10

Chapter 10. April 1 st , 2010. Evolution of Mammals. Mammals first appeared 220 mya Small in size; egg layers Small size and warm-blooded physiology allowed some mammals to survive KT Extinction

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Chapter 10

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  1. Chapter 10 April 1st, 2010

  2. Evolution of Mammals • Mammals first appeared 220 mya • Small in size; egg layers • Small size and warm-blooded physiology allowed some mammals to survive KT Extinction • Adaptive radiation occurred as mammals evolved to fill the many vacant niches caused by the extinction of the dinosaurs

  3. Marsupials and Placentals

  4. Angiosperms – flowering plants • Unknown origin • Many primitive living angiosperms in the South Pacific region • Between 100 mya and 65 mya angiosperms increased from 1% to over 50% • Gymnosperms – naked seed • dominate where they can outcompete angiosperms • Disputed origin – first appeared 365 mya • Spruce 159-180 mya; Pine 144-99 mya

  5. Modern Biogeographic Regions • Nearctic + Palearctic = Holarctic • Nearctic = North America, Greenland, and most of Mexico • 13 families of terrestrial mammals • 111 genera of placental mammals • 94 native angiosperm families • Cacti • Horses, camels • Palearctic = Europe, northern Africa, and northern Asia • 18 families of terrestrial mammals • 69 native angiosperm families • Bears, buffalo, moose, caribou, polar bear • 21 shared species of mammals • Different glacial histories

  6. Modern Biogeographic Regions • Neotropical Region – South and Central America and adjacent islands • 23 families of terrestrial mammals • 200 species of endemic rodents • Second highest diversity of marsupial mammals • Most diversity in flowering plants • Cacti • Great American Interchange led to high extinction rates of Neotropical marsupials

  7. Modern Biogeographic Regions • Ethiopian (African) Region – Sub-Saharan African and parts of Arabian Peninsula • Most diverse mammal fauna • Diverse angiosperm flora • Elephants, mammoths • Similarities in flora with Australian and Neotropical Regions • Similarities in fauna with Palearctic

  8. Modern Biogeographic Regions • Oriental Region – Indian subcontinent and adjacent south Asia • 20 families of terrestrial mammals • 108 families of angiosperms • Contains tropical vegetation from Australian, Ethiopian, and Neotropical Regions • Contains montane vegetation from Holarctic

  9. Modern Biogeographic Regions • Australian Region – Australia, Tasmania, New Guinea, and New Zealand • Marsupials • Bats only native placentals • 10 families of terrestrial mammals • 18 families of angiosperms • Crows, ravens, magpies

  10. Marsupials Tasmanian devil Wombat Extinct marsupial lion opossum

  11. Monotremes • Egg-laying mammals • Have cloaca – serves as anus, urinary tract, and reproductive tract • Animalia, chordata, mammalia, monotremata Spiny anteater Platypus

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