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Mammalia & Reproduction

Mammalia & Reproduction. By: Rachel, Nico, Brandon, Lauren. Mammalia. Evolved from reptiles during the Mesozoic era This is around the time when dinosaurs evolved from different reptiles Underwent adaptive radiation to fill major land niches during the Cenozoic era.

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Mammalia & Reproduction

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  1. Mammalia&Reproduction By: Rachel, Nico, Brandon, Lauren

  2. Mammalia • Evolved from reptiles during the Mesozoic era • This is around the time when dinosaurs evolved from different reptiles • Underwent adaptive radiation to fill major land niches during the Cenozoic era

  3. Major Characteristics of Mammalia • Fur or hair • Subcutaneous fat-fat under the skin used for insulation • Most give birth to LIVE young • Mammary glands • glands that produce milk to feed young after birth • Sweat glands • Oil glands • Saliva glands

  4. Groups of mammals Monotremes Marsupials Placentals

  5. Monotremes • Oviparous-lay eggs • Offspring have reptilian-like amniotic eggs • Amniotic egg: waterproof egg that provides nourishment for the embryo • When hatched, baby looks like miniature adult • Found only in Australia and New Guinea • Examples: • duckbill platypus • Spiny anteater (echidna)

  6. Marsupials • Viviparous-give birth to live young • Young are born very early, and so must finish development in the mother’s pouch • Found mostly in Australia and South America • Examples: • Koalas • Kangaroos • Opossums

  7. Placentals • Viviparous-give birth to live young • Capable of longer period of development in mother’s uterus because of placenta • Placenta: made of tissues; allows for oxygen, nutrients, and waste to be transferred from mother to baby or baby to mother • Examples: • Humans • Mice • Whales • Manatees

  8. Mammalia & Reproduction Reproduction

  9. Reproduction of Fish and Amphibians Fish Amphibians • External fertilization • Lay lots of little eggs: • Each egg has lower chance of surviving • Requires less energy • Mostly Osteichthyes • Lay few big eggs: • Requires lots of energy • Egg has greater chance of surviving • Mostly Agnathans • External fertilization • Oviparous-egg laying • Eggs must be kept moist, so most Amphibians lay their eggs in water

  10. Reproduction of Reptiles and Birds Reptiles (Reptilia) Birds (Aves) • Internal fertilization • Most oviparous, some are ovoviviparous • Ovoviviparous-keep eggs internally and bear live young • Development in amniotic egg • Most do NOT care for young • Internal fertilization • Oviparous-lay eggs • Most of development is in an amniotic egg • Egg shell is made of calcium, and so is harder than a reptilian shell • Sometimes birds taken turns having babies and caring for babies

  11. Amniotic Egg Shell: prevents water loss Albumen: extra food Chorion: allows for gas exchange Yolk: provides food for the embryo Amnion: cushions embryo in fluid Allantois: collects waste and helps in gas exchange

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