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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
Mammalia&Reproduction

By: Rachel, Nico, Brandon, Lauren

mammalia
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
major characteristics of mammalia
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
groups of mammals
Groups of mammals

Monotremes

Marsupials

Placentals

monotremes
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)
marsupials
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
placentals
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
reproduction of fish and amphibians
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
reproduction of reptiles and birds
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
amniotic egg
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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