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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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