1. 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 1.Monotremes 2.Marsupials 3.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. Reproduction

9. Reproduction of Fish and Amphibians FishAmphibians External fertilization 1.Lay lots of little eggs: ▫Each egg has lower chance of surviving ▫Requires less energy ▫Mostly Osteichthyes 2.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