1. Amniotic Egg Suite of special membranes with various jobs (store nutrients, gas exchange, waste storage) Shell (in some) for protection + waterproofing, can lay eggs in more exposed locations Figure 34-16 Shell Yolk sac contains nutrients Embryo Mammals dispensed with shell and embryo avoids desiccation by developing within mother

3. Dino EGGS Dino rookery-nests 23ft apart Lots of parental care Communal nesters

4. Birds and mammals have amniotic egg too! Mammals also have…Mammary glands... nourish offspring with milk-Ramifications….???? Offspring can grow fast and over a long period... Don ’ t have to feed themselves (offspring can be born in locations that don’t support them directly) Not dependent on abundance of prey Mom can store energy in the form of fat to feed young

5. ANCESTRAL AMNIOTE Amniotic egg Reptiles Mammals Synapsids Early mammals split from Synapsids Mammals only surviving lineage of Synapsids Rest of Synapsids went extinct at end Permian extinction event (250mya)

6. WITHIN MAMMALS.. Eutheria=Placentals Metatheria=Marsupials Prototheria=Monotremes

7. Monotremes Eggs w/ soft shells echidnas incubate their eggs in their pouch platypuses incubate eggs in nest Milk-oozes out of skin onto fur Highly altricial

8. Marsupials Born at very premature stage…(highly altricial-equivalent to 8-10 wk old human embryo) (no precocial young) Shorter period of diffusion of materials between mom and baby Pouch with nipples inside-permanently attached at start..ex utero development

9. What cool pouch facts did you learn about (open up pouch paper)?? Gas exchange through skin! Ectothermic! Immune system underdeveloped! No lymph system! Advantages to pouch vs long pregnancy? Bad conditions? Toss offspring! Note: Is a kind of yolk sac which delivers nutrients In some species there ARE placenta like organs but not clear whether nutrients are transferred.

10. Marsupials are much less diverse than placental mammals in terms of range of lifestyles, range of body shapes and where they live. One hypothesis for why no fully aquatic or flying species has to do with reproduction….

12. Thylacosmilus (left / source) and Borhyaena (right / source).source http://www.palaeontologyonline.com/articles/2012/fossil-focus- marsupials/

14. http://www.plosbiology.org/article/inf o%3Adoi%2F10.1371%2Fjournal.pbi o.1000436 Marsupials reached Australia 50 mya Placentals were there in Australia but went extinct Left Marsupials as only mammals

15. One group of mammals=Eutherian=Placentals have a Placenta! Very specialized membranes for transfer of nutrients….transfer of nutrients is high! Figure 34-17 Yolk sac Chorion Amnion Embryo Allantois Placenta Mother’s uterus

16. Placentals or Eutherians Chorioallantoic placenta- “ even more specialized tissues ” -provide nutritional, respiratory and excretory exchange between mom and offspring So young can spend even more time developing in mom so…. more developed when born (altricial to precocial) Pathogen free! (well…)

17. No evidence that one evolved first…or that one is less advanced..Different solutions to different selective environments. Why would selection favor a long gestation or short gestation?