1. Chapter 43 Mammals Section 1 Origin and Evolution of Mammals

2. Characteristics Endothermy- regulate own body temperature- metabolism Hair- all mammals have some hair- made of keratin Completely divided heart- four- chambered heart- no mixing of blood

3. Characteristics Milk- females produce milk to feed offspring- made of fats, proteins, and sugars –Produced by mammary glands- modified sweat glands located on thorax or abdomen Single jawbone- fossils identified by bones Specialized teeth- for eating

4. Ancestors of Mammals Synapsids- gave rise to mammals Single opening in a bone behind eye socket Looked like modern lizards Specialized teeth

7. Therapsid Also gave rise to mammals Rich fossil record of transitional forms between therapsids and mammals exists

9. Early Mammals Dinosaurs co-existed with mammals Early mammals were about the size of a mouse Large eye sockets suggests that early mammals were active at night

11. Diversification of Mammals Monotremes- oviparous- lay eggs Marsupials- viviparous- give birth to live young- young develop in pouch Placental mammals- viviparous- develop in mother’s uterus- nutrition from placenta

12. Monotremes

13. Marsupials

14. Placental Mammals

15. REVIEW!!! What is the function of hair in mammals? Differentiate between monotremes, marsupials, and placental mammals.