Chapter 43 Mammals

1. Chapter 43Mammals 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.