Chapter 30 MAMMALS

Existed for 200 million years Therapsids - features of both reptiles & mammals

All mammals have: 1. Hair 2. Mammary glands

Hair: ~Keratin

CLASS MAMMALIA Hair: ~ Insulation ~Waterproofing ~Conserve heat

CLASS MAMMALIA Mammary glands - secrete milk

CLASS MAMMALIA 4-Chambered Heart Endotherms Cooling –Panting or sweat glands

CLASS MAMMALIA Modified limbs 1. Opposable thumbs 2. Various joint types

CLASS MAMMALIA Diaphragm Well-defined teeth 1. Incisors - biting 2. Canines - tearing flesh 3. Molars - chewing

Primates - most intelligent group of animals: - Complex behaviors: - Learning and remembering - Highly developed brains

Parental care - Guard young and teach them

Three types of mammals: 1. Monotremes 2. Marsupials 3. Placental Mammals

MONOTREMES Reproduce by laying eggs Only in Australia, Tasmania, New Guinea 3 species alive today –Spiny anteaters (echidnas) – 2 species –Duck-billed platypus

MARSUPIALS Marsupial - short period of development in uterus, second period inside a pouch Mostly in Australia One U.S. species

PLACENTAL MAMMALS Female carries its young inside the uterus until almost completely developed Gestation - time spent in uterus

VAGINA Uterus - hollow, muscular organ Placenta - O2, nutrition, wastes

COW DIGESTION Cud Chewing - breaking down plant materials (cellulose)

Only in India!