1. CLASS MAMMALIA Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata

2. MAJOR CHARACTERISTICS All mammals share 6 major characteristics : Endothermy Hair Completely divided heart Milk Single jawbone Specialized teeth

3. Endothermy Regulate body heat internally through metabolism and externally through insulation Hair all have some hair Most are covered with a thick coat of hair, which insulates the body against heat loss Hair is made of filaments of keratin

4. Completely Divided Heart Have 4 chambered heart whose 2 ventricles are completely separated by a muscular wall Division keeps deoxygenated blood from mixing with oxygenated blood Allows efficient pumping of blood through the circulatory system

5. GOT M I L K? Females produce milk to feed offspring Milk=nutritious fluid that contains fats, protein & sugars Produced in mammary glands – Modified sweat glands located on the thorax or abdomen

6. SINGLE jawbone Lower jaw is made up of a single bone By comparison, a reptile’s is made up of several bones Mammalian fossils are often identified by the jawbone

7. Specialized Teeth Various types of teeth modified for different fx Teeth at the front of the jaw bite, cut, or hold prey Teeth along the sides of the jaw crush, grind, or slice By comparison, most reptiles’ teeth are uniformly sharp and conelike throughout the mouth

9. Ancestors of mammals  Appeared more than 300 million years ago  Amniotes (group of tetrapods that have a terrestrial adapted egg) split in 2 groups  One group gave rise to dinosaurs, birds, and modern reptiles  Other group –SYNAPSIDS-gave rise to mammals & their extinct relatives (small structure)  THERAPSIDS appeared from SYNAPSIDS and gave rise to mammals

10. Early Mammals 1 st dinosaurs and 1 st mammals appeared during the Triassic period Early mammals were about the size of mice Fossil skulls with large eye socket suggest that they were nocturnal Teeth were adapted for feeding on insects Hiding by day & specializing on insects allowed mammals to avoid threats from dinosaurs or competition w/ them Similarities in mammary tissues of several kinds of mammals suggest that milk production had evolved by the end of the Triassic period

11. Diversification of Mammals Dinosaurs dominated most terrestrial habitats while populations of small mammals continued to evolve By end of Cretaceous period (100 million years ago) 3 different types of kinds of mammals existed MODERN MAMMALS BELONG TO ONE OF THESE 3 GROUPS 1.) MONOTREMES 2.) MARSUPIALS 3.) PLACENTAL MAMMALS

12. MONOTREMES Order Monotremata Oviparous=egg laying 3 species exist today The Platypus & 2 echidna species Platypus: -waterproof fur, webbed feet, & flattened tail that aids in swimming -uses its wide, flat, leathery bill to find worms, crayfish & other inverts in soft mud Echidna: – Live in dry woodlands in Australia & New Guinea – Have protective spines, long snout, & sticky tongue to feed on ants & other insects

13. Monotremes continued Female lays 1-2 eggs encased in thin, leathery shell Incubates them with her body heat Yolk nourishes the developing embryo within the egg @ hatching, the young are very small & partially undeveloped Mother protects it and feeds it with milk from mammary glands

15. Echidnaplatypus

16. MARSUPIALS Super Order Marsupialia Divided into at least 7 orders within super order Marsupialia Majority live in Australia Virginia Opossum is the only native marsupial of the US Opossums & kangaroos & koalas Embryo develops for a short period within the mother’s uterus & then emerges from uterus & crawls into the mother’s pouch Newborn is only 2-3 cm and attaches to a nipple to feed Newborn’s development and growth then continue inside the pouch for several months

17. OpossumKoala kangaroo

18. Placental Mammals Horse, dog, rabbit, bats, monkeys, moles, mice, caribou, zebra, whales, dolphins, manatees, elephants….etc 95% of mammals are placental mammals Classified into about 20 orders

19. Give birth to well-developed young after a long period of development inside the uterus = GESTATION During development, the placenta provides nourishment & oxygen to the developing offspring Placenta begins to form shortly after fertilization, when the fertilized egg attached to the lining of the uterus Nutrients and oxygen diffuse from mother’s blood into the blood of offspring carbon dioxide and other wastes diffuse from the offspring into the mother’s blood After birth, infants feed on milk for several weeks or months

21. Average Gestation Times Opossum- 13 days Opossum- 13 days Dog- 65 days Dog- 65 days Human- 294 days Human- 294 days Giraffe- 450 days Giraffe- 450 days Sperm whale-590 Sperm whale-590 Elephant- 660 days Elephant- 660 days