1. Mammals Synapsid Amniotes

2. Diapsids and Synapsids Diapsids are the line of reptiles and birds Synapsids are the mammal line –Showed up 320 mya –Lasted through Carboniferous and Permian periods –Ectotherms, some with large sails –No hair –Egg laying –Herbivores or predators

3. Emergence of Therapsids Mid-Permian period –Hindlimbs Directly under body Moved parallel to body –Trunk Ribs changed Thoracic and abdominal segments Breathe like mammals –Predatory Teeth at front for tearing Elongate jaws –Herbivores Diastema – space between front & back teeth

4. Mass extinction 240 mya –Siberian volcanic events –Diapsids had arisen –All but a few cynodonts were wiped out Became smaller Nocturnal – limited color vision in many mammals Mammal-like: hair and endothermy selected Specialized teeth

5. Another mass extinction 65 mya –Dinosaurs and many ancient birds gone –Mammals can occupy dino-niches –All modern orders by end of Tertiary period

6. Class Mammalia Hair Mammary glands Specialized teeth 3 middle ear ossicles (bones) Diaphragm Heterodont dentition Sweat, sebaceous, & scent glands 4 chambered heart Large cerebral cortex

7. Diversity of mammals 5,400 species Bumblebee bat 3-4 cm to Blue whale 30 m

8. Subclass Prototheria Includes Infraclass Ornithodelphia, “bird birthplace”, the monotremes –Cloaca –Oviparous (egg laying) –Controversial category

9. Subclass Theria Infraclass Metatheria –Marsupials –Viviparous w/short gestation time –Protective pouches –250 species in Australia and the Americas

10. Subclass Theria Infraclass Eutheria –Placental mammals –Born at advanced stage of development –Exchanges across placenta –Over 4,000 species, 17 orders (see table 22.1, and others throughout chapter)

11. Evolutionary pressures Terrestrial on all continents but Antarctica Live in all oceans Many adaptations over following slides

12. Skin Epidermal and dermal layers Protects against –Mechanical injury –Microorganisms –UV rays Important in –Temp regulation –Sensory perception –Excretion –H 2 O regulation

13. Hair Unique to mammals Keratinized product of epidermis Sits in hair follicle Pelage – hair covering –Long protective hairs –Dense, short underlayer

14. Hair and molting Hair = dead skin cells, must be molted –Some occurs gradually –Some have winter/summer coats Thickness Color (arctic fox)

15. Hair and touch Displacement of hair stimulates nerves Especially legs, arms, mouth, eyes Guard hairs – vibrissae

16. Hair defense Air spaces provide insulation Arrector pili, smooth muscle around hair –Makes hair stand up –When threatened –Animal looks larger & tougher

17. Hair color How much melanin? Dark on top Light on bottom Aposematic colors – skunk

18. Reduced pelage Hot climates Aquatic animals Naked mole rats

19. Claws Present in all amniotes Keratin over ends of digits Can be nails or hooves

20. Glands Sebaceous (oil) glands – lubricate and waterproof Sudoriferous (sweat) glands –Evaporative cooling –Salt, urea, water (stank) Scent or musk glands –Defense –Species/mate recognition –Territorial behavior

21. Mammary glands Functional in females Present/nonfunctional in males Secrete milk (water, carbs, fat, protein, minerals, antibodies) Monotremes excrete milk into “belly bowls”

22. Skull Reptiles – jaw articulates at 2 small bones Mammals –Bones have moved to middle ear –Jaw articulates at lower jaw bone

23. Sophisticated palate Hard palate at roof of mouth developed 2x –In archosaurs –In therapsids In mammals, 2ndary palate further separates mouth & nasal passages Breathe while chewing Stop to swallow

24. Teeth Reptiles – homodont or all the same Mammals –heterodont with different functions –Set in sockets –2 sets –Four kinds Incisors Canines Premolars molars

25. Specialized dentition Reduced dentition – armadillos & anteaters Omnivorous lives Grinding herbivores Gnawing rodents –Diastema –Eat close to ground Tearing carnivores

26. Vertebral column Five regions –2 cervical vertebrae – atlas and axis Giraffe and whale both have 7 neck vertebrae Tree sloth has 6 or 9 cervical vertebrae –Thoracic region Ribs Freedom of motion –Lumbar region - support

27. Legs & hips Appendages under body Move along anteroposterior plane Bones of pelvic girdle fused –Advantage for locomotion –Disadvantage for birthing

28. Muscles Skeleton supports weight Muscles concentrated in upper appendages Running animals have less muscle in lower legs

29. Feeding Digestive tract similar to other vertebrates Specialized for varied feeding –Order Carnivora – carnivores or omnivores –Insectivores – eat arthropods and soft inverts –Herbivores – eat plants & inverts on plants

30. Digestion Rodents have a fermentation pouch or cecum –between small & large intestine –Aids digestion of cellulose Ruminants – sheep, cattle, and deer –4 chambered stomach –1 st 3 are fermentation chambers –Microorganisms make cellulose digesting enzymes –Cud

31. Circulation Bird & mammal hearts – convergent evolution Placental Exchange –Maternal and fetal blood never mix –Nutrients, gases, and wastes exchange –Fetal lungs inflated at birth

32. Gas Exchange High metabolic rates need efficient gas exchange Long snouts warm & moisten air Lungs like sponges

33. Gas Exchange Inspire w/negative pressure –Contract diaphragm –Expand chest Expire 2 ways –Elastic recoil –Contraction of thoracic & abdominal muscles

34. Thermoregulation Shivering thermogenesis little movement Lots of heat Non-shivering thermogenesis Cellular metabolism Metabolism of brown fat

35. Making heat Insulated w/pelage No pelage –Lower surface temperature –Walruses –Appendages w/fur Too much heat –dissipate Too cold –Tuck in appendages –Conserve heat

36. Other systems Cooler veins are warmed by nearby arteries Evaporative cooling Big ears dissipate heat

37. Winter sleep vs. hibernation Winter sleep –Retreat to burrows –Slow down, but easily roused –Bears and raccoons Hibernation –Monotremes, rodents, bats –Body temp, respiration, heart rate, metabolism all drop –May lose 1/3 – 1/2 of body weight

38. Nervous system Integrated systems move to brain –Sense of touch – hair follicles –Olfaction – smell food, peers, predators –Auditory senses 3 middle ear ossicles High sensitivity to pitch –Vision Overall weak color vision Squirrel, primates, & some others see color

39. Excretion Mammals excrete urea –Less toxic than ammonia –Requires some water Urine thicker than blood –2x in beavers –22x in Australian hopping mice

40. Water loss Depends on activity, physiological state, temperature Lost in urine, feces, sweat, nursing Kangaroo rat does not drink –Dry feces –Low protein diet –Metabolism makes water

41. Behavior Varied –Cat with arched back –Dog wagging tail –Wolf on its back

42. Smell and Behavior Pheromones Recognize parents and young Breed Urinate on self Skunks

43. Herd behavior Stay calm if familiar sounds continue –Bleating –Breaking twigs –Stomach rumblings

44. Tactile communication Primates –Nosing –Grooming Keeps pelage clean Reinforces social relationships

45. Territoriality Mammals mark territory –Your cat isn’t nice –This is not cute  –Sea lions

46. Reproduction Viviparity –Requires energy –Not tied to a nest –Uterus modified to nourish fetus –Care for young

47. Cycles Beneficial time to reproduce –Temperature –Rainfall –Available food All subject to cycles

48. Cycles Estrus cycle –Behaviorally and physiologically keen to mate –Release of mature ova Monestrus, diestrus, polyestrus Delays –Delayed fertilization – bats –Embryonic diapause

49. Development Monotremes –Oviparous –Shell glands deposit shell –Incubate eggs in ventral pouch –Lay eggs in burrow

50. Pre-placental mammals Marsupials –Uterine milk –Vascular yolk sac – early placenta –8 – 40 day gestation –Another 60 – 270 days in pouch

51. Placental mammals Eutherian mammals –Placenta - embryonic & uterine tissue –Gestation 20 days to 19 months –Altricial - helpless newborn –Precocial – walk and run quicklywalk and run quickly