1. Mammals Chapter 34

2. What is a mammal?  Endothermic vertebrate  Amniotic egg  Four chambered heart Synapomorphies of Mammalia  Mammary glands  Hair  _____ inner ear bones  Neocortex region of brain  Single ________ bone (mandible)  Differentiated teeth  _________ dentition  Two occipital condyles

3. Anapsids, Synapsids and Diapsids Based on number of temporal openings (fenestra)  Jaw muscle attachment Anapsid: no temporal openings  Turtles Synapsid: single temporal opening  Mammals Diapsid: two temporal openings  Reptiles including birds Temporal fenestra Orbit (eye socket)

4. Evolutionary History of Mammals Mammals  First appeared ~ 225 mya  Small ________, insectivores Cynodonts  First appeared ~ 270 mya  Secondary palate Therapsids  First appeared ~ 290 mya  Limbs ________ oriented Synapsids  First appeared ~ 320 mya  Large herbivores and carnivores

5. Evolution of the Mammal Skull Synapsids  Large temporal fenestra  Differentiated teeth on single dentary bone  Hinge between quadrate and articular Therapsids  Further differentiation of teeth  Canines and incisors  Larger dentary bone Cynodonts  _______ teeth  Secondary palate  Hinge forms between dentary and squamosal  Quadrate and articular bones migrate to _______  Single lower jaw bone (dentary)

6. Mammal Dentition  Differentiation of teeth led to success in mammals  Size and arrangement of teeth associated with diet  Cusps Four distinct tooth types  Incisors: cutting  _______: tearing  Premolars: grinding  Molars: crushing, grinding

7. Diversification of Mammalian Dentition A. Hedgehog B. Mole C. Armadillo D. Anteater E. Giant Anteater F. Marmoset G. Peccary H. Bear I. Fruit-eating bat J. Nectar-eating bat K. Raccoon L. Coyote M. Mountain lion N. Horse O. Deer P. Jackrabbit Q. Woodrat R. Porpoise S. Right whale T. Walrus

8. Digestive Tracts of Carnivores and Herbivores Carnivores Herbivores  Large, expandable _________  _____ digestive tract  Large ______ with symbiotic bacteria break down plant material  _____ digestive tract

9. Modes of Locomotion Plantigrade  Most ambulatory (walking) mammals  Walk on _____ of hands and feet  Bears, primates, lagomorphs Digitigrade  Many cursorial (running) mammals  Run on one or more _____  Canids, felines Unguligrade  Ungulates  Walk or run on _____ (nails)  Horses, pigs, camels

10. Timing of Activity Diurnal: animals active during daylight  Many mammal species  Squirrels, ungulates, primates _____________: animals active during twilight hours (dawn and dusk)  Predator avoidance  Skunks, rabbits, mice, deer, bear, bobcats, coyotes Nocturnal: animals active at night  Reduce competition, escape heat, avoid predators  Highly developed senses  Large eyes (more rods, tapetum lucidum)  Large ears (greater hearing range)  Vomeronasal system  Bush babies, bats, wolves, cats, raccoons, opossums

11. Lactation Lactation: secretion of milk from mammary glands  Modified sweat glands  ________: stimulates milk production  Oxytocin: stimulates milk ________ Milk: nutritional liquid comprised of fats, proteins, and lactose  Nutrition for newborn  Transmits passive immunity  Supports growth of intestinal flora

12. Major lineages of Mammals Platypus, echidnas Marsupials Golden moles Elephant shrews Aardvarks Elephants Hyrax Manatees Armadillos, sloths, anteaters Flying lemurs Tree shrews Apes, monkeys, humans Rabbits and hares Rodents Hedgehogs, moles, true shrews Canines, felines, bears, seals, weasels Pangolins Horses, tapirs, rhinos Camels, pigs, whales, dolphins, antelope Bats Monotremes  Lack a placenta  Leathery eggs similar to reptiles  Body temp ~ 32°C Marsupials  Rudimentary, ________ placenta  Body temp ~ 35°C Eutharians  Well-developed placenta  Body temp ~ 38°C

13. Biogeography of Mammals Early Jurassic ( ~ 200 mya) Monotremes and marsupials in southern Pangaea Late Jurassic ( ~ 180 mya) Eutheria diverge from Marsupials in “South America” Early Cretaceous ( ~ 135 mya) Marsupials and monotremes isolated in “Australia” Marsupials isolated on “South America” Early Paleocene ( ~ 65 mya) Dinosaurs extinct Mammal radiation Separation of primates New world/old world Lemurs Eutheria northern distribution

14. Mammal Reproductive Tracts Monotremes Single vagina Two uteri Marsupials _____ vagina Two uteri Eutherians Single vagina Single uterus

15. Monotremes  Prototherians (“first wild beast”)  Single platypus species and four species of echidna  All found in either Australia or Papua New Guinea  Milk glands  Lack _______  Egg laying  Lack _____ as adults  Reptile like gate  Low metabolic rate  Body temp. ~32°C  Single vagina, two uteri  Cloaca

16. Marsupials  Limited to Australia and the Americas  Yolk sac placenta  High metabolic rate  Body temp. ~35°C  __________ (pouch) often present  Scrotum anterior to penis  No baculum  Females have bifurcated reproductive tract  Three vagina and two uteri  Male penis bifurcated at tip  Small braincase (relative to body size)  Minimal neocortex development  No corpus callosum We have an exam.... on Monday?!

17. Major Marsupial Orders Didelphimorphia ( ~100 species)  Opossums  New world distribution  Most semi-arboreal omnivores  ~ 50 teeth  Didactylous: unfused toes  Polyprotodont: small, unspecialized incisors Dasyuromorphia ( ~75 species)  Carnivorous marsupials (Quolls, numbats, Tasmanian devil)  Australasia  Didactylous  Polyprotodont Diprotodontia ( ~137 species)  Kangaroos, wallabies, wombats, koalas, possums  Australasia  Syndactylous: fusion of second and third digits  Diprotodont dentition: shortened mandible, enlarged lower incisors DiprotodontPolyprotodont 2 large lower incisors Multiple small lower incisors Syndactyl

18. Eutherians  Worldwide distribution  Introduced to ________  Scrotum posterior to penis  Baculum sometimes present  Female have single reproductive tract  One vagina with uterus  High metabolic rate  Body temp ~38°C  Large braincase (relative to body size)  Complex neocortex: higher functions including sensory perception, language, spatial reasoning, motor commands  Corpus callosum: connects left and right hemispheres of brain Corpus callosum Neocortex

19. Placental Mammals Placenta: organ that connects developing fetus to uterine wall and facilitated transfer of gases, nutrients and wastes. _______: outermost membrane that develops chorionic villi, which facilitates exchange between mother and fetus Umbilical cord: vascularized cord connecting fetus to placenta

20. Differences in the Placenta Marsupials  Rudimentary connection between yolk sac and maternal tissue  Large ______ provides nutrients to developing embryo  Allantois: avascular; storage of nitrogenous waste Eutherians  ____________ connects fetus to uterus  Umbilical vein and artery  Efficient exchange of nutrients, gases and waste  Reduced yolk sac  Allantois connects fetal bladder to yolk sac, which drains into umbilical cord Marsupial Eutherian Chorion Amnion Embryo Allantois Yolk Sac Maternal portion of placenta Umbilical cord Fetal portion of placenta

21. Lactation versus Gestation Times Marsupials  Dependency on yolk sac for nutrition  Young born in very immature state  Short gestation period  Prolonged lactation period Eutherians  Placenta facilitates nutrient transfer between embryo and mother  Young born in well developed state  Long gestation period  Short lactation period

22. Return to Water Three mammal clades returned to water  Cetartiodactyla  Carnivora  Afrotheria Characteristics that support terrestrial origin  Lungs and a need to breathe air from the surface  Limb bones homologous with land mammals  Vertical movement of spine  Vestigial pelvic bones in cetaceans

23. Cetacea Mysticeti Odontoceti  ______ whales  Humpback whales, blue whales, right whales, minke whales  Krill, small schooling fish  15 species  ____ blow holes  Lack echolocation  _______ whales  Sperm whales, porpoises, dolphins, killer whales  Fish, squid, marine mammals  >70 species  ____ blow hole  Echolocation

24. Cetacea Mysticeti Odontoceti Melon Brain Fat-filled cavity Tongue Baleen

25. Artiodactyla Ungulates (Hoofed Animals) Perissodactyla Peccary Camel Deer Tapir Horse 3 rd Metapodial Metapodials 3 and 4 Fused metapodials 3 and 4 Cannon bone

26. Perissodactyla Odd-toed ungulates  Equidae (Zebra, Asses and Horse)  8 species  Tapiridae (Tapirs)  4 species  Rhinocerotidae (Rhinos)  5 species  Dominant ungulates from 50 mya to 25 mya  Upper _______ present (except rhinos)  Hind gut fermentation  Large _______  Fibrous vegetation

27. Artiodactyla Even-toed ungulates  10 families, ~220 species  Pigs, hippos, camels, antelope, deer, giraffe, bovines  Radiation during Oligocene and Miocene epochs ~33 to 5 mya  Closely related to cetaceans  Cetartiodactyla  Upper incisors and canines __________ _______  Ruminant fermentation (except pigs)  “Double pulley” astragalus (ankle) bone  Greater extension and flexion Canine Deer

28. Digestion in Ungulates Ruminants Hindgut Fermenters  Artiodactyla, kangaroos  Food chewed several times  Complex, multi-chambered ________  Rate of passage ~ 80 hours  Cellulose utilization ~ __%  Perissodactyla, lagomorphs, rodents  Food chewed once  Simple stomach, large ______  Rate of passage ~ 48 hours  Cellulose utilization ~ __% Reticulum Omasum Abomasum Rumen Large intestine Cecum Small intestine Food chewed, regurgitated, then chewed again Food chewed once Large intestine Small intestine Cecum Simple stomach

29. Antlers and Horn Horns  Bovine family  Outgrowth of frontal bones  Unbranched  Covered by epidermal horny, keratinized sheath  ___________ Antlers  Deer family  Dermal bone of antler attaches to skull bone  Branched in most  Outside layer of highly vascularized skin  _______  Shed annually

30. Proboscidae  Elephants  Two genera  Elephas – Asiatic elephants  Loxodonta – African elephants  Horizontal _____ replacement Similarities to Manatees and Hyrax  Tusks derived from incisors  Flattened nails  Internal ________  Two teats near armpits  Low-frequency sounds  Long distance communication African elephant  Large ears  Three nails on hind feet  Single dome on head  Dip in back  Two lips on trunk  9 -13ft tall  8,000 - 15,400lbs Asian elephant  Small ears  Four nails on hind feet  Two humps on head  Arched back  Single lip on trunk  7-9ft tall  6,500 – 13, 200lbs

31. Sirenia  Manatees and dugongs  Three manatee and one dugong species  All four species considered threatened  Only ____________ marine mammal  Indefinite molar replacement  Found in shallow bays, estuaries, and inland river systems  Long lungs and dense bones help regulate buoyancy  Steller’s sea cow extinct 27 years after discovery by Europeans

32. Rodentia  Beaver, squirrels, mice, rats, capybara  Largest mammalian order  Worldwide distribution  Wide range of habitats  Most are small (<100g)  Single pair of upper and lower ________  Open rooted (ever growing)  Canine teeth _______  Diastema

33. Lagomorpha  Rabbits, hares, and pika  Two pairs of upper incisors  Grow constantly  Strictly herbivorous  ___________: poo eating  Large ears and hind limbs in rabbits and hares

34. Chiroptera  Bats  Second largest order of mammals  Approx. 920 species  Diverse diets  Insectivorous, carnivorous, piscivorous (fish), insectivorous, frugivorous, sanguinivorous (blood)  ___________ foraging  Diurnal roosting  Most with single litter per year  One or two young per litter Two Suborders  Megachiropterans (1 family)  Large, nectivorous and frugivorous  No echolocation  Microchiropterans (16 families)  Small, primarily insectivorous  Ecolocation

35. Primates  Lemurs, lorises, monkeys, apes, humans  Most found in tropical regions  _____ instead of claws  Clavicle  Two lower limb bones  Greater movement  Opposable thumb  Reduced snout  Reduced smell, but better vision  ____________ vision  Depth perception

36. Carnivora  Weasels, pinnepeds, cats, dogs, bears  Most are carnivores  Large brain to body mass ratio  Hunting  Camouflage fur  Ambush predators  Large canines  __________ pair  Shearing