1. PHYLUM CHORDATA SUBPHYLUM VERTEBRATA A SURVEY OF DIVERSITY
BIO 122: Zoology
Part 3
Mammals

2. CLASS MAMMALIA Mammals Dermal covering of hair on most
internal fertilization & development
4-chambered heart

3. CLASS MAMMALIA Additional characteristics:
integument with sweat, scent & mammary glands
diphyodont teeth (milk & permanent)
movable eyelids & fleshy ears
endothermic (heat from own metabolism)
homeothermic (maintain body temperature = warm blooded)

4. CLASS MAMMALIA Dermal coverings (all have a hair or it's derivative):
Pelage (fur) a) dense & short hair - for insulation (can be shed) b) coarse longer hair - for protection & coloration
Vibrissae (whiskers) - sensory hairs
Nails, claws & hooves - very dense on appendage tips

5. CLASS MAMMALIA Variation of appendages: tetrapods terrestrial - 4 legs
aquatic with modified to fins
bats with webbings on front appendages – wings
2 legs & 2 arms - can walk erect

6. CLASS MAMMALIA Reproductive patterns: 3 Infraclasses
Monotremes duck-billed platypus & echidna egg-laying, hatch early & feed off mothers milk
Marsupials kangaroo, opossum short development in uterus, birth, long lactation
Placentals cat, dog, human long development in uterus, birth, short lactation

7. INFRACLASS ORNITHODELPHIA
Monotremes – egg-laying mammals
embryos develop for day in uterus
leathery shell is secretes around embryo
eggs hatch in days
young obtain milk from mother, but no nipples are present
Include: duck-billed platypus, echidnas (spiny anteater)

8. INFRACLASS ORNITHODELPHIA
Duck-billed platypus (l), Echidna (r)

9. INFRACLASS METATHERIA
Marsupials – pouched mammals
the developing embryos do not implant in the uterus
cause development of shallow depressions in uterine wall
absorb nutrients through a vascularized yolk sac
gestation (time in uterus) is short
followed by a prolonged development in a sac where they lactate for a long time

10. INFRACLASS METATHERIA
Marsupials: Numerous animals in this group, including four orders.
opossums (80+ species) – Americas
marsupial mice – Australia & Tasmania
bandicoots – Australia & Tasmania
koalas, wallabies, kangaroos – Australia to East Indies

11. Virginia opossum …

12. Tasmanian devil (l) & numbat (r)

13. Bandicoot …

14. Koala …

15. Sugar glider …

16. Wallaby (l) & Kangaroo (r)
Wallaby is smaller

17. Red Kangaroo …

18. INFRACLASS EUTHERIA Placentals - viviparous mammals
embryos do implant in uterus for a prolonged period
a placenta develops for embryo attachment in the uterus
gestation time varies (from 21 days in rabbits to 22 months in elephants)

19. INFRACLASS EUTHERIA
The Placentals have been divided into a number of Orders based on:
Skull and snout shape
Dental formula (incisors, canines, premolars and molars)
Limbs (size & shape)
Number digits on appendages
Claws, nails on appendages

20. ORDERS OF PLACENTALS Shrews and moles small body elongate snout
limbs pentadactyl
teeth primitive (not very complex)

21. Shrews and moles … Shrews – long tail, visible ears, small feet
Moles – short tail, obscure ears, large front feet

22. ORDERS OF PLACENTALS Bats Wings with limb bones greatly elongated
claws on only first two digits of front limbs
hind legs pentadactyl
use of echolocation

23. Bats …
Evening bat

24. Bats …
Rafinesque’s Bat (l) Eastern Red Bat (r)

25. ORDERS OF PLACENTALS Primates (lemurs, monkeys & humans)
enlarged cerebral hemispheres
limbs with ball & socket articulation
pentadactyl digits (opposable thumb)

26. Primates …
Spider monkey

27. ORDERS OF PLACENTALS Edentates (anteaters, armadillos & sloths)
At least some front claws enlarged (for digging or hanging)
teeth reduced (peg-like) or absent

28. Nine-banded armadillo
Yes, road kill

29. Three-toed sloth …

30. ORDERS OF PLACENTALS Rabbits & hares tail short or vestigial
ears medium to large
4 upper incisors (front teeth for biting)

31. Rabbits …
Cottontail (l) & swamp rabbit (r) - notice ear size

32. ORDERS OF PLACENTALS Rodents (mice, rats, beavers, squirrels)
2 upper incisors which permanently grow
canine teeth missing

33. Mice and rats …

34. Beaver …

35. Squirrels …

36. ORDERS OF PLACENTALS Carnivores (dogs, wolves, fox, bears, raccoons)
at least four clawed toes on each foot
incisors small, canines large

37. Gray wolf …

38. Red fox …

39. Brown bear …

40. Cheetah …

41. Tigers …

42. Raccoon …

43. ORDERS OF PLACENTALS Elephants long trunk (proboscis) ears very large
long incisors (tusks)

44. ORDERS OF PLACENTALS Perissodactyls (horses, zebras, rhinoceros)
foot ending on third digit (hooves)
odd-toed mammals
head elongate
ears moderate & tubular

45. Horses …

46. Burchell’s (Plains) Zebra …

47. Rhinoceros …

48. ORDERS OF PLACENTALS Artiodacytls (cows, goats, deer, hippos)
Hooves (commonly 2)
even-toed mammals
upper incisors reduced

49. Cows & goats …

50. Whitetail deer …

51. Hippopotamus …
26-JUN-2005
Joey Chan

52. ORDERS OF PLACENTALS Dolphins, porpoises & whales
aquatic with fins (hind appendages lacking)
skin essentially lacking hair
external ears lacking
blowhole

53. Dolphin …
Porpoises lack distinct beak

54. Humpback whale …