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

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

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)

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

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

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

INFRACLASS ORNITHODELPHIA Monotremes – egg-laying mammals embryos develop for 10-12 day in uterus leathery shell is secretes around embryo eggs hatch in 10-14 days young obtain milk from mother, but no nipples are present Include: duck-billed platypus, echidnas (spiny anteater)

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

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

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

Virginia opossum …

Tasmanian devil (l) & numbat (r)

Bandicoot …

Koala …

Sugar glider …

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

Red Kangaroo …

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)

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

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

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

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

Bats … Evening bat

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

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

Primates … Spider monkey

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

Nine-banded armadillo Yes, road kill

Three-toed sloth …

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

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

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

Mice and rats …

Beaver …

Squirrels …

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

Gray wolf …

Red fox …

Brown bear …

Cheetah …

Tigers …

Raccoon …

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

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

Horses …

Burchell’s (Plains) Zebra …

Rhinoceros …

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

Cows & goats …

Whitetail deer …

Hippopotamus …   26-JUN-2005 Joey Chan

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

Dolphin … Porpoises lack distinct beak

Humpback whale …