Class Mammalia
Add to online Mammal lecture
Reference back to A&P notes beginning of
semester
Prototheria - Monotremes
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3 extant genera
all live in the Australia-New Zealand region:
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Duck-billed platypus (Ornithorhynchus)
Echidna (Tachyglossus)
Long-beaked echidna or spiny anteater (Zaglossus )
not considered ancestral to therians
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specialized surviving sidebranch
Monotremes
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lay leathery eggs (1 or 2) in underground nests
cloaca
toothless as adults
skeletal differences
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have cervical ribs
"reptilian" pelvic girdle
lack a bony housing for the ear
Monotremes
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young born very altrical
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Parental care
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platypus - young get milk by sucking/licking the belly
hair
echidna – ventral pouch for incubating and 2 suckling
regions.
Subclass Theria
Infraclass Metatheria
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Old system - Order Marsupialia
Current – several orders
Subclass Theria
Infraclass Metatheria
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Numerous during Cretaceous (end of Mesozoic)
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Southern land masses were united
During Cenozoic
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southern masses split, joined northern
Couldn’t compete with placentals.
Subclass Theria
Infraclass Metatheria
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young born tiny, very immature (altricial)
gestation short
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time in marsupium > uterus
Subclass Theria
Infraclass Metatheria
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Skeletal differences from eutherians
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shape of nasal bone
ancestral dental formulas
presence of epipubic bones
poor thermoregulators
Subclass Theria
Infraclass Eutheria
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Known from late Cretaceous
18 extant orders
Order Xenarthra (Edentata)
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most primitive
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sloths, anteaters and armadillos (protective armor)
Strong claws
adults few to 0 teeth (molars lack enamel)
Order Pholidota
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pangolins or scaly anteaters; 7 species
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tropical Africa/Asia
Scaly, epidermal layer
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curl up for protection
Order Pholidota
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pangolins or scaly anteaters; 7 species
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tropical Africa/Asia
Scaly, epidermal layer
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curl up for protection
eats ants and termites
Long tongue, strong digging feet
lack teeth
“Edentata clade”
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Order Xenarthra (Edentata)
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Armadillo and anteater
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Order Pholidota – spiny anteater
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Similarities considered convergent evolution
Stand alone groups
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Insectivora
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Carnivora
Primates
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hands that grasp
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often opposable thumb (pollex) or big toe (hallux):
well-developed sense of touch
Most have flat finger/toenails
Primates
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Enlarged brain
Stereoscopic color-vision
Many omnivorous
Most are social
Primates
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2 subdivisions
Primates
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2 subdivisions
prosimians or lower primates
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mostly small, nocturnal
Most rely on smell more than sight or sound
Lemurs, tarsiers ….
Primates
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The Anthropoids or higher primates
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Most larger, diurnal.
Apes
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no tails
Larger brain
Larger body
More upright
Fewer offspring, slower to mature
Sight more than smell
Monkeys
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nearly all have tails
Primates
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New World: all monkeys.
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Fairly small and exclusively tree dwelling.
Marmosets and tamarins,
squirrel, spider, woolly, and howler monkeys,
Old World: comprise monkeys, apes and humans.
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Bigger and spend more time on the ground.
Macaques, Baboons, Mandrills and Drills, Geladas,
Mangabeys, Guenons, Leaf-eating monkeys (Langurs, leaf
monkeys, colobus, proboscis) (Cercopithecidae)
Primates
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apes:
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Hominidae:
gorillas
 chimpanzees and bonobos (aka pygmy chimps),
 Humans
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Pongidae: orangutan
Hylobatidae: gibbons and siamang
Chiroptera
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Bats – only flying mammal
Wings – membrane between fingers
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Different from birds and pterosaurs
Chiroptera
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Bats – only flying mammal
Wings – membrane between fingers
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Different from birds and pterosaurs
Nocturnal, often forest dweller
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Eyesight poor
Well-developed echolocation
Chiroptera
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Bats – only flying mammal
Wings – membrane between fingers
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Nocturnal, often forest dweller
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Different from birds and pterosaurs
Eyesight poor
Well-developed echolocation
Related to primates?
Dermoptera
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flying lemurs or colugos (2 species)
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Squirrel size
Gliders
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Skin stretched from neck,
to forelimbs to backfeet
Related to Chiroptera?
1 clade
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Primates
Dermoptera (flying lemur)
Tree shrews
Chiroptera
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?
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Ungulata
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Order ARTIODACTYLA (even-toed ungulates eg. pigs, deer & cattle)
Order CETACEA (whales and dolphins)
Order PROBOSCIDEA (elephants)
Order SIRENIA (sea-cows)
Order HYRACOIDEA (hyraxes)
Order PERISSODACTYLA (odd-toed ungulates eg. horses, tapirs and rhinos)
Order TUBULIDENTATA (the aardvark)
“Cetartiodactyla “
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Artiodactylids and cetaceans closely related!
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Cetaceans evolved from artiodactylids
Cetartiodactyla
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Artiodactylids and cetaceans closely related!
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Cetaceans evolved from artiodactylids
Closely related to hippos, not pigs
Hippos grouped w/ pigs
Artiodactyla
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2 or 4-toed
line of symmetry passes between digits 3 & 4
Ankle structure differs from other ungulates
(greater flexibility)
pre-molars different from molars
Artiodactyla
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Suborder Suina:
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Suborder Tylopoda:
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pigs, peccaries & hippopotami:
most primitive, regrouped
camels & llamas
Suborder Ruminantia:
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cattle, antelopes, deer and giraffes: advanced artiodactyls.
Cetacea
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Suborder Odontoceti (toothed whales)
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Dolphins, killer whales, sperm whale
Suborder Mysticeti (the baleen) whales.
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Blue whale, right whales, humpback
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Proboscidea
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elephants - 2 genera, 2 species
Asian
African
Tusks normally larger,
both males & females have
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Large, communal, herbivores
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Large, communal, herbivores
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Eyes
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Small
neck not very flexible
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Smell
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Important
touch with trunk,
move to Jacobson’s organ (roof of mouth)
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Teeth
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Incisors = tusk
Molars – replaced from rear
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Teeth
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Incisors = tusk
Molars – replaced from rear
Hearing and ears
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Low frequency communication
Ears – thermoregulation
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Trunk – very sensitive (tactile)
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Respiration (snorkel for aquatic ancestor?)
Hose for water
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Trunk – very sensitive (tactile)
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Respiration (snorkel for aquatic ancestor?)
Hose for water
Chemosensory & tactile
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Trunk – very sensitive (tactile)
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Respiration (snorkel for aquatic ancestor?)
Hose for water
Chemosensory & tactile
Picking up objects
Communication – caress, threat displays, …
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Closest relative?
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Closest relative? Sirenia!
Sirenia
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sea cows, dugongs, manatees (2 genera, 5 species)
Large, slow moving herbivores
Usually solitary
Hyracoidea
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Hyraxes (3 genera, 11 species)
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Africa
rabbit size, rodent-like animals
Hyracoidea
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Hyraxes (3 genera, 11 species)
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Africa
rabbit size, rodent-like animals
4 toes in front, 3 in rear, hoof-like nails
Rubbery soles – grip rock
Hyracoidea
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Hyraxes (3 genera, 11 species)
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Africa
rabbit size, rodent-like animals
4 toes in front, 3 in rear, hoof-like nails
Rubbery soles – grip rock
Related to elephants and
sirens
Perissodactyla
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line of symmetry down third digit
a full set of incisors
greatly molarized pre-molars
Perissodactyla
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line of symmetry down third digit
a full set of incisors
greatly molarized pre-molars
2 lineages – horses vs. tapirs & rhinos
Replaced by artiodactylids
Tubulidentata
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Aardvarks – 1 species
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Nocturnal, solitary, burrower
Poor eyesight,
Hearing and smell developed
Specialize in termites
Long sticky tongue
 Strong claws and forelimbs
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digging