Class Mammalia

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Class Mammalia
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Key Characteristics of Class Mammalia

• 1 Body covered with hair/fur, but
• reduced in some
• 2 Integument w/ sweat, scent,
• sebaceous glands
• 3 Young nourished by milk from mammary
• glands (only active in females)
• 4 Complex individual and social behavior

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• 5. Muscular diaphragm
• 6. Anucleated biconcave red blood cells

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• 7 Mouth w/ diphyodont teeth (milk, or
• deciduous teeth replaced by a permanent set)
  
• teeth heterodont in most lower jaw a single
• enlarged bone (dentary)
• 8 Movable eyelids and fleshy external ears
• (pinnae)
• 9 Four limbs (reduced or absent in some)
• adapted for many forms of locomotion
• 10 Circulatory system of a 4 chambered heart,
• nonnucleated, biconcave red blood cells.
• 11 Respiratory system of lungs w/ alveoli and
  
• voice box

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• 12 Endothermic/Homesostasis
• 13 Cloaca present only in monotremes
• (shallow in marsupials)
• 14 Separate sexes sex determination by
• males (heterogametic)
• 15 Internal fertilization eggs develop in
• uterus w/ placental attachment
• (placenta rudimentary in marsupials
• and absent in monotremes)
• 16 Brain highly developed

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Highly Evolved Brain

• The large neocortex has granted mammals with a
  well-developed memory capacity to learn rapidly
  and to respond appropriately to problems not
  previously encountered.
• Highly elaborated sense organs, and special
  senses, particularly those of hearing, smell, and
  touch, contribute an inflow of environmental
  information that provide mammals with a level of
  awareness and responsiveness unequaled in the
  animal kingdom.

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• Class Mammalia
• Subclass Prototheria (extinct mammals)
• Subclass Theria (modern mammals)
• Infraclass Ornithodelphia (monotremes)
• Infraclass Metatheria (Marsupials)
• Infraclass Eutheria (placentals)

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MONOTREMES
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Monotremes

• There are only three living monotremes (not
  diverse.)
• Duck-billed platypus
• Two species of echidna, or "spiny anteaters"
• All of them are found only in Australia and New
  Guinea.

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Monotremes

• Lay leathery eggs (1 or 2) in
• underground nests
• Toothless as adults
• Young born very altricial

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Bird, Reptile, or Mammal ?

• In some ways, monotremes are very primitive for
  mammals because, like reptiles and birds, they
  lay eggs rather than having live birth.
• (oviparous, cloaca, altricial)
• In a number of other respects, monotremes are
  rather derived, having highly modified snouts or
  beaks, and modern adult monotremes have no teeth.
  
• Like other mammals, however, monotremes have a
  single bone in their lower jaw, three inner ear
  bones, high metabolic rates, hair, and they
  produce milk to nourish the young.

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Spiny Echidna
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A mother platypus cares for her immature young.
The babies are not fully formed when they hatch
-- lacking hair, claws, and a sense of sight.
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Infraclass Metatheria
Marsupials
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Marsupials

• Give birth at a very early stage of the embryos
  development and nourish the newborn by milk
  instead of by a placenta.
• Australia, South America, and North
• America
• Inhabit a variety of habitat, from rainforest to
  desert

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Baby Marsupials

• Offspring are born in an almost embryonic state
  after a very short gestation.
• The newborn makes its way to one of the mothers
  nipples, were it remains attached for several
  weeks.

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• Opossums (only native US)

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Placentals

• In placental mammals the placenta allows
  developing young to obtain nourishment and grow
  in a protected environment during the most
  vulnerable period of their lives.
• After birth the young continue to feed by
  suckling from Mammary Glands.
• A long period of parental care and education
  allows the young to acquire necessary survival
  skills.

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Carnivora, Insectivora, Rodentia

• Order Carnivora
• Cats, dogs, bears, skunk, badger,
• Well developed canine teeth
• All carnivorous?
• Order Insectivora
• Hedgehogs, shrews, moles (not voles)
• Canine teeth same size as cheek teeth
• Order Rodentia
• Rats, beaver, voles, gophers
• Eat grain
• Large incisor, no canine

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Order Lagomorpha

• Rabbits, hares

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• Young very tiny
• Born premature
• Less investment

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Order Xenarthra (Edentata)

• most primitive
• sloths, anteaters and armadillos (protective
  armor)
• Strong claws
• adults few to 0 teeth (molars lack enamel)

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Order Pholidota

• pangolins or scaly anteaters 7 species
• tropical Africa/Asia
• Scaly, epidermal layer
• curl up for protection
• eats ants and termites
• Long tongue, strong digging feet
• lack teeth

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Edentata clade

• Order Xenarthra (Edentata)
• Armadillo and anteater
• Order Pholidota spiny anteater
• Similarities considered convergent evolution

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Stand alone groups

• Insectivora
• Carnivora

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Primates

• Hands that grasp
• often opposable thumb (pollex) or big toe
  (hallux)
• Well-developed sense of touch
• Most have flat finger/toenails

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Primates

• Enlarged brain
• Stereoscopic color-vision
• Many omnivorous
• Most are social

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Primates

• 2 subdivisions

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Primates

• 2 subdivisions
• prosimians or lower primates
• mostly small, nocturnal
• Most rely on smell more than sight or sound
• Lemurs, tarsiers .

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Primates

• The Anthropoids or higher primates
• Most larger, diurnal.
• Apes
• no tails
• Larger brain
• Larger body
• More upright
• Fewer offspring, slower to mature
• Sight more than smell
• Monkeys
• nearly all have tails

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Primates

• New World all monkeys.
• Fairly small and exclusively tree dwelling.
• Marmosets and tamarins,
• squirrel, spider, woolly, and howler monkeys,
• Old World comprise monkeys, apes and humans.
• 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)

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Primates

• apes
• Hominidae
• gorillas
• chimpanzees and bonobos (aka pygmy chimps),
• Humans
• Pongidae orangutan
• Hylobatidae gibbons and siamang

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Chiroptera

• Bats only flying mammal
• Wings membrane between fingers
• Different from birds and pterosaurs
• Nocturnal, often forest dweller
• Eyesight poor
• Well-developed echolocation

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Dermoptera

• flying lemurs or colugos (2 species)
• Squirrel size
• Gliders
• Skin stretched from neck,
• to forelimbs to backfeet

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Cetartiodactyla

• Artiodactylids and cetaceans closely related!
• Cetaceans evolved from artiodactylids
• Closely related to hippos, not pigs
• Hippos grouped w/ pigs

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Artiodactyla

• 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

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Artiodactyla

• Suborder Suina
• pigs, peccaries hippopotami
• most primitive, regrouped
• Suborder Tylopoda
• camels llamas
• Suborder Ruminantia
• cattle, antelopes, deer and giraffes advanced
  artiodactyls.

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Order Perissodactyla

• Odd toed (1-3)
• Horse, rhino, tapir

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Perissodactyla

• line of symmetry down third digit
• a full set of incisors
• greatly molarized pre-molars
• 2 lineages horses vs. tapirs rhinos
• Replaced by artiodactylids

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Perissodactyla

• line of symmetry down third digit
• a full set of incisors
• greatly molarized pre-molars

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Cetacea

• Suborder Odontoceti (toothed whales)
• Dolphins, killer whales, sperm whale
• Suborder Mysticeti (the baleen) whales.
• Blue whale, right whales, humpback

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• Proboscidea
• 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
• Eyes
• Small
• neck not very flexible

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• Smell
• Important
• touch with trunk,
• move to Jacobsons organ (roof of mouth)

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• Teeth
• Incisors tusk
• Molars replaced from rear

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• Teeth
• Incisors tusk
• Molars replaced from rear
• Hearing and ears
• Low frequency communication
• Ears thermoregulation

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• Trunk very sensitive (tactile)
• 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!

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Sirenia

• sea cows, dugongs, manatees (2 genera, 5
  species)
• Large, slow moving herbivores
• Usually solitary

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Hyracoidea

• Hyraxes (3 genera, 11 species)
• 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

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Tubulidentata

• Aardvarks 1 species
• Nocturnal, solitary, burrower
• Poor eyesight,
• Hearing and smell developed
• Specialize in termites
• Long sticky tongue
• Strong claws and forelimbs
• digging