Class Mammalia

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Class Mammalia
BIO 2215 Oklahoma City Community College Dennis
Anderson
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Class Mammalia

• Hair
• Mammary glands
• Sweat glands
• Diphyodont teeth
• Two sets
• Heterodont teeth
• Different shapes and functions

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Class Mammalia

• Movable eyelids
• Two occipital condyles
• Three ear bones
• Muscular diaphragm
• Placenta
• Except two groups
• Endothermic
• Four chambered heart

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Fig. 48.28
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Synapsids
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Pelycosaurs

• Synapsid reptiles from Pennsylvanian and Permian
• 300-245 MYA
• Body close to ground
• Legs away from body
• Canine like teeth

Dimetron
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Therapsids

• Body raised off the ground
• Limbs more under the body
• Teeth differentiated into 3 types
• Secondary palate developing
• Phalangeal formula develops 2-3-3-3-3

Lystosaurus
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Cynodonts

• Lumbar ribs reduced or absent
• Well developed secondary palate
• Lower jaw reduced to one bone

Thrinaxodon
Cynognathus
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Transitional FossilCynognathus
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Transitional FossilThrinaxodon
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Early Mammals

• Triassic
• 220 MYA
• Small
• Hair
• Mammary glands
• Skin glands
• Molar teeth

Megazostrodon
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Repenomamus robustusAte Dinosaurs
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Cladogram of Synapsids
Cynodonts
Mammals
Therapsids
Pelycosaurs
Synapsid reptiles
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Basic Mammal
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Lion
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Rhinoceros
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Gorilla
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Chimpanzee
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Chimp and Human
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Bat
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Same bones, different stance
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Incissors
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Canine
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Premolars
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Molars
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Evolution of Blood Circulation
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Primitive Chordate
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FishTwo Chambered Heart
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Fish Circulation
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Fig. 31.11
Amphibian Heart
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Amphibian Circulation
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Fig. 31.12
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Mammal Circulation
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Bats

• Only flying mammal
• Seed dispersal
• Pollination
• Control insects

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Echolocation
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Smallest Mammal

• Kittis hog-nosed Bat
• Bumble size
• 1.5 grams

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Whales

• Blue whale
• 100 feet long, 120 tons
• 9 story building
• Loudest animal 188 dB
• Sound travels 100s of miles

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Blue Whale

• Baleen whale
• Eats krill
• Tiny crustaceans
• 400 pounds/day
• Heart weighs 1000 pounds
• Size of a Volkswagen
• Endangered species

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Grey Whale
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Migrates 12,500 miles
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Grey Whale

• 50 feet long
• 35 tons
• Baleen whale
• Sift mud
• Endangered species

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Killer Whale
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Breaching
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Killer Whale

• 12,000 pounds
• Eat fish, squid, seals and whales
• 200 pounds/day
• Swim 30 mph

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Humpback Whale
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Monotremes

• Lay eggs
• Incubate 12 days
• Lick milk from mothers fur
• Transitional species

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Marsupials

• Pouched mammals
• Birth to tiny embryo
• Embryo attaches to mothers nipple to complete
  development

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Placental Mammals

• Placenta nourishes embryo
• Long gestation period
• 22 months for elephant
• Most successful group of mammals

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Placental Mammals

• Competitive advantage over monotremes and
  marsupials
• Better nutrition from placenta
• Less vulnerable to predators
• More advanced at birth

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Marsupials and Monotremes in Australia

• Triassic Period
• Mammals evolved
• Pangea
• Jurassic Period
• Monotremes and marsupials migrated to southern
  pangea
• Cretaceous Period
• Pangea breaks up

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Evolution of Placenta from Amniotic Egg

• Reptile
• Chorion
• Oxygen from air
• Amnion
• Provides private pond
• Yolk Sac
• Food for embryo
• Allantois
• Store urinary waste

• Mammal
• Chorion
• Form placenta to get oxygen food from mothers
  blood
• Amnion
• Provides private pond
• Yolk sac
• Temporarily make RBCs
• Allantois
• Form umbilical cord

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Mammal Classification

• 14 major orders
• Over 4,000 species
• About half are rodents

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Order Monotremata

• Lays eggs
• Young lick milk from mothers fur

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Order Marsupiallia

• Pouch

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Order Insectivora

• Sharp-snout
• Small
• Burrow underground
• Eat insects

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Order Chiroptera

• Flying mammals
• Elongated fingers
• Echolocation

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Order Xenarthra

• Toothless or peg like teeth

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Order Carnivora

• Large canine teeth
• Teeth adapted to shear flesh

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Order Rodentia

• Chisel-like incisor teeth

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Order Lagomorpha

• Four upper incisors
• Hind legs adapted for jumping

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Order Cetacea

• Front limbs modified into flippers
• No hind limbs
• Marine

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Order Pinnipedia

• Limbs modified for swimming
• Marine carnivores

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Order Proboscidea

• Tusks
• Largest living land mammal

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Order Artiodactyla

• Two or four toes

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Order Perissodactyla

• One or three toes

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Order Primates

• Opposable thumb
• Binocular vision
• Fingernails usually
• Mammary glands reduced to one thoracic pair

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The End