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Ch. 43 - Mammals
Fossils show that mammals
evolved nearly 200 million years
ago.
Age of Mammals  Cenozoic
Example of mammalian
development was the horse.
4 toes  3 toes  1 toe
Mammal Characteristics
1. Hair
2. Endothermic
4-chambered heart
Diaphragm to aid in breathing
Mainly viviparous
Mammary glands
Highly developed brain
What are some advantages of
endothermic vs. ectothermic?
 Hunt at night
 Regulate their own body temperature
 More efficient
How does hair help mammals?
 Insulation
How does the diaphragm & 4-chambered
heart help mammals?
 More efficient and higher metabolic
rates to help maintain a constant body
temperature.
Types of teeth in
mammals
1. Incisors – bite & cut
2. Canines – grip, puncture, &
tear
3. Bicuspids – shear & shred
4. Molars – grind & crush
Why are the shapes & sizes of
teeth different in mammals?
What is viviparous?
Bear live young, in which the
females care for and nourish
the young.
How do the females provide
nourishment for their young?
Mammary glands (milk)
Classification
3 main groups of mammals
 1. Placental mammals – they
nourish their young in the uterus
through the placenta.
Most mammals
 2. Monotremata – egg-laying
mammals
 3. Marsupialia – pouched mammals
Mainly in Australia
Mammal Orders
1. Monotremata
 The only order of mammals that is
oviparous (egg laying).
 Duck-billed platypus & spiny anteater
2. Marsupialia
 These mammals are born before their
development is complete. Thus, the
newborns use their front legs to pull
themselves into the mother’s pouch.
Inside the pouch are mammary glands
for them to feed on.
Placental Mammals (Orders)
What is a placenta?
 An organ that allows nutrients and
oxygen to get to the fetus through the
mother’s blood.
What is the period of development in the
mother’s uterus called?
 Gestation period
 Human’s is 9 months
 More advanced mammals have longer
gestation periods.
3. Insectivora
 Shrews, moles, & hedgehogs
 Shrews are the smallest mammals
 Mole’s fur goes both ways. Why?
4. Rodenta
 Largest mammal order
 Squirrels, chipmunks, gophers, mice,
rats, beaver
 What’s the largest rodent in N. America?
beaver
5. Lagomorpha
 Rabbits & hares
 4 upper incisors instead of 2
6. Edentata
 Means “without teeth”
 Anteaters, armadillos, & sloth
7. Chiroptera
 Bats
 Only mammals capable of true flight.
 What is echolocation?
8. Cetacea
 Whales & dolphins
 Breathe through a blowhole
9. Sirenia
 Manatees & dungongs
10. Carnivora
 Dogs, cats, raccoons, wolves, bears,
lynx, mountain lions, tigers, weasels,
ect.
 Have large canines (mainly carnivores)
11. Pinnipedia
 Sea lions, walruses, & seals
12. Perissodactyla
 Have an odd # of toes (ungulates)
 Ungulates are hoofed mammals.
 Horses, zebras, rhinos
13. Artiodactyla
 Even # or ungulates & rumen
 Deer, elk, bison, cows, moose, pigs,
sheep, giraffes, camels, antelope, ect.
14. Proboscidea
 Trunk nosed mammals
 Elephants.
15. Primates
Monkeys, apes, & humans
 Chimps
are 97.9% same genes as humans.
Human Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primate
Family: Hominidae
Genus: Homo
Specific epithet: sapien
Mammals Heart
Draw out the following parts:
R. Atrium, R. Ventricle, L.
Atrium, L. Ventricle, Vena Cava,
Tricuspid, Semilunar valves,
Lungs, bicuspid, aorta, arteries,
veins, capillaries.
What are the differences in the
vertebrate’s hearts?
2 –chambers?
Fish, larva amphibian
3-chambers?
Reptile(divided some), adult
amphibian
4-chambers?
Birds, mammals
Respiratory Systems
Fish  gills
Amphibians  gills, lungs, skin
Reptiles  lungs
Birds  lungs
Mammals  lungs & diaphragm
Nervous System
The bigger & more complex the
vertebrate the larger the brain.
All vertebrates use kidneys as
an excretory system.
Reproductive Systems
External Fertilization
Fish & Amphibians
Internal Fertilization
Reptiles, Birds, & Mammals
Oviparous  birds, some
reptiles
Oviviparous  some reptiles
Viviparous  mammals