1. Mammals
Chapter 43

2. The best mammals!

3. Origin & Evolution of Mammals
Section 43.1
Video

4. Key Characteristics: Endothermy Hair
Completely divided heart – 4 chambers
Milk – mammary glands
Single jawbone
Specialized teeth

5. Ancestors of Mammals Video 300 million years ago
Mammals are the only surviving synapsids
Distinquished by structure of the skull
First resembled modern lizard
Evolved into therapsids which evolved into early mammals
Origin of specialized teeth, endothermy, & hair
Video

6. Early Mammals Video Size of mice
Arose around the time of the dinosaurs
Not much diversity or abundance due to reign of the dinosaurs
Nocturnal
Video

7. Diversification of Mammals
Once dinosaurs went extinct mammals took over as reigning animal group
Three main types:
Monotremes: oviparous (lay eggs)
Marsupials: viviparous (live undeveloped young)
Placental mammals: viviparous (live developed young)

8. Characteristics of Mammals
Section 43.2

9. Endothermy Generate heat internally by breaking down food
Sustain activity for extended periods of time
Hair & fat help keep heat within the body
blubber

10. Circulatory System 4 chambered heart: 2 atria 2 ventricles
Septum separates right from left sides
Oxygenated & deoxygenated blood never mix
More efficient system

11. Respiratory System Adapted for efficient gas exchange
Lungs have millions of alveoli
Diaphragm: sheet of muscle below rib cage that helps draw air into the lungs

12. Feeding & Digestion Types of teeth: Adaptations for digesting plants:
Incisors:
Canines:
Premolars:
Molars:
Baleen:
Adaptations for digesting plants:
Rumen:
Cecum:

13. Nervous System Enlarged brain (15X) mostly in cerebrum
Thinking & processing center
5 major senses: smell, touch, sight, taste, & hearing
Some use echolocation to navigate
High-frequency sound waves bounce off objects

14. Development video Monotremes: Marsupials:
Lays 1 to 2 leathery shelled eggs
Undeveloped young hatches, feeds of mother’s milk to fully develop
Marsupials:
Inside mother’s womb short period of time
Newborn crawls into pouch and attaches to nipple to continue growth

15. Placental mammals: Nutrients and oxygen to fetus via placenta
Newborns are nourished via mom’s milk
Dependent upon parent for food and care

16. Mammalian Classification
Section 43.3

17. Mammalian Orders Monotremes: Marsupials: Placental: 1 order 7 orders

18. Order Monotremata Examples: platypus, spiny anteater
Only egg laying mammals
Oldest order of mammals
Only live in Australia & New Guinea

19. Video

20. Super Order Marsupialia
Examples: Kangaroo, opossum
280 different species in Australia
Only one in the US- Virginia opossum
Many species became extinct
Herbivores
Video

21. Placental Mammals
12 Orders will be in these notes!

22. Order Xenarthra Examples: anteater, armadillo, & sloth
No prominent teeth
Some with a long sticky tongues to catch prey

23. Order Lagomorpha Examples: rabbits, hares, & pikas
Double row of incisor teeth
Two large front teeth, two small back teeth
Continuously growing
Herbivores

24. Order Rodentia Examples: squirrels, chipmunks, gophers, mice, & rats
Largest mammalian order
Sharp incisors to gnaw seeds, twigs, roots & bark
Continuously growing

25. Order Primates Examples: lemurs, monkeys, gibbons, apes, & humans
Most are omnivores
Brain with large cortex allowing complex behaviors
Forward facing eyes allowing depth perception
Grasping hands and feet

26. I picked a good one!

27. Order Chiroptera Examples: bats Only truly flying mammals
Wing = modified forelimb with membrane of skin that stretches between long finger bones
Small eyes
Large ears for echolocation
Most are nocturnal

28. Order Insectivora Examples: shrews, hedgehogs, & moles
Meaning “animals that eat insects”
Small with high metabolic rate
Long, pointed noses to probe for prey
Sharp teeth
Video

29. Order Carnivora Examples: dogs, cats, raccoons,& bears
Meaning “ animals that eat meat”
Strong jaw, canine teeth, claws, and sense of smell
Pinnipeds: aquatic carnivores
Sea lions, seals, & walruses

30. Order Artiodactyla Examples: deer, cattle, giraffe, & pigs
Ungulates: mammals with hoofs
Even number of toes
Most are herbivores
Large flat molars to grind plants
Have rumen

31. Order Perissodactyla Examples: horses, zebras, rhinos, & tapirs
Ungulates with odd number of toes
Herbivores with a cecum

32. Order Cetacea Examples: whales, dolphins, and porpoises
Fish-shaped bodies with flippers
Breathe through modified nostrils
blowholes
Use echolocation
Little hair except around snout
Keep warm with blubber

33. Order Sirenia Examples: manatees & dugongs
Large, torpedo-shaped herbivores
Live in tropical seas, estuaries, & rivers
Closely related to elephants

34. Order Proboscidea Examples: elephants Proboscis: long, boneless trunk
Largest living land mammals
Tusks: modified incisors
Long gestational period (20-22 months)
Can have children up to 70 years of age!

35. Primates & Human Origins
Section 43.4

36. Primate Characteristics:
Prehensile appendages
Large cerebrum
Acute color vision
Generalist teeth
Communication
Infant care
Social organization

37. Anthropoids
Primate group that includes old & new world monkeys, apes, and humans
Adaptations:
Opposable thumb & toe (nonhuman)
Rotating shoulder & elbow joints
Great apes:
Orangutans, chimpanzees, bonobos, & humans

38. Modern Humans Only species to have bipedalism Adaptations for walking:
Tendency to walk upright on two legs
Adaptations for walking:
Bowl-shaped pelvis
S-shaped spine
Shape of foot

39. Hominids Include humans and extinct humanlike anthropoid species
All hominids were bipedial
All other anthropoids are quadrupedal (walking on four limbs)
Becoming Human Video

40. Fossil Hominids Humanlike species less than 10 myo
Much debate still between paleontologists & anthropologists

42. Hominid Species See page 878
Human evolution was NOT through a single pathway!
Earliest hominids (7-4.5 mya)
Slender australopithecines (4.5-2 mya)
Large-bodied australopithecines (2.5-1 mya)
Early humans ( mya)
Recent humans (0.5-today)
See page 878

44. Homo habilis “handy human” Fossils age between 1.6 to 2.5 million
Used tools
Larger brain capacity
Short
Stayed in Africa

45. Homo erectus “upright human”
Larger brain capacity (2/3 of modern human)
Thicker skull, large brow ridges, larger teeth
Cooked food
Traveled out of Africa

46. Homo neanderthalensis
Lived in Europe & Asia 230,000-30,000 years ago
Lived in caves
Stone tools
Heavy bones, protruding jaw, same size brain as modern human
May have interacted with Homo sapiens in some places

47. Homo sapiens Fossils found all over the world Oldest fossils in Africa
1st found in Cro-Magnon cave in France
Oldest fossils in Africa
160,000 years ago

48. Modern Humans How did we get all over the Earth?
Multiregional hypothesis
H. sapien evolved from H. erectus in local populations all over the world
Out-of-Africa hypothesis
H. sapien evolved from H. erectus ONLY in Africa and then migrated out
Supported by DNA evidence