Kingdom AnimaliaPhylum Chordata

Subphylum VertebrataClass Mammalia

SZ2- Students will explain the evolutionary history of animals over the

geological history of Earth.

Mammals evolved from synapsid reptiles

2

Primitive Chordate

3

FishTwo Chambered Heart

4

Amphibian Heart-

3 Chambers

5

Reptilian Heart – 3 chambersCrocodile- incomplete 4

6

Fig. 48.28

7

Synapsids

•Animals with one skull opening behind eye socket•Located in the temporal region

8

Pelycosaurs

• Synapsid reptiles from Pennsylvanian and Permian – 300-245 MYA

• Body close to ground• Legs away from body• Canine like teeth

Dimetron

9

Therapsids

• Before dinosaurs• Evidence suggests

Mammals evolved from therapsids

• Body raised off the ground

• Limbs more under the body

• Teeth differentiated into 3 types

Lystrosaurus

10

Cynodonts “dog tooth”

• Lumbar ribs reduced or absent

• Well developed secondary palate

• Lower jaw reduced to one bone

Cynognathus

Thrinaxodon

11

Transitional FossilThrinaxodon

250-245 myaBody divided into lumbar and thoracic regions

12

Transitional FossilCynognathus

245-230 myaMay have been endothermic and gave birth to live youngSmaller than a wolf

13

MammalsCynodonts

Therapsids

Pelycosaurs

Canine like teeth

Limbs under body

Reduced ribs, 1 jaw bone

Molars, hair, glands

Synapsid reptiles

Cladogram of Synapsids

14

Early Mammals

• Triassic– 220 MYA

• Small• Hair• Mammary glands• Skin glands• Molar teeth

Megazostrodon

15

Repenomamus robustusAte Dinosaurs

Kingdom Animalia

Phylum Chordata

Class Mammalia1. Have fur/hair

2. mammary glands

3. Viviparous- Give birth to live young (except monotremes)

4. Length of time in uterus - gestation period

5. Extended parental care

6. 4 chambered heart

7. endothermic

1. Muscular Diaphragm

2. Specialized teeth

3. Seven cervical(neck)vertebrae

4. Outer ear

5. Well developed brain- Largest cerebrum

6. Sweat glands7. Diphyodont teeth

Two sets8. Heterodont teeth

Different shapes and functions

Mammalian Anatomical Adaptations

18

Basic Mammal

19

Lion

20

Rhinoceros

21

Gorilla

22

Chimpanzee

23

Chimp and Human

24

Bat

25

Same bones, different stance

26

27

Incissors

28

Canine

29

Premolars

30

Molars

31

Mammal Circulation

32

Fig. 31.12

33

34

Monotremes

• Lay eggs• Incubate 12 days• Lick milk from mothers

fur• Transitional species

35

Marsupials

• Pouched mammals• Birth to tiny embryo• Embryo attaches to

mother’s nipple to complete development

36

Placental Mammals

• Placenta nourishes embryo

• Long gestation period– 22 months for elephant

• Most successful group of mammals

37

Placental Mammals

• Competitive advantage over monotremes and marsupials– Better nutrition from

placenta– Less vulnerable to

predators• More advanced at birth

38

Marsupials and Monotremes in Australia

• Triassic Period– Mammals evolved– Pangea

• Jurassic Period– Monotremes and

marsupials migrated to southern pangea

• Cretaceous Period– Pangea breaks up

39

Evolution of Placenta from Amniotic EggReptile • 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

40

41

Mammal Classification

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

42

Order Monotremata

• Lays eggs• Young lick milk from

mothers fur

43

Order Marsupiallia

• Pouch•

44

Placental: Order Insectivora

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

45

Order Chiroptera• Only Flying mammals• Elongated fingers• Echolocation• Ex. batsImportance-• Seed dispersal• Pollination• Control insects

46

Echolocation

47

Smallest Mammal

• Kitti’s hog-nosed Bat• Bumble bee size• 1.5 grams

48

Order Xenarthra

• Toothless or peg like teeth

49

Order Carnivora

• Large canine teeth• Teeth adapted to shear

flesh

50

Order Rodentia

• Chisel-like incisor teeth• Continuously grow• Largest order

51

Order Cetacea

• Front limbs modified into flippers

• No hind limbs• Marine

52

Whales

• Blue whale• 100 feet long, 120 tons

– 9 story building

• Loudest animal– 188 dB• Sound travels 100’s of miles

53

54

Blue Whale

• Baleen whale• Eats krill– Tiny crustaceans– 400 pounds/day

• Heart weighs 1000 pounds– Size of a Volkswagen

• Endangered species

55

Grey Whale

56

Migrates 12,500 miles

57

Grey Whale

• 50 feet long• 35 tons• Baleen whale– Sift mud

• Endangered species

58

Killer Whale

59

Breaching

60

Killer Whale

• 12,000 pounds• Eat fish, squid, seals and

whales– 200 pounds/day

• Swim 30 mph

61

Humpback Whale

62

Order Pinnipedia

• “fin feet”• Limbs modified for

swimming• Marine carnivores• Seals, sea lions, walrus

63

Order Proboscidea

• Tusks• Largest living land

mammal

64

Order Artiodactyla

• “even toe”• Two or four toes• Giraffes, impalas,

moose, bison, cows

65

Order Perissodactyla

• “odd toed”• One or three toes• Horses • rhinos

66

Order Primates

• Opposable thumb• Binocular vision• Fingernails usually• Mammary glands

reduced to one thoracic pair

67

The End

Evolution

• Change over time• Which Chordate class do you think has more

advantages/adaptations to survive changing times?

• Which classes have disadvantages?

• Which Chordate classes can you see evolutionary similarities in so far?