1. 8-3 Notes – Middle and Recent Earth History
Chapter 8,
Lesson 3

2. A Changing Landscape
Most organisms that survived the Permian extinction event diversified afterwards.

3. A Changing Landscape
180 million years ago, Pangaea began to split into smaller continents.
This created a warm, wet climate for a large area.

4. Phanerozoic Eon: Mesozoic Era
The Mesozoic era is known as the “Age of Reptiles.”
Dinosaurs dominated midway through the era.

5. Phanerozoic Eon: Mesozoic Era
Toward the era’s end, land began to dry out and the largest dinosaurs became extinct.
Small mammals no larger than a possum took over as the dinosaurs went extinct. X X X

6. Phanerozoic Eon: Mesozoic Era
Invertebrates
Stromatolites increased in number after their predators became extinct at the end of the Paleozoic era.

7. Phanerozoic Eon: Mesozoic Era
Invertebrates
Insects declined in number and diversity during the Mesozoic era.

8. Phanerozoic Eon: Mesozoic Era
Invertebrates
Algae and large clams evolved.

9. Phanerozoic Eon: Mesozoic Era
Invertebrates
Reef-building corals eventually replaced large clams.

10. Phanerozoic Eon: Mesozoic Era
Vertebrates
The oceans contained predatory reptiles.
Pleiosaur
Pleiosaur
Mosasaur

11. Phanerozoic Eon: Mesozoic Era
Vertebrates
Amphibians, reptiles, and mammals that lived on land continued to evolve: frogs, turtles, crocodiles, and dinosaurs.

12. Phanerozoic Eon: Mesozoic Era
Vertebrates
Pterosaurs are flying reptiles that were different from dinosaurs, and not related to birds or bats.
Pterosaurs had hollow bones,
thin and translucent wings,
extra bones in their hands
or wings, and were probably
covered with a hairlike material.

13. Phanerozoic Eon: Mesozoic Era
Dinosaurs
The first dinosaurs were small, but new species evolved into some of the largest animals to walk the Earth.

14. Phanerozoic Eon: Mesozoic Era
Dinosaurs
It was originally thought that dinosaurs were just large reptiles, which are ectotherms.

15. Phanerozoic Eon: Mesozoic Era
Dinosaurs
Ectotherms are animals that rely on their surroundings and behavior to help them regulate their body temperature.

16. Phanerozoic Eon: Mesozoic Era
Dinosaurs
Recent evidence suggests that dinosaurs were endotherms, animals that generate internal body heat to maintain a constant body temperature.

17. Phanerozoic Eon: Mesozoic Era
Dinosaurs
Because of evidence, scientists think dinosaurs lived more like today’s mammals and birds than like reptiles.
carry tails, instead of
dragging it, and upright stance
bone cross-sections

18. Phanerozoic Eon: Mesozoic Era
Birds
Scientists believe that birds are descendents of dinosaurs.

19. Phanerozoic Eon: Mesozoic Era
Birds
Archaeopteryx, a dinosaur-like skeleton with fossilized feathers, was found in Jurassic-aged rocks.
This supports the idea that birds evolved from dinosaurs.

20. Phanerozoic Eon: Mesozoic Era

21. Phanerozoic Eon: Mesozoic Era
Mammals
Early mammals were small and not numerous for most of the Mesozoic era.
Near the end of the Mesozoic era, they began to increase in number and diversity.

22. Phanerozoic Eon: Mesozoic Era
Plants
Gymnosperms are plants that produce seeds but no flowers, and were the dominant plants of the Mesozoic era.

23. Phanerozoic Eon: Mesozoic Era
Plants
Angiosperms are flowering plants that bear seeds with hard coverings, and evolved near the end of the Mesozoic era.

24. Phanerozoic Eon: Mesozoic Era
Extinction
Smaller mass extinctions occurred at the end of the Triassic and Jurassic periods.
volcanic activity and asteroid impacts = climate change

25. Phanerozoic Eon: Mesozoic Era
Extinction
At the end of the Cretaceous period, an extinction event caused 85% of all ocean species and the remaining dinosaurs to become extinct.
Many mammal species survived.

26. Phanerozoic Eon: Cenozoic Era
The Cenozoic era is known as the “Age of Mammals.”

27. Phanerozoic Eon: Cenozoic Era
During the Cenozoic era, marine life began to recover from the Cretaceous mass extinction.

28. Phanerozoic Eon: Cenozoic Era
The offspring of organisms that survived the Cretaceous extinction make up today’s marine ecosystems.

29. Phanerozoic Eon: Cenozoic Era
Land Animals
Some mammals returned to the ocean in the early Cenozoic, and evolved into marine mammals such as whales.

30. Phanerozoic Eon: Cenozoic Era
Land Animals
Primates are animals with opposable thumbs and eyes that look forward, and they evolved during the early Cenozoic and rapidly diversified.

31. Phanerozoic Eon: Cenozoic Era
Land Animals
Hominids are animals which walk upright on two legs, and they evolved from the early primates during the Pliocene epoch, 4.4 MYA.
Humans first appeared 100,000 years ago.

32. Phanerozoic Eon: Cenozoic Era
Plants
Flowering plants have continued to evolve.
Grasses supported a large diversity of mammals, allowing mammals to multiply and diversify.

33. Complexity Increases over Time
Fossil sequences from the Archean Eon to the Cenozoic Era show that complexity increases over time.

34. Complexity Increases over Time
Life began as simple bacteria, and then became more complex and diversified as time went by.

35. Which era is known as the Age of Reptiles? A Cretaceous B Mesozoic
8.3 Middle and Recent Earth History
Which era is known as the Age of Reptiles?
A Cretaceous
B Mesozoic
C Cenozoic
D Jurassic

36. What best describes how dinosaurs are viewed today? A ectotherms
8.3 Middle and Recent Earth History
What best describes how dinosaurs are viewed today?
A ectotherms
B endotherms
C reptiles
D birds

37. During which epoch did hominids evolve? A Pliocene B Eocene C Cenozoic
8.3 Middle and Recent Earth History
During which epoch did hominids evolve?
A Pliocene
B Eocene
C Cenozoic
D Cretaceous

38. Which group declined in number and diversity during the Mesozoic era?
A stromatolites
B reef-building corals
C insects
D mammals

39. All remaining dinosaurs became extinct at the end of which period?
SCI 4.b
All remaining dinosaurs became extinct at the end of which period?
A Triassic
B Jurassic
C Cretaceous
D Mesozoic