Notes on the geologic & life history of Earth from Precambrian to the present Cenozoic Era

1. Prehistory 1:
Geologic
Time
ppt. by Robin D. Seamon
Resource: TEXTBOOK:
Prentice Hall Earth Science
notes
http://home.earthlink.net/~tran
qbase/images/fossils.jpg

2. HIGHLIGHTS:
• Earth: 4.5 billion years old
• ¾ of the geologic timeline holds life
• Life forms changed Earth’s chemistry
• Catastrophes affected the evolution of life-
extinctions
• New weedy species thrives & takes over after
an extinction
VIDEO: How Much is A Million?

3. Geologic Time Scale
Geologic
Timeline in
Excel
LINK
Neogene
Paleogene

4. EXTINCTIONS: widespread & rapid decreases in
amount of life on Earth.
5 major Extinctions:
65
mya
K-Pg Extinction 75% extinct
(killed
dinosaurs)
Mammals &
birds survive
200
mya
Triassic-Jurassic
extinction event
75% extinct Dinos & birds
survive
251
mya
Permian-Triassic
extinction event
95% life extinct
“Great Dying”
Archosaurs
survive
375
mya
Devonian
extinction
70% extinct Marine life
changed
450
mya
Ordovician-
Silurian extinction
70% extinct X 2 2 events

6. Mass extinctions:
• Long-term stress compounded by short-term
shock (2 things)
POSSIBLE CAUSES
• Flood basalt events (LIP)
• Sea level falls
• Impact events (asteroid/comet)
• Sustained & significant global cooling
• Sustained & significant global warming
• Anoxic events: (lack of O in oceans-warming)
• Oceanic overturn (disruption of thermohaline
circulation)

7. • Plate tectonics
• Initiate/end Ice Ages
• Change ocean & wind patterns
• Close off or open land bridges
• Decrease continental shelf
• Arid interior
• OTHER:
• New disease
• Out-competition
• Man-made extinction of species

8. EFFECTS & RECOVERY
• Weedy species- species that can quickly adapt
to the environment; becomes dominate
• Reproduce quickly
• Disperse widely
• Live in a variety of habitats
• Establish populations in strange places
• Resist eradication once established
• 5-10 million years before re-diversification

9. Geologic Timeline CALENDAR LAB
If Earth’s whole history was
compressed into 1 year, each
day would represent 12.5
million years.
According to this calendar,
animals & plants didn’t
evolve on Earth until the
late Fall.
First fish started crawling
onto land, evolving into
amphibious creatures with
legs in early December
Primates (group that today
contains lemurs, monkeys,
humans) only appeared in
the last week of December.

11. PH1 UNIT CHECK1
1. Age of the Earth according to geologists
2. How many major extinctions has Earth experienced?
3. How long does it take for biological re-diversification to
happen on Earth?
4-5. Name two supercontinents that were once on the Earth.
6. What is the species that is able to withstand the
environmental changes and resulting mass extinctions? They
repopulate Earth.
A- Mesozoic Era
B- Paleozoic Era
C- Cenozoic Era
D- Precambrian
1. Era in which we live
2. Era in which dinosaurs were dominant
3. Era in which fish and marine animals
were dominant
4. Earliest time period- only bacteria
4.5 billion years old
5
5-10 million years
Rodinia, Pangaea
Weedy species
C
A
B
D

12. Precambrian Era: Vast and Puzzling
 4.5 Billion years ago to the Cambrian Period
 3.4 bya: microscopic bacteria
 Atmosphere: water vapor, CO2 , Nitrogen,
NO OXYGEN
 Ozone layer protects from UV: water protects
 Later, primary plants evolved, used
photosynthesis which created oxygen
 Oxygen accumulates 2.5 bya

13. Precambrian Era: Vast and Puzzling
 Fossils:
* stromatolites: layered mounds and columns of
calcium carbonate (material deposited by algae)
* 600 mya 1st multi-celled animals
 EXTINCTION

14. Remnants of Precambrian Rocks

15.  After Precambrian Era, time is divided into 3
other eras:
* Paleozoic Era
(Invertebrates Fish Amphibians)
* Mesozoic Era
* Cenozoic Era

16. Early Paleozoic Era: Life Evolves
 540 mya
 Divided into 6 time periods:
* Cambrian Period
* Ordovician Period
* Silurian Period
* Devonian Period
* Carboniferous Period
* Permian Period
 Paleozoic Era
 LIFE EVOLVES
early life began in the seas
shells, trilobites

17. Early Paleozoic Era: Life Evolves
Land masses:
* First: Gondwana ( S. Amer, Africa, Australia,
Antarctica, Asia) MAP
*Then another mass is raised: Laurasia
(N. Amer, Eurasia) MAP
* Then in Permian Period, there was: Pangaea
(all continents together) MAP
ADVANCE

18. BACK

19. Cambrian Period: “Age of Invertebrates”
first organisms with shells, trilobites dominate
Ordovician Period: first fish
Silurian Period: “Age of Fishes”
first land plants
Devonian Period:
fish dominate, first insect fossils
Carboniferous Period: “Age of Amphibians”
amphibians abundant, large coal swamps,
Permian Period: extinction trilobites & other marine
animals; first reptiles
Periods of the Paleozoic Era
ppt LINK
ppt LINK
ppt LINK

20. Late Paleozoic Era
 At the end of the Paleozoic Era, (400mya)
plants adapted to water’s edge to inland
 Amphibians diversified
 Greatest of 5 mass extinctions
(Climate became seasonal)
ADVANCE

21. Silurian Period
BACK

22. BACK
Ordovician Period

23. Armor-Plated Fish
BACK

24. Model of a Pennsylvanian
Coal Swamp
BACK

25. Permian Period Reptiles
ADVANCE

26. Mesozoic Era: “Age of Reptiles”
 350 mya
 Divided into 3 time periods:
* Triassic Period
* Jurassic Period
* Cretaceous Period
 Dinosaurs were land-dwelling reptiles that
were dominate during Mesozoic Era
 Major event: breakup of Pangea

27. Mesozoic Era: “Age of Reptiles”
 Life:
* gymnosperms
* Canadian Rockies formed
* shelled egg: adaptation favoring land birth
IMPORTANT EVOLUTIONARY STEP
* Reptiles dominate
ADVANCE

28. BACK

29. The Flying Reptile Pteranodon
ADVANCE

30. Fossil Skull of an Extinct Crocodile

31. Periods of the Mesozoic Era
Triassic Period “Age of Reptiles”
Dinosaurs dominate
Jurassic Period
First birds, dinosaurs dominate
Cretaceous Period
First angiosperms (flowering plants)
ADVANCE

32. Jurassic Period
BACK

33. Cretaceous Period

34. MASS EXTINCTION!!!
K-Pg Boundary- Earth struck by 6-mile wide asteroid,
resulting in mass extinction: 65 mya
End of the Mesozoic Era:
Badlands, SD

35. Cenozoic Era: “Age of Mammals”
 65 mya
 Considered the “Age of Mammals”
 Divided into three periods
* Paleogene Period
* Neogene Period
* Quaternary Period
 Plate movement led to much mountain building,
volcanism, earthquakes

36. Cenozoic Era: “Age of Mammals”
 Angiosperms replace gymnosperms as
dominate land plants
 Mammals (animals that bear live young,
maintain steady body temperature) replace
reptiles as dominate animal
 adaptations such as insulating body hair, more
efficient heart & lungs, allow mammals to lead
more active lives

37. Fossils from La Brea Tar Pits

38. Cenozoic Era: “Age of Mammals”
 Life
Large mammals & extinction:
* In N. America, mastodon & mammoth
(huge relatives of elephant), saber-toothed cats,
giant beavers, large ground sloths, horses,
camels, giant bison become extinct
???? WHY???

39. Cenozoic Era: “Age of Mammals”
Mastadon
Wooly mammoth

40. Cenozoic Era: “Age of Mammals”
Saber-toothed tiger
Giant ground sloth

41. Cenozoic Era: Human Ancestors
2 mya – 10mya humans?

42. PH1 UNIT CHECK1

43. Reader’s Theater:
North American History
Character
LINK
Script
LINK

44. LAB:
Geologic Beaded
Timeline

45. LAB Activity:
Group Timeline Project
Precambrian Paleozoic Mesozoic Cenozoic
Cambrian
Your timeline should include in pictures and words the following: (use
color)
Time ( - )
Era _____________, “Age of _________” Period
Geology
Atmosphere & weather
*New adaptations
plants, animals
Extinctions?

46. COMPUTER LAB Activity:
Geologic Timeline in Excel
LINK

47. RESOURCE:
TEXTBOOK: Prentice Hall Earth Science
notes 6th grade