Mesazoic and Cenezoic Eras

1. A View of the Earth’s
Past
Geologic History

2. Geologic History
 Geologic history recorded in layers of rocks
 Theory of Evolution
 Charles Darwin – 1859 – English naturalist (pre-
biologists)
 AKA “survival of the fittest”
 States that organisms change over time and come
from ancestral types of the same organisms
 Geologic record of fossils supports this theory

4. Geologic History
 Theory of Evolution continued
 Organisms must adapt to their environment or
else they become extinct (cease to exist on the
entire planet)
 Two types of environmental changes
1. Geologic
 Dramatic decrease in the amount of water covering
the surface
2. Climate
 Decrease in atmospheric pressure

5. Precambrian Time
 Use “time” instead of “era” because it is so long
 4.6 billion years to 570 million years ago
 88% earth’s history
 Shields – large areas of exposed Precambrian
rock
 Severely deformed from crustal activity
makes layer of rock hard to distinguish
 Half deposits of valuable minerals found in
these layers (Ni, Fe, Au, Cu)

6. Precambrian Time
 Fossils rare
 Most precambrian life thought to have soft bodies
– can’t be fossilized
 Any hard bodies destroyed by crustal movements
of subduction, volcanic activity and erosion
 Stromatolites – precambrian fossils – reeflike
depoits made from cyanobacteria
 Imprints of marine worms, jellyfish have been
found in late precambrian rocks in Austrailia

7. The Paleozoic Era
 570 million to 245 million years ago
 Beginning of era – landmasses covered with
water
 End of era – landmasses collided to form
Pangea

8. Pangea

9. The Paleozoic Era
 Abundant fossil record
 Huge increase in plant and animal life
 So much that era is divided into 7 periods

10. The Paleozoic Era: Cambrian Period
 First period of era
 Advanced marine life showed up
 Had hard parts but no backbones
 Quickly replaced precambrian organisms
 Lived in shallow seas that were abundant during
this period
 Invertebrates – animals with no backbones

12. The Paleozoic Era: Cambrian Period
 Most common: Trilobites
 Lived on ocean floor

13. Trilobite

14. The Paleozoic Era: Cambrian Period
 Second most common: Brachiopods
 15 different kinds still exist

15. Brachipods

16. The Paleozoic Era: Cambrian Period
 Other invertebrates: worms, jellyfish, snails
and sponges
 No land plants or animals found

18. The Paleozoic Era: Ordovician
Period
 Brachiopods increased
 Trilobites decreased
 Snails, clams and other mollusks became
dominant life-forms
 Coral appeared
 Graptolites – tiny invertebrates – appeared
 Useful index fossils

19. graptolites

20. The Paleozoic Era: Ordovician
Period
 Ostracoderm - First vertebrate – fish covered
with bony plates but no teeth or jaw
 Vertebrates – animals with backbones
 No plant or animal life on land

21. Ostracoderm

22. The Paleozoic Era: Silurian Period
 Marine life continued to thrive and evolve
 Echinoderms – relative of sea star – many
during this period
 Eurypterids – scorpionlike sea creatures –
abundant during this period
 Some as long as 2.4 meters found in western New
York

23. Echinoderms

24. eurypterid

25. The Paleozoic Era: Silurian Period
 First land animal such as, spiders and
millipedes, show up at the end of this period

26. The Paleozoic Era: Devonian Period
AGE OF FISHES – many kinds of bony fishes
lungfish – primitive lungs, could breathe
air
rhipidistians – also able to breathe air and
had strong fins that probably enabled them
to crawl out of water
Ichthyostega – first true amphibian
Land plants began to develop

27. lungfish

28. The Paleozoic Era:
Carboniferous Period
 Meaning “carbon bearing”
 In North America – divided into 2 sub-periods:
Mississippian and Pennsylvanian
 Warm and humid climate
 Many coal deposits in these area came from
this period

29. The Paleozoic Era:
Carboniferous Period
 Crinoids – relatives of modern sea stars
 Giant cockroaches and dragonflies
 Toward end of Pennsylvanian period – first
land vertebrates appeared
 Early reptiles resembling large lizards

30. crinoids

31. The Paleozoic Era:
Permian Period
 End of Paleozoic era – MASS EXTINCTION
 Pangea almost completely formed from
collisions of tectonic plates
 Mountains became so high that areas turned
dessert from lack of rain – inland seas evaporated
 Many marine invertebrates became extinct
 Reptiles and amphibians managed to survive this
extreme climate change

32. The Mesozoic Era
 Began 245 million years ago and ended 65
million years ago
 During this era, climate changes dramatically
 Pangea began to break up
 Shallow sea marshes covered most of the land
 Continental climates generally warm and
humid

33. The Mesozoic Era
 Called the AGE OF REPTILES because
favored the survival of reptiles
 Lizards, turtles, crocodiles, snakes, etc.

34. http://www.youtube.com/watch?v=SiN0jxZ6I2w
Fossil record – National Geographic – 3 ’ 40”

35. The Mesozoic Era:
Triassic Period
Animals
Dinosaurs first appeared during this period
“dinosaur” comes from the Greek word
meaning “terrible lizard”
Large variety of sizes
 Most in Triassic period were 4-5 m long and
moved fast

36. The Mesozoic Era:
Triassic Period
Plants
Lush forests of cone-bearing trees
 Plants that resemble todays palm trees

38. The Mesozoic Era:
Triassic Period
 Ichthyosaurs – reptiles
 Ammonite appeared – marine invertebrate
 Earliest mammals appeared – small rodent-like
forest creatures

39. ammonite

40. The Mesozoic Era:
Jurassic Period
 Dinosaurs dominated this period
 Two major types
1. Sauischians – “lizard-hipped” – herbivores
(largest called apatosaur) and carnivores
2. Ornithischians – “bird-hipped” – herbivores
(stegosaurus)

41. The Mesozoic Era:
Jurassic Period
 Pterosaur – flying reptiles – had skin over
wings
 Archaeopteryx – first true feathered birds

42. Pterosaur

43. Archaeopteryx

44. The Mesozoic Era:
Cretaceous Period
 Dinos continued to dominate Earth
 Tyrannosaurus rex - 6 m tall, huge jaws, razor
teeth
 Ankylosaurs – dinos covered with bony
armorlike plates - herbivores
 Ceratopsians – dinos with horns - herbivores
 Ornithopods – duck-billed dinos - herbivores

45.  Dinosaurs
 http://www.youtube.com/watch?v
=ywQdc_N9_Jo

46. T-rex

47. The Mesozoic Era:
Cretaceous Period
 Many plants showed up
 Angiosperms – first flowering plants
 Magnolias
 Willows
 Maples, oaks, and walnuts also showed up

48. Angiosperm flower

49. The Mesozoic Era:
Cretaceous Period
 End of period – MASS EXTINCTION
including all dinosaurs
 Theory 1: 2 mile wide meteor impacted Earth
 Theory 2: dramatic climate changes so severe
no dinos could survive

50. http://dsc.discovery.com/video-topics/other/dinosaur-
http://dsc.discovery.com/video-topics/other/dinosaur
The end of the dinosaurs – Discovery – 3’ 30”

51. The Cenozoic Era
 65 million years ago to present day
 In beginning, continents looked about same as
today
 Alps and Himalayas formed in this era
 Extreme climate changes – like ice ages
 Various species became extinct and appeared

52. The Cenozoic Era
 Called the AGE OF MAMMALS because
mammals became dominant life-forms
 Era split into two periods: Tertiary and
Quaternary
 Tertiary is divided into 5 Epochs: Paleocene,
Eocene, Oligocene, Miocene, and Pliocene
 Quaternary is divided into 2 Epochs: Pliestocene
and Holocene

53. Tertiary Period: Paleocene and
Eocene Epochs
 Many mammals evolved – small rodents and
few carnivores
 Lemuroids – first primates
 Hyracotherium – earliest ancestor of horses
 Flying squirrels, whales, and bats appeared
 Smaller reptiles increased even though dinos were
completely extinct
Climate dropped 40C worldwide

54. Lemuroids

55. Hyracotherium

56. Tertiary Period: Oligocene and
Miocene Epochs
Oligocene epoch – climate continued to cool and
get drier
Mediterranean Sea dried up – 2,000 m of
evaporites collected on sea floor
Grass and cone-bearing plants thrived in this
climate
Many earlier mammals became extinct but
some larger mammals flourished

57. Tertiary Period: Oligocene and
Miocene Epochs
Miocene Epoch – called Golden Age of
Mammals
Climate remained cool and dry
Deer, rhinoceros, and pigs
 Baluchitherium – rhinoceroslike animal – largest
known land animal ever existed (2x as large as an
elephant)
 Saber-toothed cat

58. Baluchitherium

59. Tertiary Period: Pliocene Epoch
 Hunting animals – bear, dog and cats – fully
evolved
 First modern horses
 Continental ice sheets began to spread
 Bering land bridge appears
 North and South America connect with a land
bridge

61. Tertiary Period: Pleistocene and
Holocene Epochs
Pleistocene Epoch
Several periods of glaciation occurred over
Eurasia and North America
 Animals with fur handled cold
 Other animals moved to warmer climates
 Animals that didn’t adapt, like giant sloths and dire
wolves, became extinct
 Early ancestors of modern humans found
 Hunting could have led to extinction of large mammals
like mammoths

62. Tertiary Period: Pleistocene and
Holocene Epochs
Holocene Epoch
11,000 years ago to present
Ice sheets melted
Coastlines took shape they are now
Homo sapiens – modern humans – developed
agriculture and began to make tools with bronze
and iron

63. Homo sapiens