"History of life on Earth"
Campbell and Reece, Chap. 25

GEOLOGICAL TIME
TRANSPARENCY (Table 25.1)
ERA, PERIOD, EPOCH
Numbers (e.g. -570-) are million years ago

(Useful to present in reverse, start at the beginning)

Precambrian 4.6 Earth
3.8 rocks
very first life 3.5 1st fossils
prokaryotes (useful to consider that bacteria cannot eat because of cell wall)
3.3 Photosynthesis -> oxygen begins 2,500

1700 (million years ago = 1.5 billion) eukaryotes

1000 1st multicellular eukaryotes

O2 high to O3

-570-

Paleozoic

Cambrian Cambrian explosion
Ancient all inv.groups
in 10 mill yr.

-510-

Ordovician 1st vertebrates,
plants to land
invertebrates
At the end, there was an mass extinction (including trilobites) probably caused by sea level fluctuations.

-439-

Silurian arthropods to land
1st vascular plants

-409-

Devonian age of many fish
first amphibian,
insects
Late there was a mass extinction possibly caused by an impact and cooling) including placoderms (extinct fish with jaws)

-363-

Carboniferous Amphibians dominate, 1st reptiles
Coal deposited before and after Carboniferous, but Carboniferous is central.
Frequently flooded swamps with vascular plantscaused "reducing" conditions.
Petroleum from microscopic organism deposits often found near deposits of foraminiferans.
(Also associated with Carboniferous but quite extensive time span.)

-290-

TRANSPARENCY (Fig. 25.3) Plate tectonics (actually not widely understood until the 1970's)
TRANSPARENCY (Fig. 25.4) Pangaea, continental drift

Permian Appalacians (large time span, Ordovician to Triassic)
Permian extinction, lose ocean habitat
Pangaea formed

-245-

Mesozoic

Triassic 1st dinosaurs
Pangaea breakup
ferns, gymnosperm forests
End of Triassic, mass extinctions, possibly global warming

-208-

Jurassic Dinosaurs, 1st birds
mammals flower plant
(Hard to imagine mammals would surpass dinosaurs, but adaptations to survival)

-145-

Cretaceous flowering plants
Rockies (started earlier, still lifting)
Mass extinctions - meteorite iridium -2.5 tril.tons 11km
TRANSPARENCY (Fig. 25.6)
TRANSPARENCY (Fig. 25.5) dramatizes mass extinctions and explosions. consider that because of human influences, we may be presently in a period of mass extinctions

- 65 million -

Cenozoic

Teritiary

Paleocene (epoch) adaptive radiation of mammals & birds
...(other epochs)...
Pliocene

-1.8-

Quarternary Pleistocene (epoch) 4 ice ages
to MO, Ohio R.
mammoths die out
first Homo

TRANSPARENCY (Fig. 16.1) review, as a phylogenetic tree

Recent (epoch) - history

Volcanic eruptions:

Francis, Self: The eruption of Krakatau, Nov 83 Sci Am
1883, 20 km3
SLIDE Krakatau

Tambora, Indonesian Island of Sumbawa, April, 1815, 150-180 km3
New England (1816) snow in June and killing frost in August
Stommel,Stommel: The year without summer, SciAm June 79

Nuclear winter:

Ehrlich et al., Long term biological consequences of nuclear war, Sci. 222, 1983, 1293-1300

Turco et al., Nuclear Winter: Global consequences of multiple nuclear explosions, Sci. 222, 1983, 1283-1292

Turco et al., The climatic effects of nuclear winter, Sci. Am. Aug., 1984, 33-43.

When combined with the prompt destruction from the nuclear blast, fires and fallout and the later enhancement of solar ultraviolet radiation due to ozone depletion long term exposure to cold, dark and radioactivity could pose a serious threat to human survivors and to other species.
ruction from the nuclear blast, fires and fallout and the later enhancement of solar ultraviolet radiation due to ozone depletion long term exposure to cold, dark and radioactivity could pose a serious threat to human survivors and to other species.

Extinctions still going on today, lots of public worry about "charismatic megavertebrates" but many other species going.

W.W. Gibbs On the termination of Species, Scientific American, November 2001, 40-49.


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