BSC2010 Unit 3 Lecture 10

What type of rock do fossils form in?

Sedimentary

Conditions in which most fossils are formed

-Sedimentary rock

-Low temperature

-Anaerobic conditions

What type of organisms are best preserved?

Aquatic organisms with hard skeletons

Principles of stratigraphy

-Younger layers deposited on top of older

-Fossils appear in the same order in different outcrops

What is used for dating sedimentary strata?

Igneous rock (contains radioisotopes)

Radiometric dating

Actual age of rock can be determined with half-life

Is the fossil record complete?

No

Plate tectonics

Shapes the position and size of the continents and influences oceanic circulation patterns, global climate, and sea level

Effects of large volcanic eruptions

-Ash and SO2 injected into the atmosphere, blocks sunlight and results in cooling

-Cooling → increased glaciation → drops in sea level → mass extinctions

First life was ____ until ___ evolved.

anaerobic; photosynthesis

Cyanobacteria formed ___

stromatolites

Precambrian Era

-4.5 bya - 542 mya

-Life consisted of microscopic prokaryotes in oceans

-Eventually, multicellular soft-bodied animals evolved

When did life first appear?

3.8 bya; precambrian era

Paleozoic era

-542-251 mya

-Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian periods

-Similar O2 concentration today

-Cambrian explosion

Cambrian explosion

Rapid diversification of life in the Paleozoic era

When did amniotes evolve?

Carboniferous period; Paleozoic era

When did Pangea form?

Permian period; Paleozoic era

What happened at the end of the Permian period?

The Great Dying

The Great Dying

96% of all multicellular species became extinct; likely due to volcanic activity; aka End-Permian Event

What may have contributed to the Great Dying/

Siberian traps → massive volcanic activity

Mesozoic era

-251-65 mya

-Triassic, Jurassic, Cretaceous periods

When did Pangea begin to break apart?

Triassic period; Mesozoic era

When did Pangea divide into Laurasia and Gondwana?

Jurassic period; Mesozoic era

What happened at the end of the Cretaceous period?

Another mass extinction → the K-T boundary

Cenozoic era

-65 mya to present

-Tertiary, quaternary periods

When did homo sapiens evolve?

Quaternary period

What is the possible sixth mass extinction called?

The Anthropocene