This History of Life

Questions to ponder

Where did we come from?

How did the Earth created or come to be?

Theories Big Bang theory Creation

Big Bang Theory Big Bang - The Big Bang Theory is

the dominant scientific theory about the origin of the universe. According to the big bang, the universe was created sometime between 10 billion and 20 billion years ago from a cosmic explosion that hurled matter and in all directions

Creationism Divine origin - (Earth

and life was not spontaneous and placed here by creator)

Earth 4.6 billion years old (radiometric

dating) Current population 7,206,766,000 261 born every minute Year 1000 = 310 million (current US

pop.) 1900 = 1.6 billion 2050 = 9 billion Life first appeared on Earth between

3.9 – 3.5 billion years ago.

Birth of Earth Earth was one big ball of magma Meteorites hit the Earth causing heat Volcanoes emit gases creating

atmosphere (H20, CO2, S02, CO, H2S, HCN, N2, H2)

http://www.youtube.com/watch?v=Tz8ithgTBj4

Clues in rocks Earth cooled and water formed oceans 500 millions of years ago, life first

appeared Earliest clues date 3.5 billion years ago Records in fossils: Trace, Molds/Casts,

Replacement, Petrified, Amber, Original material)

Pangea In 1915, a geologist named Alfred Wagner

came up the theory of Continental drift. This theory states that parts of the Earth's crust slowly drift atop a liquid core. Fossils records found, support  the theory of continental drift and plate tectonics. Pangea started as one big super continent then during the Jurassic period broke up into two smaller super continents.

Pangea

Geological Time Scale Model that expresses the major

geological and biological events in Earth’s history.

Divided into Precambrian and Phanerozoic eon.

Era – next largest division Period – each era divided into one or

more periods

Dinosaurs What happened to them? Theories:

› Volcanism› Plate tectonics (earthquakes)› Disease› Alvarez Asteroid Theory (The asteroid hit the

Earth. Research found a likely candidate for the crater at Chicxulub, on the Yucatan Peninsula of Mexico.)

› http://www.youtube.com/watch?v=Y8Ij9xboreA

Mass Extinction 1. End Ordovician (~445 Ma); ~12% of families, ~ 65%

species; large glaciation/sea level fall?? 2. Late Devonian (~365 Ma); ~ 14% of families, ~ 72%

species; impact (Siljan Crater)? 3. End Permian (~250 Ma); ~ 52 % families, >90%

species; impact (Bedout Crater)?; flood basalts (Siberia); one continent; global warming; low oxygen conditions

4. End Triassic (~210 Ma); ~ 12% families, ~ 65% species; impact (Manicouagan Crater); flood basalts (Central Atlantic)

5. End Cretaceous (65 Ma); ~11% families, ~ 62% species; impact (Chixculub