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THE HISTORY OF LIFE SC STANDARD B-5 Students will demonstrate an understanding of the basis of evolution.

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Presentation on theme: "THE HISTORY OF LIFE SC STANDARD B-5 Students will demonstrate an understanding of the basis of evolution."— Presentation transcript:

1 THE HISTORY OF LIFE SC STANDARD B-5 Students will demonstrate an understanding of the basis of evolution

2 CN: page 54 notebook Topic: The History of Life EQ: What are the 4 important patterns of macroevolution?

3 FOSSILS Paleontologist: scientists who study fossils
Fossil Record: information about past life, including the structure of organisms, what they ate, in what environment they lived, & order in which they lived FOSSILS

4 This species lived 7700 years ago
The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, have changed over time. Extinct: term used to describe a species that has died out This species lived years ago

5 Lists of Extinct Animals
Lists of Extinct Animals

6 Formation of any fossil depends on a precise combination of conditions
How Fossils Form

7 Why is the fossil record described as an incomplete record of life’s history?
Evolution of Whales

8 Interpreting Fossil Evidence
Erosive forces cut through sedimentary rock wearing away the youngest layers first, exposing any fossils embedded in them. Interpreting Fossil Evidence

9 Paleontologists reconstruct extinct species from few fossil bits to entire bodies. They look for similarities & differences with living organisms

10 In relative dating, the age of a fossil is determined by comparing its placement in the layers of sedimentary rock Relative Dating

11 Relative Dating

12 Index fossils: distinctive fossil used to compare relative ages of fossils

13 half-life: is the length of time required for 50% of the sample of radioisotopes to decay
radioactive dating: calculating the age of a fossil based on the remaining radioactive isotopes assumption is: the amount of C-14, for example, has remained constant C-14 can only be used for fossils <60,000 yrs because of its short half-life (not enough specimen left to measure) Radioactive Dating

14 Radioactive Decay of K-40

15 Geologic Time Scale

16 Geologic evidence suggests that Earth formed over millions of years
Process began ~4.6 billion years ago This process involved multiple collisions and temperatures so high anything solid melted While melted substances arranged themselves by densities Less dense substances floated to surface and gradually cooled forming Earth’s crust Formation of Earth

17 Earth’s Early Atmosphere
Hydrogen & Nitrogen formed early atmosphere hydrogen cyanide carbon dioxide carbon monoxide sulfide water ~ 4 billion years ago Earth had cooled enough to allow 1st solid rocks to form still being bombarded by comets, asteroids, etc. too hot for water to exist in liquid form Earth’s Early Atmosphere

18 Oceans covered most of planet
~ 3.8 billion years ago Earth’s surface cooled down enough for water to stay in liquid phase Oceans covered most of planet Oceans brown due to dissolved iron Oldest sedimentary rock deposited in water

19 The 1st Organic Molecules
Miller & Urey tried to reproduce conditions on early Earth in a lab: CH4 , H2 , NH3 , H2O in a flask to represent early atmosphere passed electric shocks through it to simulate lightening Over a few days several amino acids began to accumulate Results suggests how mixtures of organic cpds necessary for life could have arisen from simpler cpds present on primitive Earth The 1st Organic Molecules

20 Proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms
Mitochondria Chloroplasts Endosymbiotic Theory

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