1. Chapter 14 The History of Life

2. Section 14.1 The Record of Life

3. Early History of Earth
-The Earth is billion years old
-Life originated in Earth’s oceans
between billion years ago

4. History in Rocks Fossils—Clues to the past A fossil
(化石) is evidence of an organism that lived long ago

5. History in Rocks Fossil formation （P 371）
For fossils to form, organisms usually have to be
buried in mud, sand, or clay soon after they die.
These particles are compressed over time and
harden into a type of rock called sedimentary rock
(沉积岩).

6. History in Rocks Trace fossil-
Foot prints, nests/dens, or fossilized feces (poop)
Tell scientists about the activities going on at that time

7. History in Rocks
Mold-
Organism dies in soft mold and leaves an imprint of it’s body

8. History in Rocks
Cast-
Starts as a mold, but over time a mixture of water and minerals fill in the mold
Makes a 3D model of the organism

9. History in Rocks Petrified/ Permineralized fossil-
Minerals invade and replace organism’s parts as it dies
Makes very detailed skeletons
Body is turned to stone

10. History in Rocks Amber-preserved fossil
-Organism lands on a tree and gets stuck in the tree sap
-Over time the sap changes to Amber stone
-Organism is often perfectly preserved

11. History in Rocks Relative dating (相对定年法)
As layers of sediment rock build on top of each other, the fossils in the deepest layers of rock most be older than those above them.
General age of fossil, cannot be exact

12. History in Rocks Radiometric dating (放射性定年法 )
Using radioactive isotopes to age fossils
Carbon-14
Potassium-40
Chlorine-36

13. A Trip Through Geologic Time
The geologic time scale
- The Precambrian (前寒武纪)
- The Paleozoic Era(古生代)
- The Mesozoic Era(中生代)
- The Cenozoic Era(新生代)
Each era(代) is subdivided into periods(纪)
Geological Calendar:
All of Time in just 1 year!
Formation of the Earth is
00:00 on 1/1

14. A Trip Through Geologic Time
The Precambrian Era
4570 – 542 million year ago
Life Begins
Prokaryotes form
Eukaryotes form
Invertebrates appear
-complex organisms
with no backbones
Geological Calendar:
2/25- 11/18

15. A Trip Through Geologic Time
Life during the Precambrian
Unicellular prokaryote appear
( million years ago)

16. A Trip Through Geologic Time
Life during the Precambrian
More complex eukaryotic organism appeared (2500 – 2100 million years ago)

17. A Trip Through Geologic Time
Life during the Precambrian
Multicellular eukaryotes, such as sponges and jellyfishes, and invertebrates diversified and filled the oceans (543 million years ago)

18. A Trip Through Geologic Time
The Paleozoic Era:
million years ago
First Vertebrates
First Fish
First Land Plants
First Amphibians
First Reptiles
First Trees
Geological Calendar:
11/18- 12/12

19. A Trip Through Geologic Time
Cambrian explosion (寒武纪大爆发，
535 to 525 million years ago)
Dramatic increase in number of species

20. Permian extinction (二叠纪大灭绝)
“The Great Dying”
-End of the Paleozoic Era
96% of Marine species
70% of vertebrates
83% of Insect species
-Caused by climate
change
-Hotter temperatures
-volcano activity
-Ice Age
-Dust reflects sunlight

21. A Trip Through Geologic Time
The Mesozoic Era:
million years ago
First dinosaurs
First mammals
First flowers
First birds
Geological Calendar:
12/12 – 12/26

22. Mesozoic Mass Extinction:
Second largest extinction
Caused by an asteroid impact and increased volcanic activity
Known as the K-T Extinction

23. Continental Drift
（板块漂移）
Movement of tectonic plates

24. A Trip Through Geologic Time
The Cenozoic Era:
65 million years ago – Present day
-Domination of
mammals
-Evolution of
Humans
-Modern Society
Geological Calendar:
12/26 – 12/31

25. Geological Time Line Homework:
Create your own representation of the Geological Time
- Work in Groups of 2 or 3
- Must show the ratio used
- Must show all events listed on p.376
- Creative designs can get bonus points
- You will present your time line next class
- MiniLab 14.2 on p.376 will help you;
You do not have to follow MiniLab 14.2!!
SHARE the work!

26. P 390

29. Section 14.2 The Origin of Life

30. Origins: The Early Ideas
Spontaneous generation
The idea that nonliving material can produce life

31. Origins: The Early Ideas
Spontaneous generation is disproved by Francesco Redi:
Maggots only grow on meat exposed to flies
What about microbes?
There are bacteria everywhere?! How they must appear from a life force in the air…

32. Origins: The Early Ideas
Louis Pasteur:
French Scientist
One of the creators of Microbiology and did experiments that supported Germ Theory
Germs cause disease
Germs do not spontaneous generate
Biogenesis (生源论)
The idea that living organisms come only from other living organisms

33. Origins: The Modern Ideas
Simple organic molecules formed
In the 1930s, a Russian scientist, Alexander Oparin, hypothesized that life began in the oceans that formed on early Earth.

34. Origins: The Modern Ideas
Simple organic molecules formed
In 1953, two American scientists, Stanley Miller and Harold Urey, tested Oparin’s hypothesis by simulating the conditions of early Earth in the laboratory.

35. Origins: The Modern Ideas
The formation of protocells
A protocell(原细胞) is a large, ordered structure, enclosed by a membrane, that carries out some life activities, such as growth and division.

36. Early Life Forms Archaebacteria:
First forms of complex life; Can only survive in extreme environments
Used abundant organic molecules for food
Evolved to produce glucose through chemo-synthesis

37. Origins: The Modern Ideas
Photosynthesizing prokaryotes

38. Origins: The Modern Ideas
Death By Oxygen!
Most species up to this point were anaerobic prokaryotes
Creation of an oxygen rich atmosphere changed environment
Dramatic shift in microbe evolution

39. Origins: The Modern Ideas
The Endosymbiont theory(内共生理论)
Eukaryotes evolved through a symbiotic relationship between ancient prokaryotes.

40. Origins: The Modern Ideas
Experimental evidence shows:
Chloroplasts/Mitochondria contain DNA that is similar to the DNA in prokaryotes
Chloroplasts/Mitochondria have their own ribosomes
Chloroplasts/Mitochondria reproduce independently

43. That’s all