1. HISTORY OF LIFE Ch. 14

2. History of Life  Fossil Evidence of Change  Paleontologist - a scientist who studies fossils  Fossil - preserved evidence of an organism  Trace fossils - indirect evidence of organism. ex footprints, burrows, feces  Molds and Casts - impression of an organism  Replacement - original organism is replaced with mineral crystals  Petrified - Empty pore spaces are filled by minerals  Amber - Preserved tree sap hardened  Original Material - Mummification or freezing

3. Fossils  Fossil Formation - formed in sedimentary rocks

4. Dating Fossils  Relative Dating - determine the age of rocks by comparing them to those in layers around it  Law of superposition - younger layers are deposited on top of older layers, similar to stacking the daily paper on top of each other  Radiometric dating - uses the decay of radioactive isotopes of measure the age of a rock  Half-life - amount of time it takes for half of the original isotope to decay, typically use carbon 14 for dating

5. Law of Superpostion

6. Time  Geologic Time Scale - model that expresses the major geological and biological events in Earth's history, divided into precabrian and phanerozoic  Earth formed roughly 4.6 billion years ago  Era - Paleozoic, Mesozoic, and Cenozoic times  Period - smaller division of time (see diagram)

8. Earth History in a Day  If the entire history of the earth was broken down into 1 Day:  No Life from 12:01 am - 1:00 pm  Microscopic bacteria from 1:00 pm - 8:00 pm  Dinosaurs came at 10:34 pm  Humans at 11:56 pm

9. Time

10. Historic Periods  Precambrian - 90% of the earth's history, goes from the beginning of Earth's formation until 542 million years ago  Stromatolites - bacteria that produced oxygen and released it into the atmosphere, because of this Oxygen became plentiful and allowed other organisms to emerge  Paleozoic - Cambrian explosion, most major animal groups diversified, marine species moved to the land. There was a mass extinction that ended this period, 90% of the organisms disappeared

11. Historic Periods  Mesozoic - The time of the Dinosaurs, birds, and flowering plants. A meteorite struck the earth possibly causing another mass extinction  K-T boundary - the layer of rock that proves of a meteorite impact  Plate Tectonics - the movement of the plates that make up the Earth's surface  Cenozoic - The time of the Mammals, this is when humans as well as most other mammals roamed the Earth

12. Stromatolites

13. Dinosaurs  How did the dinosaurs die?

14. The Origin of Life  Spontaneous generation - idea that life arises from nonlife  ex. it was once believed that worms, insects, and fish came from mud  Theory of Biogenesis - states that only living organisms can produce other living organisms  If life can only exist from pre-existing life, then how did the first life-form appear? Which came first the chicken or the egg? Can we even figure this out? Discuss this with your partner and come write your ideas down

15. Origin of Life  Simple organic molecules - UV light from the sun, electricity from lighting, and the gases present in the atmosphere and early oceans were created through chemical reactions which produced Amino Acids, sugars, and nucleotides  Deep Sea Vents - hydro thermal vents produced sulfur, and other elements which supported a food chain for early organisms

16. Origin of Life  Meteorites - some believe that this could be the source of life  Clay - Some believe that clay was used by the Amino Acids to hold the chains of AA's together  Genetic code - RNA was life's first coding system, they can also behave like enzymes  There are still holes in this mystery, it remains unresolved

17. Origin of Life

18. Cell Theory  archea - prokaryotic cells that are restricted to volcanic and other extreme environments, get there nutrients from inorganic molecules like sulfur, they do not need or produce oxygen  Oxygen - was not present in the atmosphere until after 1.8 billion years ago  Cyanobacteria - photosynthesizing prokaryotes, formed the ozone layer, which ultimately made conditions on earth more habitable

19. Cell Theory  Endosymbiont Theory - prokaryotes lived inside of eukaryotic cells and performed cell functions just as a mitochondria or chloroplast would  These cells evolved into the modern day Eukaryotic cells

20. Cell Theory

21. Pangea

22. Review  Ch. 14 Review  p 411 - 4-8, 10  p 412 - 14,15,19  p 413 - 35-40  p 414-415 - 4,5,8,13,17