1 / 36

Chapter 17 The History of Life

Chapter 17 The History of Life. Section 17-1 The Fossil Record. Fossils & Ancient Life. Paleontologists Scientists Who Study Fossils Infer What Past Life Looked Like What They Ate & What Ate Them Behavior Environment They Lived In. What They Looked Like. What They Ate.

laquinta
Download Presentation

Chapter 17 The History of Life

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 17The History of Life Section 17-1 The Fossil Record

  2. Fossils & Ancient Life • Paleontologists • Scientists Who Study Fossils • Infer What Past Life • Looked Like • What They Ate & What Ate Them • Behavior • Environment They Lived In

  3. What They Looked Like

  4. What They Ate

  5. Behavior & Environment 3.6 MYA

  6. Fossils & Ancient Life • Fossil Record • Organization Of Fossils From Oldest To Newest Including Supporting Information Of Other Life Forms In Their Environment

  7. Fossils & Ancient Life Key Concept The Fossil Record Provides Evidence About The History Of Life On Earth. It Also Shows How Different Groups of Organisms Have Changed Over Time.

  8. Fossils & Ancient Life • Each Fossil Is Found Only In It’s Particular Time Period or Layer • A Kind Of Fossil Clock • Of All The Life Forms That Have Ever Lived On Earth ----- • 99% Are Extinct • No Longer Alive

  9. How Fossils Are Formed • Most Form In Sedimentary Rock • Plants & Animals Die In A Water Environment And Are Covered With Silt • Others Covered With Fine Sand or Volcanic Ash • Compressed Into Rock

  10. How Fossils Are Formed • Organic Materials Are Replaced By Minerals • Quality Of Preservation Varies • Fossils Include: • Bones • Eggs • Footprints • Skin Impressions, etc.

  11. Interpreting Fossil Evidence • Fossils Are Released By • Tectonic Forces • Erosion • Mining • Construction

  12. Interpreting Fossil Evidence • Most Fossils Disarticulated • Predation • Scavengers • Rot • Catastrophic Events May Bury & Preserve Whole Animals and/or Ecosystems

  13. Life On Earth

  14. Dating Fossils Two Types of Dating • Relative Dating Organizes Fossils By Order (1st, 2nd, 3rd, etc.) Tells You Which Organisms Lived In What Order Does Not Give You Actual Years • Absolute Dating Gives You Age In Years Before Present e.g. 150 Million Years Ago

  15. Relative Dating

  16. Relative Dating

  17. Relative Dating • The Age of a Fossil Is Determined By Comparing Its Placement With Other Fossils In Other Layers Of Sedimentary Rock • Allows Comparison Of Layers World Wide

  18. Relative Dating • Index Fossils • Easily Recognized • Existed For A Short Period • Wide Geographic Distribution • Does Not Give Absolute Age

  19. Relative Dating Key Concept: Relative Dating Allows Paleontologists To Estimate A Fossils Age Compared With That Of Other Fossils

  20. Radioactive Dating Uses The Half Lives Of Certain Radioactive Isotopes In Igneous Rocks To Calculate The Age Of A Fossil Half Life The Length Of Time Required For Half Of The Radioactive Atoms In A Sample To Decay

  21. Radioactive Dating Key Concept: In Radioactive Dating, Scientists Calculate The Age Of A Sample Based On The Amount Of Remaining Radioactive Isotopes It Contains

  22. Radioactive Dating Different Radioactive Elements Have Different “tick rates” Carbon-14 Half-life = 5,730 years Decays to Nitrogen-14 Useful Back 60,000 years

  23. Geologic Time Scale Developed By Paleontologists To Classify Geologic And Biologic Events Rock Layers Fossils Present

  24. Chapter 17The History of Life Section 17- 4 Patterns of Evolution

  25. Macroevolution • Large Scale Evolutionary Changes That Take Place Over Long Periods of Time

  26. Macroevolution Key Concept: There Are Six Important Patterns of Macroevolution: • Mass Extinctions • Adaptive Radiation • Convergent Evolution • Coevolution • Punctuated Equilibrium • Developmental Gene Changes

  27. Mass Extinctions • Extinction • Occurs Constantly • 99% Earths Life Forms Extinct • Mass Extinctions • Wipe Out Ecosystems • Disrupt Energy Flow • Collapse Food Webs

  28. Mass Extinctions • Causes? • Asteroids? • Volcanic/Geologic Activity? • Effects • Habitats Left Unoccupied • Ecological Opportunity • Evolution Explosion

  29. Adaptive Radiation • Single Species or Small Group of Species Evolve Into Several Different Forms That Live In Different Ways • Darwin’s Finches • Age of Reptiles • Age of Mammals

  30. Convergent Evolution • Unrelated Species That Look And Act Remarkably Similar To Each Other But Are Not Related: • Fish - Whales • Dolphins - Sharks • Seals - Penguins

  31. Coevolution • The Process By Which Two Species Evolve In Response To Changes In Each Other • Figs & Wasp • Yucca & Bats • Orchids & Moths

  32. Punctuated Equilibrium • Evolution Is Sometimes Gradual & Slow (Gradualism, Darwin) • Horseshoe Crabs • Sharks • Cockroaches • BUT When Ecological Equilibrium Is Upset, Evolution Can Become Quite “Rapid

  33. Punctuated Equilibrium • Occurs Due To • Small Populations Become Reproductively Isolated • Mass Extinctions

  34. Punctuated Equilibrium • Brief Periods of Rapid Evolutionary Change That Interrupt Long Periods of Gradual Evolution • Still Controversial

  35. Developmental Genes & Body Plans Small Changes In Timing of Genetic Control During Embryonic Development, Make Big Changes In The Resulting Organism

  36. Click on the links below • Evolution videos: http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html • Fossil article: http://news.bbc.co.uk/2/hi/science/nature/4879672.stm • Games: http://www.abc.net.au/beasts/fossilfun/ • http://www.ucmp.berkeley.edu/education/explorations/tours/fossil/index.html • http://www.abc.net.au/beasts/fossilfun/makingfossils/default.htm

More Related