MAKING AT IMELINE OF LIFE ON EARTH

							MAKING A TIMELINE OF LIFE ON EARTH                         Name: ____________________________
                                                           Period: ____
BACKGROUND:
               About 4.6 Billion Years Ago (BYA), the Earth was a ball of molten rock. As the surface cooled, a rocky
      crust formed and water vapor in the atmosphere condensed to form rain. By 3.9 BYA, oceans covered much of
      the earth’s surface. Rocks formed in these oceans contain fossils of bacterial cells that lived about 3.5 BYA. The
      fossil record shows a progression of life-forms and contains evidence of many changes in Earth’s surface and
      atmosphere.
               In this lab, you will make a timeline showing the major events in Earth’s history and in the history of Life
      on Earth, such as the evolution of new groups of organisms and the mass extinctions. This timeline can be used
      to study how living things have changed over time.
MATERIALS:
      Cash Register Tape                         5 meters
      Meter Stick and/or Metric Ruler
      Colored Pens & Pencils
STEP 1:
      1.  Cut off a 5 meter length of cash register tape.
         a. 5 meters has been marked off with blue tape on the floor, use them as a guide to cut your tape.
      2. 10-15 cm from one end of the tape, draw a dark line across the tape and Label that line “TODAY”
      3. Draw a Bold/Dark line across the tape every meter. Each meter = 1 Billion Years
         a. Mark each line with the time marks e.g. 1 BYA, 2 BYA, 3 BYA, 4 BYA and stop
STEP 2:
      4.  Start at “TODAY” and make a lighter line every 20 cm
         a. At this end write your legend “20 cm = 200 million years”
                    i. 200 Million years also equals 0.2 Billion Years
                   ii. 200 Million years also equals 1 hour on the timeline clock you will need to answer the questions
                       on the back
                           1. The “Today” line = Midnight (12 am)
                           2. Label each 20 cm line moving back in time from Midnight. The first 20 cm line will be
                                11pm, the next is 10pm, etc. moving back in time all the way to the 4.6 BYA mark
      5. Go 4.6 BYA mark and label your tape: EARTH WAS FORMED
STEP 3:
      6.  Go to the “TODAY” end of the tape – Using a meter stick or ruler with a metric scale, mark the Era’s and
          Periods. Remember, each millimeter = 1 million years:
         a. On the one edge/side of the tape, Mark a band of color for each “ERA”
         b. On the other edge/side of the tape, Mark a band of color for each “PERIOD”
         c. Label the Precambrian Eon on the Era side, and Precambrian Era'
      7. Research how long ago each of events below occurred: (visit the NOVA Interactive Timeline. Find this and
          other links on the Biology website). Mark each event and label it.
                       Evidence of Life
                       Photosynthetic Bacteria (Cyanobacteria)
                       Atmospheric Oxygen reaches 3%
                       Evidence of Bacteria on Land first appears in the fossil record
                       Mass Extinctions, Mark and label the BIG 5 (List on the website) (use “Δ” to mark each extinction)
                       Evidence of Endosymbiosis (from textbook)
                       First Eukaryotes first appear in the fossil record
                       True-Algae Fossils first appear in the fossil record
                       Soft Bodied Animals first appear in the fossil record
                       Chordates first appear in the fossil record
                       Vascular Land plants first appear in the fossil record
                       Fish appear in the fossil record
                       Land Arthropods first appear in the fossil record
                       Land Vertebrates first appear in the fossil record
                       Seed Plants first appear in the fossil record
                       First Reptiles appear in the fossil record
                       Dinosaurs first appear in the fossil record
                       Mammals first appear in the fossil record
                       Birds first appear in the fossil record
                       Flowering Plants first appear in the fossil record
                       Primates first appear in the fossil record
                       Hominids first appear in the fossil record
                       Modern Humans first appear in the fossil record
ANALYSIS:
     If you have marked your tape properly, you will have 24 segments going back from “TODAY”
     (“12:00 am”) to the 4.6 BYA mark (“12:00 am the day before”). Remember: each 20 cm mark is
     1 hour (representing 200 million years) in a 24 hour day.

      To answer the questions below, count the hours back from “TODAY” (12:00 am), 20cm=11pm,
      40cm=10 pm, 60cm=9 pm, etc.

1. How long has life existed on Earth? Ans. Since _______o’clock, AM or PM

2. Only unicellular life forms existed between which hours? ____ - ____, AM or PM

3. At which hour did the multicellular life appear on Earth? _____ hr _____ min., AM or PM

4. At which hour did the first land plants appear on Earth? _____ hr _____ min., AM or PM

5. At which hour did the first land insects appear on Earth? _____ hr _____ min., AM or PM

6. At which hour did the first land animals appear on Earth? _____ hr _____ min., AM or PM

7. At which hour did the first land reptiles appear on Earth? _____ hr _____ min., AM or PM

8. At which hour did the first mammals appear on Earth? _____ hr _____ min. , AM or PM

9. At which hour did the Genus Homo first appear on Earth? _____ hr _____ min. , AM or PM


10. How are the mass extinctions related to the appearance of new major groups of organisms?




11. Cyanobacterium are thought to be responsible for the first free oxygen in the Earth’s atmosphere.

   a. Did they both appear at the same time?     Circle:   Yes   or    No

   b. If “No”, why not?



12. What percentage of time has life existed since Earth formed? _____._____ %


13. What percentage of time has our species, Homo sapiens, existed since Earth formed?

                                 _____._____ %