Presentation is loading. Please wait.

Presentation is loading. Please wait.

End Show Slide 1 of 40 Copyright Pearson Prentice Hall Outine 17-1: The Fossil Record.

Similar presentations


Presentation on theme: "End Show Slide 1 of 40 Copyright Pearson Prentice Hall Outine 17-1: The Fossil Record."— Presentation transcript:

1 End Show Slide 1 of 40 Copyright Pearson Prentice Hall Outine 17-1: The Fossil Record

2 End Show Slide 2 of The Fossil Record Copyright Pearson Prentice Hall Fossils and Ancient Life I. Fossils and Ancient Life A. Paleontologists are scientists who collect and study fossils. B. Fossil record. 1. Includes information about: a. structure of organisms b. what they ate c. what ate them d. what environment they lived in e. sequence of organisms from past f. how organisms change over time

3 End Show Slide 3 of The Fossil Record Copyright Pearson Prentice Hall Fossils and Ancient Life C. Fossil record provides incomplete information. 1. Over 99% of all species that have lived on Earth have become extinct.

4 End Show Slide 4 of The Fossil Record Copyright Pearson Prentice Hall How Fossils Form II. How Fossils Form A. Most fossils form in sedimentary rock. 1. Erosion causes existing rock to break into small particles of sand, silt, and clay. 2. These particles fall to bottom of lakes, rivers, or the ocean. 3. Then sediments pile up in layers over time

5 End Show Slide 5 of The Fossil Record Copyright Pearson Prentice Hall How Fossils Form Fossil Formation Water carries small rock particles to lakes and seas.

6 End Show Slide 6 of The Fossil Record Copyright Pearson Prentice Hall How Fossils Form Dead organisms are buried by layers of sediment, which forms new rock.

7 End Show Slide 7 of The Fossil Record Copyright Pearson Prentice Hall How Fossils Form The preserved remains may be later discovered and studied.

8 End Show Slide 8 of The Fossil Record Copyright Pearson Prentice Hall Interpreting Fossil Evidence III. Dating Fossil Evidence A. Paleontologists determine age of fossils using relative dating or radioactive dating. B. Relative Dating 1. Look at placement of fossils within the layers of rock a. Oldest layers at bottom b. More recent layers on top 2. Can estimate a fossils age compared to other fossils & rock layers

9 End Show Slide 9 of The Fossil Record Copyright Pearson Prentice Hall Interpreting Fossil Evidence Relative Dating

10 End Show Slide 10 of The Fossil Record Copyright Pearson Prentice Hall Interpreting Fossil Evidence C. Radioactive Dating 1. Used to assign an absolute age to rocks. 2. Some elements are radioactive and steadily break down into nonradioactive elements. They are said to decay. 3. Uses the half-lives of radioactive elements to determine the age of a rock or fossil a. Half-life is the length of time required for half of the radioactive atoms in a sample to decay.

11 End Show Slide 11 of The Fossil Record Copyright Pearson Prentice Hall Interpreting Fossil Evidence

12 End Show Slide 12 of The Fossil Record Copyright Pearson Prentice Hall Interpreting Fossil Evidence 4. Scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains compared to non- radioactive elements. a. They have tables of ratios that they can compare their data to get a more absolute age for the fossil. Compare amount of C-14 to C-12

13 End Show Slide 13 of The Fossil Record Copyright Pearson Prentice Hall Interpreting Fossil Evidence 5. Examples of radioisotopes: a. Carbon-14 Changes into N-14 as it decays Half-life is 5,730 years Useful for dating fossils less than 50,000 years old b. Potassium-40 Changes into Ar-40 & Ca-40 Half-life is 1.3 billion years c. Uranium-238 Half-life is 4.5 billion years

14 End Show Slide 14 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale IV. Geologic Time Scale A. First developed by studying rock layers and fossils worldwide. Later assigned dates with radioactive dating. B. Geologic time is divided into Eras. 1. Oldest to youngest: Precambrian, Paleozoic, Mesozoic, Cenozoic C. Eras are divided into Periods. 1. Mesozoic Era divided into: Triassic, Jurassic, Cretaceous

15 End Show Slide 15 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale D. Geologic time begins with Precambrian Time, which covers about 88% of Earths history. Vendian650–544 DONT COPY THE TABLES!

16 End Show Slide 16 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale E. The Paleozoic began about 544 million years ago. 1. Many vertebrates and invertebrates lived during this time.

17 End Show Slide 17 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale Permian Carboniferous Devonian Silurian Ordovician Cambrian 290– – – – – –505

18 End Show Slide 18 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale F. The Mesozoic began about 245 million years ago. 1. Dinosaurs lived during this time. 2. Mammals began to evolve during this era.

19 End Show Slide 19 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale Cretaceous Jurassic Triassic 145–65 208– –208

20 End Show Slide 20 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale G. The Cenozoic began about 65 million years ago and continues to the present. 1. Mammals became common during the Cenozoic.

21 End Show Slide 21 of The Fossil Record Copyright Pearson Prentice Hall Geologic Time Scale

22 End Show 17-1 The Fossil Record Slide 22 of 40 Copyright Pearson Prentice Hall Geologic Time Scale Clock Model of Earths History First humans First prokaryotes Cenozoic Era Mesozoic Era Paleozoic Era Precambrian Time First land plants First multicellular organisms First eukaryotes Radiation of mammals Accumulation of atmospheric oxygen

23 End Show - or - Continue to: Click to Launch: Slide 23 of 40 Copyright Pearson Prentice Hall 17-1

24 End Show Slide 24 of 40 Copyright Pearson Prentice Hall 17-1 Which of the following statements about fossils is NOT true? a.Most fossils form in sedimentary rock. b.Fossils occur in a particular order. c.Only a small portion of fossils are from extinct organisms. d.Fossils can be used in relative dating of rock formations.

25 End Show Slide 25 of 40 Copyright Pearson Prentice Hall 17-1 The fossil record consistently shows evidence that a.all forms of life have existed in all geologic eras. b.living organisms have only been on Earth for a short time. c.living things have changed over time. d.ancient life-forms are much the same as forms found living today.

26 End Show Slide 26 of 40 Copyright Pearson Prentice Hall 17-1 Index fossils assist paleontologists in dating rocks because they represent species that a.were widely distributed and existed for a very long time. b.existed in a single location for a short period of time. c.were widely distributed and existed for a short time. d.existed in a single location for a very long time.

27 End Show Slide 27 of 40 Copyright Pearson Prentice Hall 17-1 Determining the age of a fossil by comparing its placement with fossils in other layers of rock is called a.carbon-14 dating. b.fossil-indexing. c.relative dating. d.absolute dating.

28 End Show Slide 28 of 40 Copyright Pearson Prentice Hall 17-1 According to the geologic time scale, geologic time begins with a.Precambrian Time. b.the Paleozoic Era. c.the Quaternary Period. d.the Cambrian Era.


Download ppt "End Show Slide 1 of 40 Copyright Pearson Prentice Hall Outine 17-1: The Fossil Record."

Similar presentations


Ads by Google