1 / 20

7-2: Evidence of Evolution

Science 7. 7-2: Evidence of Evolution. Objectives. State evidence that supports the theory of evolution Describe how fossils form. Explain what scientists learn from fossils. Forms of Evidence.

keanu
Download Presentation

7-2: Evidence of Evolution

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. Science 7 7-2: Evidence of Evolution

  2. Objectives • State evidence that supports the theory of evolution • Describe how fossils form. • Explain what scientists learn from fossils.

  3. Forms of Evidence • Similar body structures, patterns of early development, molecular structure, and fossils all provide evidence that organisms have changed over time.

  4. Similarities in Body Structure • The comparison of the structures of different organisms is called comparative anatomy. • An organism’s anatomy is its body structure.

  5. Homologous Structures • Similar structures that related species have inherited from a common ancestor are known as homologous structures.

  6. Similarities in Early Development • Scientists make inferences about evolutionary relationships by comparing how different species develop before birth. • All vertebrates have a tail and rows of tiny slits in their throats.

  7. Similarities in DNA and Proteins • If two species have similar DNA and proteins, they probably evolved from the same ancestor.

  8. How Do Fossils Form? • Fossil evidence supports the theory of evolution. • Usually only the bones or shells of animals are preserved. • Most fossils form when organisms that die become buried in sediment.

  9. Molds and Casts • Molds and casts are the most common fossil. • A mold is a hollow area in sediment in the shape of an organism or part of an organism. Forms when the bones or shell of an animal are buried in sediment.

  10. …continued… • A cast is a solid copy of the shape of an organism (opposite of a mold). Formed when an impression is preserved (footprints).

  11. Petrified Fossils • Petrified fossils are fossils in which minerals replace all or part of an organism (petrified wood or trees).

  12. Trace fossils • Trace fossils provide evidence of the activities of ancient organisms (footprints, animal burrows, grazing patterns).

  13. Preserved Remains • Some processes preserve the remains of organisms with little or no change. • Trapped in tar. • Trapped in amber. • Frozen.

  14. Learning From Fossils • Paleontologists are scientists who study fossils. • The fossil record provides evidence about the history of life and past environments on Earth. In addition. Scientists use fossils to study the rate at which evolution has occurred.

  15. History of Life • Fossils occur in a particular order. • Life began with one-celled organisms. • After a long time, plants and animals appeared.

  16. Past Environments • Fossils found in an area tell whether the area was a desert, a forest, or a freshwater swamp. • Fossils found in a area can help scientists learn about changes in Earth’s surface.

  17. Gradualism • Gradualism is a hypothesis that proposes that evolution occurs slowly but steadily. • Scientists study fossils to try to determine the rate at which evolution occurs.

  18. Punctuated Equilibria • The hypothesis of punctuated equilibriaaccounts for the gaps in the fossil record. • Most scientists today think that evolution can occur gradually at some times and more rapidly at others.

More Related