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The Missing Piece: A Tale of a Tail
What to Know
Teaching Time
Two 50-Minute Sessions
Grade Level
Middle School
  • Reading, Writing, Speaking and Listening
  • History
  • Science and Technology
Historical Period
  • Expansion and Reform - 1801-1855
  • Civil War and Reconstruction - 1856-1876
Famous for fossil and dinosaur discoveries, paleontologists Edward Drinker Cope and Othneil Marsh became the talk of the 1860s-1870s as they rivaled over the misplacement of the head of "Elasmosaurus platyurus Cope". Cope placed the head of the marine reptile on its tail. Was it a careless mistake or was a key piece missing from the puzzle? Paleontologist, Joseph Leidy, proved the misplacement to be true and Marsh eagerly informed the public of his former colleague's mistake. In this lesson students will have the opportunity to study primary source images of the skeletons and illustrations of Elasmosaurus platyurus Cope, as well as documents written by Cope and Leidy. The final objective of the lesson is for students to answer the question, "Which end is the tail?" This answer will be obtained by analyzing primary sources independently and cooperatively. In a history class, this lesson can be used as an introduction into a specific history topic in which the truth or facts were difficult to find as a result of missing information or items.


1.Examine symbols/illustrations of historians and scientists on a concept map in order to identify their field of study. 2.Use the experience of the group puzzle activity to explain how the works of historians, paleontologists, and other scientific experts are similar to a puzzle. 3.Analyze a photo of Joseph Leidy and a dinosaur bone to determine the field of expertise that is shown (e.g. historian, scientist, paleontologist, etc.) 4.Discuss some of the challenges a paleontologist might face in his/her job. 5.Compare and contrast two skeleton diagrams and illustrations of the Elasmosaurus platyurus Cope. 6.Explore the physical characteristics of the Elasmosaurus platyurus Cope to identify how it lives. 7.Analyze and evaluate the two skeleton diagrams and illustrations of the Elasmosaurus platyurus Cope, as well as written documents by Cope and Leidy to answer a series of questions about the Elasmosaurus platyurus Cope problem. 8.Based upon a group analysis and discussion of diagrams, illustrations, and written documents, formulate an answer to the question, "Which end is the tail?" 9.Write an article for a historical or scientific magazine defending an answer to the question, "Which end is the tail?" Students should support their answer with detail, site examples from appropriate sources, and provide personal reflections. 10.Based upon your study of the problem faced by Edward Cope and Elasmosaurus platyurus Cope, synthesize the challenges faced by historians and other experts as they attempt to uncover the truth about people, places, things and events that occurred in the past.

Standards Alignment

  • History

    8.1.9. B. Analyze and interpret historical sources.
    8.1.9. D. Analyze and interpret historical research using primary sources.
    8.2.9. B. Identify and analyze primary documents, material artifacts and historic sites important in Pennsylvania history from 1787 to 1914.
    8.3.9. B. Identify and analyze primary documents, material artifacts and historic sites important in United States history from 1787 to 1914.

  • Reading, Writing, Speaking, and Listening

    1.1.8. D. Identify basic facts and ideas in text using specific strategies.
    1.1.8.G. Demonstrate after reading understanding and interpretation of both fiction and nonfiction text, including public documents.
    1.2.8.A. Read and understand essential content of informational texts and documents in all academic areas.
    1.4.8. B. Write multi-paragraph informational pieces.
    1.4.8. C. Write persuasive pieces.
    1.5.8. A. Write with a sharp, distinct focus.
    1.5.8. C. Write with controlled and/or subtle organization.
    1.5.8. E. Revise writing after rethinking logic of organization and rechecking central idea, content, paragraph development, level of detail, style, tone, and word choice.
    1.5.8. F. Edit writing using the conventions of language.
    1.5.8.B. Write using well-developed content appropriate for the topic.
    1.6.8. D. Contribute to discussions.
    1.6.8. E. Participate in small and large group discussions and presentations.
    1.8.8.B. Locate information using appropriate sources and strategies.

  • Science and Technology

    3.2.7. A. Explain and apply scientific and technological knowledge.
    3.2.7. B. Apply process knowledge to make and interpret observations.

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