Title: No Bones about It: Reconstructing a Mosasaur
Author: Don Vincent, West High School, Madison, WI. 53705
Grades: 3-10
Overview of Lesson:
In this activity, students will model a paleontologist’s activities. When finished, they will be able to identify bones from a mosasaur and reconstruct its skeleton, reassembling bones of an extinct reptile. It is a difficult job; putting together bones of any extinct animal can be frustrating. Often the bones are mixed up and in many cases, some of the bones are missing.

Paleontologists use their knowledge of biology and comparative anatomy to assemble these extinct animals. When reconstructing a newly discovered and previously unknown skeleton, they may compare the bones to those of similar species to get an idea of how to assemble it. However, scientist do not always get it right the first time.

Suggested Time: 45-50 minutes

Students' Prior Knowledge:
Students have been introduced to the concepts of bones (shape, size, function) and comparative anatomy of one animal to another. Students should have some appreciation for scale comparisons. Students should be introduced to the vocabulary.

Background Information:
Students are shown that paleontologist often finds fossils like bones and artifacts scattered and out of order. Students will learn that this process is based on current information about modern animals found on Earth.

instructions and one set of mosasaur bones per group
Figure 1 - detailed drawing of a mosasaur’s flipper
Figure 2 - drawing of a mosasaur
Figure 3 - mosasaur skeleton

Student Activity:
Students are in small cooperative groups to perform the tasks. Each group should carefully observe all of the bones in their packet. Students should try to keep the bones in order and estimate where they should be connected. Students may want to refer to the diagram of a complete mosasaur and try to arrange their bones.

Teacher Notes:
The purpose of this lesson is to have students use inquiry to determine the arrangement of bones of an extinct reptile. Students may become frustrated if they can not put all the pieces together right away. Figure 1 is a detailed hand drawing of a mosasaur’s flipper. Make copies and then cut out each individual bone or several bones together, depending on the desired difficulty of this exercise. Encourage your students to take time and to review Figure 2 which shows an artist’s conception of what a mosasaur might have looked like when it swam in the Cretaceous Sea some 80 million years ago. Included is a copy of a completed mosasaur skeleton in Figure 3. Use pictures of other animals, for example, shark, whale, or fish and compare them with a mosasaur. In addition to comparing bone structure, look at habitat comparisons or adaptions that each animal has made in order to become sucessful.

Involve students in a discussion while answering the following questions. Answers will vary but students should have a sense what it is like to be a paleontologist.

Questions for students to think about:
1. What clues did you you use when you started to assemble your mosasaur?

2. If you had not seen Figure 1. would you have been able to complete this skeleton? Why or why not?

3. What kind of skills do paleontologist need to have in order to assemble extinct animals.

paleontologist, mosasaur, anatomy, Cretaceous

Interdisciplinary Connections:
Math- Use of scale,
Social Studies- Use of scale.
Language Arts- Writing directions, using reference materials, reading about dinosaur digs.

Extension Activities:
Reading books about Mosasaurs including: A Dinosaur Dynasty by Katherine Rogers, Colorado’s Dinosaurs by John T. Jenkins, Jr. and Janice L. Jenkins, and Discover magazine; September 1993.
*Scale drawings of other animals.
*Draw 2-D or make 3-D models, investigating the size of real dinosaurs and other prehistoric creatures. (Carnegie models work well.)

Wisconsin State Science Standards:

When investigating a science-related problem, decide what data can be collected to determine the most useful explanations


Use simple science equipment including rulers safely and effectively to collect data relevant to questions and investigations


Communicate the results of their investigations in ways their audiences will understand by using charts, graphs, drawings, written descriptions, and various other means


Develop descriptions* of the land and water masses of the earth and of Wisconsin's rocks and minerals, using the common vocabulary of earth and space science


Using the science themes*, explain* and predict* changes* in major features of land, water, and atmospheric systems


Describe* underlying structures of the earth that cause changes* in the earth's surface


Using the science themes* during the process of investigation*, describe* climate, weather, ocean currents, soil movements and changes* in the forces acting on the earth


Using the science themes*, analyze* the influence living organisms have had on the earth's systems,
E.8.5 Analyze* the geologic and life history of the earth, including change* over time, using various forms of scientific evidence


Using the science themes*, describe* theories of the origins and evolution* of the universe and solar system, including the
earth system* as a part of the solar system, and relate* these theories and their implications to geologic time on earth