ALAN NAGAHISA

PREHISTORIC MESOSAURUS

GRADES 6 - 8

LOCATION; MOVEMENT; REGION; ASKING GEOGRAPHICAL QUESTIONS; INTERPRETATION OF GEOGRAPHICAL INFORMATION

INTRODUCTION:

The lesson introduces the theory of plate tectonics, which succeeds Alfred Wegener's older hypothesis of continental drift. It uses the evidence provided by a 280 million-year-old swimming reptile named Mesosaurus.

OBJECTIVES:

The student will be able to:

1. Locate the only two places where the Mesosaurus fossils have been found.

2. Identify the geological period when the reptile lived.

3. Locate, on a map of Pangaea, the localities where Mesosaurus lived.

4. Describe the habitat where Mesosaurus lived.

5. Draw conclusions why Mesosaurus has only been found in Africa and Brazil and how its fossil remains serve as important evidence that shows where two continents were once joined together.

6. Explain the rudiments of plate tectonic theory as it relates to the movement of continents.

MATERIALS:

Overhead projector

Transparent plastic sheets (may be cut from large freezer bags)

Skeleton drawing of Mesosaurus suitable for cutting up for assembly in class

Dinosaur resource book

Fossil resource books

World map of the Quaternary period that can be cut up in class

World map of the Permian period

PROCEDURE:

1. Students form groups of four or five.

2. Students will first research the Mesosaurus, discover what it looked like, what it ate, where it lived, and where the fossil remains have been found.

Teacher will cut up the drawing of the Mesosaurus skeleton and make copies of the bones in disarray that are distributed to study groups. The groups can cut them up and reassemble them, gluing them together in appropriate order. Students can draw the animal from their paper fossil evidence and finally, compare it with the artist's rendering in the fossil book

3. Students will locate, on a current map of the world where the fossils were found.

4. Students will locate on a map of the world of the Permian period, where the fossils were found. The map of the present world may be cut apart and the continents placed in their approximate locations during the Permian period.

Teacher can help demonstrate by tracing outlines, in their present relative locations, of Africa and South America, but with the continents on two sides of a large plastic freezer bag that has been cut apart at its seams. When the bag is "unzipped", the continental images can be slipped back and forth over one another and viewed by the class the with aid of an overhead projector. The localities of fossils of mesosaurus can be marked with red dots.

5. Students will discuss what it means that this Mesosaurus, which has only been found twice in the entire world, appears in two places nearby in the same district when the two continents once met in the Permian period, but that are now separated by the width of the Atlantic Ocean.

6. Students will draw conclusions about how continents have drifted over the past 280 million years.

EXTENSIONS:

The lesson can be modified using other trace fossils, such as trilobites, that have been used to establish particular time periods in earth's history.

SOURCES: check all.

Arduini, P., and G. Teruzzi. Prehistoric Atlas. London: Macdonald and Co. 1982.

Case, Gerald. A Pictorial Guide to Fossils. New York: Van Nostrand Reinhold Co. 1982.

Fenton, C., and M. Fenton. Thre Fossil Book. New York:. Doubleday. 1989.

Pinna, Giovanni. The Illustrated Encyclopedia of Fossils. New York: Facts on File.1990.

Steel, A., and A. Harvey, eds. The Encyclopedia of Prehistoric Life. New York:

Gramercy. 1979.