Identify Trace Fossils

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Updated on Apr 26, 2013

How can scientists figure out what a dinosaur’s footprints looked like? When a dinosaur walked near a stream, it may have left footprints imprinted in the earth. If the stream the footprints flooded, mud might have filled them and dried, preserving them forever. This science project will allow you demonstrate this process, which eventually forms a trace fossil.


How do trace fossils form?


  • Clay
  • Margarine container
  • Cooking spray
  • Plaster of paris
  • Water (to make plaster)
  • Seashell


  1. Place some clay into the bottom of the container, and flatting it so that it is at least ½-inch deep.
  2. Spray the surface of the clay, as well as the visible sides of the container, with cooking spray.
  3. Lay the seashell on top of the clay, with the most textured side facing downwards.
  4. Press onto the seashell and then remove it, so that it leaves a deep impression in the clay.
  5. Use the directions on the package of plaster of paris to make about ½ cup of plaster.
  6. Pour the plaster over the clay so that it completely covers the seashell impression.
  7. Wait at least 30 minutes for the plaster to dry completely.
  8. Squeeze the container so that the piece of clay and plaster pops out of it. Peel the clay off to reveal the plaster “fossil.”
  9. Consider how this fossil resembles trace fossils made from animal footprints. What does the clay represent? What does the plaster represent?
Keren Perles has worked as an educational writer, editor, teacher, and tutor of all ages. Her experience spans the subject areas, from science and math, to English and the Hebrew language.

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