BACKGROUND:
Like body fossils, trace fossils of extinct animals, such as footprints,
can only be interpreted through comparison with living animals.
Paleontologists thus try to understand dinosaur track ways by studying the
tracks of different types of large mammals in a variety of modern
environments. Mammals are the best modern analogs for dinosaurs because they
walked erectly, like the dinosaurs. For example, elephant tracks and Apatosaurus
dinosaur tracks are very similar. In contrast, modern reptiles have a
sprawled stance that produces a different type of track way than either
dinosaurs or mammals.
Since we are bipedal mammals, we can make tracks that mimic the tracks of
quadrupedal (with four legs) and bipedal (two legs) dinosaurs. In this lab
students will pretend to be different types of dinosaurs which move at
different speeds. They will produce track ways with several distinctive
patterns.
PROCEDURE:
- Students have learned that footprints can give paleontologists
information about how an animal lived or walked. In this activity,
students will "play act" that they are four legged animals
walking in the mud or sand, leaving behind footprints. This activity is
a lot of fun, but it may get the students overexcited. If you have
parent helpers, this would be a good day to have them in the classroom.
We also highly recommend that you conduct this activity outside.
- Divide the class into two or three groups. Have the students pretend
that they are dinosaurs. Have them walk, run, and jump like they think
dinosaurs did before they use the talcum powder or cornstarch
- Have the students make footprints on butcher paper (if you remain
inside) or outside on the school playground. Put the talcum powder or
cornstarch into shallow pans. Demonstrate how to make footprints by
having one student step into the powder, and then walk on the paper or
playground. Observe the pattern of footprints. Have a teacher or adult
do the same thing. See if there is a difference in the size of the print
and the length of stride. Would similar differences in dinosaur tracks
indicate a difference in the size of the dinosaurs that left the tracks?
- Now demonstrate these other ways of making footprints:
- Have another student step into the powder and then walk and drag
the rope (which has also been dipped in powder). Now observe the
track left by dinosaur that dragged its tail.
- Have a child dip both hands and feet in the powder and walk
four-legged. Try this two ways: 1) moving the right hand, then the
left leg, then the left hand, and then the left leg, and 2) moving
both right limbs together, then both left limbs together.
- After you demonstrate, you may want the students to go to separate
areas of the playground and have them make their own footprints. Also,
you may want them to draw the types of footprints which you demonstrated
- Return to the classroom. Using the worksheets, lead a discussion of
the results of your track way experiments. Students should be able to
answer such questions as:
- Are footprints farther apart when an animal is walking or when it
is running? (Answer: running);
- How can you distinguish a two-legged animal's prints from a
four-legged animal's prints? (Answer: placement and spacing of
prints; presence of foot + hand prints);
- How can you estimate the length of an animal's legs from its
tracks? (Answer: distance between footprints is longer for
people/dinosaurs with longer legs than for those with shorter legs,
for two animals moving at the same speed);
- How do bipedal dinosaur tracks differ from human tracks? (Answer:
distance between prints should be shorter).
- Have students cut out the footprints and hand prints on the following
page. Instruct them to paste them onto the worksheet in three different
track ways. Monitor their patterns to ensure that they create realistic
track ways. Have them add a tail in one of the patterns using a pencil
or crayon.
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