Authors: Judy Scotchmoor and Al Janulaw
Overview: In these lessons students are
presented with a set of data about dinosaurs and asked to hypothesize about
what the data can tell us. Students modify their hypotheses as more information
- Science explains the natural world using evidence from the natural world.
- Scientific ideas are developed through reasoning.
- Scientists pose, test, and revise hypotheses based on research outcomes.
- Science does not prove or conclude; science is always a work in progress.
- Science corrects itself.
- Fossils provide evidence of past life.
Grade Span: 68
- Dino-Data Card #1, one for each group of four students
- Dino-Data Card #2, one for each group of four students (both cards as
- Dino-Data Envelope, containing data points 114 (HTML or pdf), one set for each group.
- Overhead transparencies or paper copies of the three dinosaurs (HTML or pdf) and Egg Mountain
Copy Dino-Data Cards #1 and #2. One for each group of students. Laminate
them for future use, if you choose.
Copy and cut apart
the 14 pieces of Dino Data. Place them in envelopes, one for each group. These
may also be laminated.
Time: Four class periods
Grouping: Threes or fours and whole class
Part I (for use in steps 112 of the Procedure)
Through the work of Jack Horner and other scientists, it has been learned that several
different dinosaurs lived at the same time (roughly 80 million years ago) in Montana.
Three of these dinosaurs were Orodromeus (mountain runner), a swift plant eater;
Troödon (wounding teeth), a small but fierce predator (carnivore); and
Maiasaura (good mother lizard), a larger herbivore. There is good fossil evidence
to show that all three laid eggs in nests. The nesting sites included two islands
surrounded by a shallow alkaline lake. The environment at that time included volcanoes
and a few mountains to the west (not the Rockies as they were in the process of
uplifting) and to the east, a warm interior seaway which divided North America from
north to south.
Part II (for use in steps 1315 of the Procedure)
For thirteen years, evidence found by Horner and colleagues confirmed that
there were two types of nests found at this locality and that they belonged
to two different dinosaurs. Skeletal and embryonic evidence supported the
hypothesis that one type of nest belonged to the dinosaur Maiasaura. An abundance
of Orodromeus skeletons and the rarity of Troödon bones
at the Egg Mountain supported the hypothesis that the second type of nests
was that of Orodromeus. And when embryonic
remains were discovered in a clutch of eggs at the Egg Island site, preliminary
studies suggested that these were most likely those of Orodromeus. However, there
were two discoveries that would lead
to the falsification of this hypothesis.
- In 1993 David Varricchio discovered the hind end of an adult skeleton
of Troödon on top of what was thought to be a clutch of Orodromeus eggs.
- In 1995, Mark Norell and others published a paper on a skeleton of another
dinosaur, Oviraptor, from Mongolia.
This skeleton was found squatting over what was assumed to be a nest of Protoceratops
due to the numerous skeletons of Protoceratops
in the area. However, it was found that one of the eggs contained an embryo
of Oviraptor, thus overturning the previous hypothesis. Most likely
Oviraptor was sitting on its
own eggs, not feeding on those of another!
As the Oviraptor was squatting in
much the same position as the Troödon found by Varricchio, the Egg Island embryos
were further prepared and more thoroughly studied. The examination revealed that the embryos
were in fact Troödon, falsifying the long held hypothesis that Orodromeus
had been the egg layer.
So, if the nests were those of Troödon, why all the bones of Orodromeus? The
current hypothesis is that Troödon dragged the carcasses of Orodromeus to the
nesting area for their hatchlings to feed on.
Reference: Horner, J.H. 2002. Evidence
of dinosaur social behavior, pp. 7178. In Scotchmoor, J., D. Springer,
B. Breithaupt, and A. Fiorillo (eds). Dinosaurs: the Science Behind the Stories. American
Explore these links for additional information on the topics covered in this lesson:
Prior Internet and print research about Jack Horners work will prepare you
to enrich the lesson with anecdotes and to respond to students questions.
Vocabulary: Orodromeus, Maiasaur, Troödon,
horizon, ossified, cartilage, enamel
- Tell the class that they are
about to participate in an investigation about dinosaurs in which information
is revealed to them in much the same way evidence is revealed to scientists.
They will be asked to explain what they think one can learn about the dinosaurs
from the evidence they have. Then, as they receive additional information,
they will be asked to re-explain what they think went on.
- Distribute Dino-Data Card
#1 to groups of students and read through it with them. Show the illustrations of
the three dinosaurs discussed on the card.
- Distribute Dino-Data Card
#2 (Data 14) to each group. Read through the data card with the whole class
and ask the class to brainstorm about what we can learn about the Montana
dinosaurs from the evidence on the cards. Example: #1 states
that Maiasaurs probably ate nearly 200 lb. of vegetation each day. #4 states
that they have been found in herds up to 10,000 in number. A class discussion
around these two points might result in a hypothesis such as, Because each
Maiasaur consumes 200 lb. of vegetation per day and herds numbered as large
as 10,000, the Maiasaurs must have migrated because they would need to find
new food sources.
- Record the proposed hypotheses on the board or on a sheet of paper to be saved.
- Conduct a whole-class discussion:
which of the hypotheses are supported by the data that have been given. Is
this hypothesis supported by the data? Note that some students may bring
prior knowledge to the discussion or make inferences that go beyond what is
contained in the given Data. Hold the class to this standard as you briefly
discuss the various hypotheses. Leave the hypotheses posted for future reference.
- Redistribute Dino-Data Card #1 to each group,
along with Dino-Data Envelope (containing Data 114). Briefly review what
transpired the day before. Read through each of the new pieces of data to
make sure that students understand the terminology.
- Ask the groups to lay out
all the data they now have (new and old) and to brainstorm with one another
what the data might reveal about the dinosaurs. Each group should write at
least three hypotheses based on the evidence.
- Have the groups write their
hypotheses with the information that provide evidence to support each hypothesis.
Also ask them to list what additional information they would need to further
support or eliminate each hypothesis.
- After each group has completed
work on the three hypotheses, ask them to select one hypothesis that they
find particularly interesting and to prepare a presentation for the class.
Each presentation should clearly state the hypothesis, the evidence for the
hypothesis, possible weaknesses of the hypothesis, and what additional information
they would need to further test the hypothesis.
- Allow the rest of the period
for groups to prepare their presentations.
- Groups present their hypotheses.
Encourage students to respectfully challenge proposed hypotheses if they
think there is evidence that would disprove those hypotheses.
- Conduct a discussion regarding
which hypotheses seemed the best supported by the evidence. Ask for specifics.
- Tell the class that you have
just received some breaking news: Further study indicates that what were thought
to be Orodromeus nests have turned out to be Troödon nests. Ask students
to discuss and write
what effect this new information has on their hypotheses. Ask also what additional
information they now need to make sense of what happened with the dinosaurs.
(Note: This new information is likely to upset many of the students hypotheses.
See Teacher Background, Part II for details.)
- At this point,
you might ask the groups to further modify their hypotheses based on the new
information, with consequent discussion, or go on to step 15.
- Conduct a large group discussion.
What have we learned about how science works from this experience? Establish
with the group at least these points: Scientists work from evidence. Scientists
formulate multiple hypotheses. Scientists eliminate or modify hypotheses as
evidence comes in. New evidence is always changing our ideas about how things
work. In science, we often learn more from being wrong than from being right.
A Dinosaur Grows Up by Jack Horner and James Gorman. Have students make
comparisons of their hypotheses with those presented in the book.
note the use of modern birds in the Dino-Data. Making comparisons to living
organisms is a useful tool for scientists working with the past. Can students
think of other examples?
Can students think of
any possible experiments to test their hypotheses? For example, it might be
fruitful to consider herds of large herbivorous animals today. Do they migrate?
Updated November 20, 2003
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