UCMP Lessons  


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 is revealed.

Lesson Concepts:

Grade Span: 6–8


Advance Preparation:

— 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

Teacher Background:

Part I (for use in steps 1–12 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 13–15 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.

  1. 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.
  2. 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. 71–78. In Scotchmoor, J., D. Springer, B. Breithaupt, and A. Fiorillo (eds). Dinosaurs: the Science Behind the Stories. American Geological Institute.

Explore these links for additional information on the topics covered in this lesson:

Teaching Tips:

Prior Internet and print research about Jack Horner’s work will prepare you to enrich the lesson with anecdotes and to respond to students’ questions.

Vocabulary: Orodromeus, Maiasaur, Troödon, horizon, ossified, cartilage, enamel


Day 1

  1. 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.
  2. 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.
  3. Distribute Dino-Data Card #2 (Data 1–4) 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.
  4. Record the proposed “hypotheses” on the board or on a sheet of paper to be saved.
  5. 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.

Day 2

  1. Redistribute Dino-Data Card #1 to each group, along with Dino-Data Envelope (containing Data 1–14). Briefly review what transpired the day before. Read through each of the new pieces of data to make sure that students understand the terminology.
  2. 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.
  3. 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.
  4. 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.
  5. Allow the rest of the period for groups to prepare their presentations.

Day 3

  1. Groups present their hypotheses. Encourage students to respectfully “challenge” proposed hypotheses if they think there is evidence that would disprove those hypotheses.

Day 4

  1. Conduct a discussion regarding which hypotheses seemed the best supported by the evidence. Ask for specifics.
  2. 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.)
  3. 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.
  4. 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.


— Read Maia: A Dinosaur Grows Up by Jack Horner and James Gorman. Have students make comparisons of their hypotheses with those presented in the book.
— Have students 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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