The Tree/Web of Life (Lesson 12: Archosaurians)

Reptiles_archosaurians: birds, the flying dinosaurs.
[ezcol_1quarter]Main Idea:[/ezcol_1quarter] [ezcol_3quarter_end] The reptiles appeared 320 million years ago. Reptiles are comprised of the lepidosaurs (turtles, lizards and snakes) and the archosaurians (crocodiles and birds). The ancestors of birds adopted numerous characteristics that helped them diversify into the countless species we see today.[/ezcol_3quarter_end]

[ezcol_1quarter]Objectives:[/ezcol_1quarter] [ezcol_3quarter_end] 1. To explain where birds fit in the Tree/Web of Life and in relation to other reptiles.
2. To learn the characteristics that make birds successful in their environment.
3. To observe, analyze, and make hypotheses as to how feathers helped birds to adapt to new environments. [/ezcol_3quarter_end]

[ezcol_1quarter]Students’ Skills:[/ezcol_1quarter] [ezcol_3quarter_end] Observation, evaluation, comprehension, application, analysis, and synthesis: These processes were drawn from Bloom’s Taxonomy and the constructivist list. NGSS connections: MS-LS1 From Molecules to Organisms: Structures and Processes; MS-LS2 Ecosystems: Interactions, Energy, and Dynamics; and MS-LS4 Biological Evolution: Unity and Diversity.[/ezcol_3quarter_end]

[ezcol_1quarter]Materials[/ezcol_1quarter] [ezcol_3quarter_end] 1. For the lecture and discussion: textbooks, material reference, PowerPoint presentation.
2. For the activity: computer, handout, crayons, paper, and different types of feathers.[/ezcol_3quarter_end]

[ezcol_1quarter]Lesson:[/ezcol_1quarter] [ezcol_3quarter_end]1. Entry card: What makes a bird a bird? Pick your favorite bird, and write three characteristics that help them survive. Allow time for the students to think and to write down their answers. Follow this up with a whole-class discussion of some of the points students made. Lead the discussion towards ideas like new habitats and the structure/function relationship of adaptations. Answer the students’ questions, and write their ideas on the board.

2. Communicate to your students the topic of study, the importance of learning it, the objectives, and how this class relates to past lessons. Refer to what was happening on Earth when the reptiles appeared on land. Write the objectives on the board.

3. Part I: The students will help solve a controversy posed by a confused scientist. The question is whether birds are more like lizards, crocodiles, or dinosaurs. The students will compare these animals, make a list of characteristics, and construct a table to help illustrate their findings. Make sure students know that they are making a hypothesis, and that since one of our animals is no longer alive, they will be extrapolating.

4. Have the students read aloud the problem on the handout: “Our scientist friend is back! She was very impressed with our help last time she visited us. Her problem this time is that she wants to settle a controversy with some of her peers. The question is whether birds are more like lizards, crocodiles, or dinosaurs. Yes, dinosaurs are extinct, but we can look at the fossils to gather information.”

5. Present the data to the students. First: Show the students a clip depicting the locomotion of a lizard, a crocodile, and a modern bird. You can obtain these materials from any of several documentaries online (PBS, NOVA, etc.). Then show the skeletons of these animals plus the skeleton of a dinosaur (T. Rex will do nicely), side by side, on a PowerPoint slide or chart. Ask the students to compare the skeletons and answer the first three questions on their handout. Keep the chart visible throughout the whole lesson.

6. The students could work in groups of two or three. Ask them to identify as many differences and similarities among the four creatures in the board as they can. Using these observations, students should start filling in the table. Answer questions five and six in the handout.

7. Part II: The students will have different type of feathers (flight feather, body feather, and a down feather), and they will make observations as to the feathers’ characteristics and structures. Show a diagram on the board depicting the main parts of a feather. Stop after this activity and engage the students in a discussion of the importance of feathers in the development of flight.

8. With all this information, each student will produce a small paragraph reporting his or her conclusions to our scientist. Make sure students know that each statement should be followed by a sentence addressing the reason: “I think … because …”

9. Exit card: Please revise your entry card and write three things you learned today, two things you are confused about, and one thing you really want to know.

[ezcol_1quarter]Class Closing:[/ezcol_1quarter] [ezcol_3quarter_end] 1. Collect entry/exit cards.
2. Homework: Improve your handout using a different colored pen, and bring it to class. Write a paragraph on the idea that birds are “modern dinosaurs,” discussing whether you agree or not and why. [/ezcol_3quarter_end]

[ezcol_1quarter]Assesment:[/ezcol_1quarter] [ezcol_3quarter_end] 1. Participation in class and discussions. Presentation of results, and thoroughness and detail in filling out handouts.
2. Grading: Homework.
3. Use a general rubric to evaluate the students’ overall performance.[/ezcol_3quarter_end]

[ezcol_1quarter]Teacher’s Reflections[/ezcol_1quarter] [ezcol_3quarter_end] 1. Things that I did not cover.
2. Did I meet the lesson objectives?
3. Comments, conclusions, and modifications.
4. Pedagogical value of the lesson. Did my students learn the concepts and ideas explored in this class? Did the assessments provide enough evidence of understanding?[/ezcol_3quarter_end]

[ezcol_1quarter]Notes to the Teacher[/ezcol_1quarter] [ezcol_3quarter_end]

1. There are plenty of educational videos from the National Geographic Society, BBC, PBS, and HHMI that can be used to show these animals in motion, as well as their skeletons.

2. Make sure you talk about and illustrate the idea that the transition from non-flying theropods (dinosaurs) to birds consisted of major modifications such as endothermia, ability to fly, etc.

3. It is important to point out that birds and dinosaurs have a modified ankle (hinge-like) that allows/allowed them to have their legs under their bodies (not sprawling), making their gait erect and active. Also, they are warm-blooded; constant temperature allows the exploration of more habitats and an active lifestyle.

4. Make sure to talk about what the Earth’s environment look like at these different points in the history of life.




Reptiles appeared 302 mya. They comprise the Lepidosaurs: turtles, lizards and snakes and the Archosaurians: crocodiles and birds. 

cropped-owlet_logo.gifThe archosaurs include the birds, crocodiles, and the extinct dinosaurs. We are going to learn where birds come from and, at the same time, help our scientist friend. Also, we are going to find out what adaptations allowed birds to become very successful in the air.

“Our scientist friend is back! She was very impressed with our help last time she came by. Her problem this time is that she wants to settle a controversy with some of her peers. The question is whether birds are more like lizards, crocodiles, or dinosaurs. Yes, dinosaurs are extinct, but we can look at the fossils to gather information.” She brought some materials for us to use.

Your teacher is going to show you a video clip and pictures of the skeletons of a lizard, an extinct dinosaur (T. Rex), and a modern bird (living dinosaur). Your task is to compare them, think of their similarities and differences, and answer the following questions:

1. Describe the locomotion (the way they walk) of the lizard, the crocodile, and the bird. Notice the direction of their limbs, and the position of the head and back.



2. Does the way their skeletons are built explain their gait (walk)? How? Use the words “erect” and “sprawling” in your answer. How do you think T. Rex walked?



3. Who do you think will be more agile and be able to run longer and faster? Why?




4. Fill the table bellow:


5. Look at the column of the bird: What characteristics do you think are important to allow the bird to fly? How are these traits (characteristics) advantageous?




6. In what ways are present-day birds similar to ancient dinosaurs? In what ways are they different?




7. Examine the different type of feathers provided. How are they similar/different?




8. Why are feathers an important feature of birds?




9. Your teacher will show a diagram with the most important parts of a feather. Draw and describe the STRUCTURE and FUNCTION of a feather.


10. Report to our scientist. With all the information gathered, produce a small paragraph reporting your conclusions to our scientist. Make sure that when you make a statement, you follow it by giving the reason: “I think … because …”