Homologous Structures: Activity Hand-out
The Olympic counsel wants a profile of some of the competitors. Your job is to figure out the nature of their evolutionary
relationships, which of these four are the most closely related? Because they all look different on the outside you need to investigate
other characteristics in order to figure out these relationships.
PART I. Human Hand/Arm Observation:
On the diagram, identify the bones:
Now, color the diagram following the following guide:
Wrist- green
Phalanges(fingers)- yellow
Ulna & Radius- orange
Carpals (palm)- blue
Humerus- red
PART II. Competitor Skeletal Observation:
1. Observe the following appendages and identify the function:
APPENDAGES
FUNCTION
A. The Bird Wing
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B. The Flipper of the Dolphin
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C. Butterfly Wing
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2. Using the diagram of the human hand & arm, name bones that you can identify on the diagrams provided
A. Bird Wing
B. Flipper of Dolphin
C. Butterfly Wing- Do they have bones?***
Guiding Questions:
Do any of the 4 organisms: human, bird, dolphin, butterfly look similar on the outside? Use specific examples
Do any of the 4 organisms (animals) use the appendages in the same way? Use specific examples
1. Which organism(s) has an internal appendage structure that is different than the others? Explain how you know?
2. For the remaining organisms, describe:
a. How is the internal design of the common appendage similar?
b. How is the internal design different?
3. How would you explain the similarities you see?
4. On the following phylogenetic tree, place the name of the organism in the circle on branch that shows their
evolutionary relationship.
Common ancestor
5. Which organism did you put closest to the human? Why?
6. Which organism branched off from the tree farthest back in time?
7. Write a summary to submit to the Olympic counsel about your findings. Organize your response in a way that clearly
shows which organisms are more closely related using supporting evidence as well as those that are distantly related.
Write a hypothesis to explain the development of the dolphin flipper* (EXTENSION IDEA)
Superficial
Summarize the similarities among these 3:
Identify the differences that you see:
Now, compare and contrast the superficial function with the skeletal structures
Pictures:
Color the homologous structures on the diagrams below
Choose a color to represent one structure