Idea for Use in the Classroom

Begin by having students describe the dinosaurs they have seen in books or movies. Then introduce the infographic and compare their descriptions to the dinosaurs in the family tree. Have students practice using the key by identifying which dinosaurs showed no evidence of filaments or feathers, then listing which dinosaurs had the types of feathers seen in living birds. Ask: Based on your observations, what patterns exist within the family tree? Have students use their observations to deduce the purpose and structure of a family tree (or cladogram).  

Next, have students analyze the Ornithischian group to propose further branching based on shared characteristics. Discuss what this implies about Ornithischian evolution. Students can perform research to verify their branching patterns.

Refocus on birds by asking: Why might scientists consider Archaeopteryx a transitional form between non-avian dinosaurs and modern birds? Then have students identify patterns of characteristics within the Aves group. Students should find evidence that some characteristics are gained or lost over time. Build upon this idea by having students brainstorm why the common ancestor, basal archosaurs, might have had fuzz, while not all of its descendants do. This can lead to a discussion of natural selection and inheritance of favorable traits.   

Finally, extend the initial discussion by having students consider why older books and movies depict dinosaurs with skin, but not feathers. After fielding responses, ask: Why might scientists have not known about the presence of feathers until recently? Students may note decomposition, consumption, or general destruction as reasons for an incomplete fossil record. Conclude by having students research how scientists finally found evidence of feathers and feather-like structures on dinosaurs.

 

asymmetrical
Adjective

having a different arrangement of parts on either side

cladogram
Noun

chart or diagram showing the points of divergent evolution from a common ancestor.

dinosaur
Noun

very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.

evolution
Noun

change in heritable traits of a population over time.

feather
Noun

one of the light structures that cover the body of birds, often helping them to fly or keep warm.

filament
Noun

very thin fiber or thread-like structure.

phylogenetics
Noun

study of how organisms relate to each other as they develop over time.

pterosaur
Noun

extinct order of flying reptiles that flourished from 220 million-65 million years ago.

Quill knob
Noun

bump on the skin of birds and some dinosaurs that show where feathers or feather-like structures were attached.

symmetrical
Adjective

having the same arrangement of parts on either side.