Reading Cladograms
Read and create simple cladograms (branching diagrams) that show how groups of dinosaurs are related based on shared features, understanding that species sharing more features are more closely related
What a learner can do afterwards
- Explain that a cladogram shows evolutionary relationships based on shared features
- Read a simple cladogram to identify which two dinosaurs share the most recent common ancestor
- Add a new species to a partially completed cladogram based on its listed features
1 · Read
Ever wonder why T. rex feels more like a Velociraptor than a Stegosaurus? A cladogram is a branching diagram that shows how groups of dinosaurs are related to each other. Every branch point on it stands for a shared ancestor, an animal that both branches came from.
Here is the key rule: dinosaurs that share more features branch off closer together, near the top. Dinosaurs that share fewer features branch off farther apart, near the bottom.
T. rex and Velociraptor both have sharp teeth, hollow bones, and clawed feet. Stegosaurus has none of those; it has bony plates on its back instead. On the cladogram, T. rex and Velociraptor branch off from a point close together, while Stegosaurus branches off much earlier. If a new dinosaur shows feathers and hollow bones, it joins the branch with the dinosaurs that share those traits.
To add a new dinosaur to a cladogram, look at its features. Find which group already on the diagram matches the most of them, then attach the new branch right next to that group.
A cladogram groups dinosaurs by shared features. The closer two branches meet, the more closely related those dinosaurs are.
2 · Watch
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Where it sits
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Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.