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Answers to Exploration Questions: What is a dinosaur?

If you are wondering where the suggested answers came from, you can review the video and the articles in this tutorial.
1. All dinosaurs evolved from the very first dinosaur, the common ancestor. What do scientists know about this common ancestor?
Answer: Scientists haven’t found fossils of the common ancestor. However, they can determine its characteristics based on traits that are shared by all dinosaurs that were new and unique to this group of animals.
2. Archaeopteryx was the most primitive known bird. How was _Archaeopteryx_similar to modern birds? How was it different from modern birds, and more like advanced non-avian dinosaurs?
Answer: Like modern birds, Archaeopteryx had feathers, wishbones, breastbones, a crescent-shaped wrist bone, and feet with three main toes. But it also shared some features with advanced therapods that are unlike modern birds, such as a long bony tail and teeth.
3. Explain how a cladogram works.
Answer: A cladogram is a branching diagram that shows evolutionary relationships between different groups of organisms. Organisms with like features are grouped together. Every branching point represents a physical feature that’s unique to that group.

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