Use what you learned in the previous lesson to solve real-world problems.

Check what you understood with a short quiz.

Look for the skeletal setup that moved dinosaur legs under the body: an open hip socket, an inturned femur head, and upright hind limbs. Contrast that with sprawling or semi-sprawling reptiles whose legs stick more to the side.

Use what you learned in the previous lesson to solve real-world problems.

Practice weighing several dinosaur markers together, such as three or more sacral vertebrae, a strong deltopectoral crest on the upper arm, and specialized hands and ankles. See why one isolated “reptile-like” bone is not enough to call an animal a dinosaur.

Use what you learned in the previous lesson to solve real-world problems.

Check what you understood with a short quiz.

Sort dinosaurs into the two classic branches by hip layout and early family relationships: saurischians include theropods and sauropodomorphs, while ornithischians include horned, armored, and duck-billed dinosaurs. Untangle the misleading terms “lizard-hipped” and “bird-hipped.”

Use what you learned in the previous lesson to solve real-world problems.

Trace modern birds back to small feathered theropods, so “dinosaur” includes birds in a strict evolutionary sense. Use “non-avian dinosaur” when you mean Triceratops, sauropods, and other dinosaurs that were not birds.

Use what you learned in the previous lesson to solve real-world problems.

Check what you understood with a short quiz.

Identify pterosaurs as flying archosaurs with wing membranes supported mainly by an enormous fourth finger. Place Pteranodon and Quetzalcoatlus near dinosaurs on the family tree, but outside Dinosauria.

Use what you learned in the previous lesson to solve real-world problems.

Distinguish ocean reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs from dinosaurs by their separate ancestry and paddle-shaped aquatic bodies. Recognize that living in the Mesozoic seas did not make an animal a dinosaur.

Use what you learned in the previous lesson to solve real-world problems.

Check what you understood with a short quiz.

Compare dinosaurs with pseudosuchians, the crocodile-line archosaurs that include crocodilians, aetosaurs, rauisuchians, and early crocodylomorphs. Use family-tree position and limb posture to avoid labeling every Triassic land predator as a dinosaur.

Use what you learned in the previous lesson to solve real-world problems.

Sort famous non-dinosaurs such as Dimetrodon, mammoths, and giant ground sloths by asking what group they actually belong to and when they lived. Build the habit of treating “prehistoric animal” as a time label, not a dinosaur label.

Use what you learned in the previous lesson to solve real-world problems.

Check what you understood with a short quiz.

Review this chapter with practice based on your mistakes.