Dinosaurs ate plants. Dinosaurs were eaten by the mammals. Dinosaurs lived on Earth before the mammals. Dinosaurs and mammals lived at the same time.
I gave my students this multiple choice question: Scientists find dinosaur fossils in the bottom rock layers of a cliff and mammal fossils in the middle rock layer of the cliff. Which could best be concluded from this evidence?

Only one answer is correct among these 4 choices:
- Dinosaurs ate plants.
- Dinosaurs were eaten by the mammals.
- Dinosaurs lived on Earth before the mammals.
- Dinosaurs and mammals lived at the same time.

Could you tell me which one is correct?

Dinosaurs lived on Earth before the mammals.