Given a scientific passage and an answer, generate a question for the given answer.

Passage: Cynodonts probably gave rise to mammals about 200 million years ago. However, they are not considered to be mammals themselves. In fact, competition with early mammals may have led to their extinction. They went extinct sometime during the Jurassic or Cretaceous Period. Answer: mammals
Competition with what emerging animal group may have led to extinction of cynodonts about 200 million years ago?

Passage: When two plates of continental crust collide, the material pushes upward. This forms a high mountain range. The remnants of subducted oceanic crust remain beneath the continental convergence zone. Answer: high mountain range
When two plates of continental crust collide, the material pushes upward and forms what?

Passage: In some soils, the organic portion is entirely missing. This is true of desert sand. At the other extreme, a soil may be completely organic. Peat, found in a bog or swamp, is totally organic soil. Organic materials are necessary for a soil to be fertile. The organic portion provides the nutrients needed for strong plant growth. Answer: no
Will contour lines ever cross?