Figure out things that can cause extinction to the entire dinosaur species. Below are the key words to help you get the golden crown.

Set 1: Sun
Set 2: Disease
Set 3: Virus

Other Answers:
Erupting volcano

Scribblenauts Remix 2-2 Cheats Hints gallery:
2-2-1-a: Cause a new extinction event without weapons or asteroids!
2-2-1-b: Create a global epidemic.
2-2-1-c: Make the dinosaurs sick.