Feathers and flight

1. Feathers helped animals stay warm, attract ________, and eventually fly.
6. Because of this, Anchiornis probably couldn’t ________.
9. Anchiornis had feathers on both its arms and ________.
11. Feathered dinosaurs may have evolved flight by jumping from tree to ________.
12. A small movable ________ was found in Anchiornis fossils.
13. This bone helped Anchiornis fold its arms to its ________.
14. The difference in air ________ allows birds to fly.
15. These feathers were similar to ________ bird feathers but had the same shape on both sides.

2. Scientists believe feathers evolved because they provided certain ________.
3. One side of the feather is thin and hard, while the other side is long and ________.
4. Modern birds use the same bone to pull their wings toward their ________ as they fly.
5. Paleontologists study theropod dinosaurs to find ________ about the origin of flight.
7. Anchiornis is a 150-million-year-old ________.
8. Birds lift themselves by turning their ________ at a particular angle.
10. A bird’s feathers are not the same ________ on each side.