HOW FEATHERS HELP BIRDS FLY

2. A small movable ________ was found in Anchiornis fossils.
3. This bone helped Anchiornis fold its arms to its ________.
5. Birds lift themselves by turning their ________ at a particular angle.
6. These feathers were similar to ________ bird feathers but had the same shape on both sides.
8. Paleontologists study theropod dinosaurs to find ________ about the origin of flight.
10. Feathers helped animals stay warm and attract mates. Over time, they began to help animals ________.
11. Scientists believe feathers evolved because they provided certain ________.
13. One side of the feather is thin and hard, while the other side is long and ________.

1. Anchiornis had feathers on both its arms and ________.
2. Modern birds use the same bone to pull their wings toward their ________ as they fly.
4. Anchiornis is a 150-million-year-old ________.
7. The difference in air ________ allows birds to fly.
9. A bird’s feathers are not the same ________ on each side.
12. Feathered dinosaurs may have evolved flight by jumping from tree to ________.
13. Because of this, Anchiornis probably couldn’t ________.