Pterosaurs were not too big to fly. Some of the largest pterosaurs, such as _Quetzalcoatlus northropi_, had wingspans of up to 10 meters (33 feet), but they were able to fly because of their light, hollow bones and their wings, which were made of a thin membrane of skin stretched over a framework of long, thin bones.

The lightest pterosaurs, such as the _Rhamphorhynchus_, weighed only about 2 kilograms (4.4 pounds), and even the largest pterosaurs, such as the _Quetzalcoatlus_, weighed only about 250 kilograms (551 pounds). This is much less than the weight of a human being, which is around 70 kilograms (154 pounds).

Pterosaurs were able to fly because of their light weight and their large wings. Their wings were also very flexible, which allowed them to soar and glide through the air. Pterosaurs were also very strong fliers, and they could reach speeds of up to 60 kilometers per hour (37 miles per hour).

Pterosaurs were able to use their wings to fly because they:

- had a small body weight

- long and slender bones

- large, flexible wings

- strong flight muscles

- lived during a time when there were not too many trees