Pterodactyls

The most distinctive trait of Pteranodon was its cranial crest.

An excerpt from the article 20 facts about pterodactyls
Pteranodon longiceps’ is described as prolonged, blade-like, and pointing backward. However, it could differ depending on age and sex.

Pteranodon sternbergi’s crest was more rounded, and harp-like in appearance, and its size also may have depended on the age and sex.