Archosaurian and Pterosaur

Archosaurian noun - Extinct reptiles including: dinosaurs; plesiosaurs; pterosaurs; ichthyosaurs; thecodonts.

Pterosaur and archosaurian are semantically related. In some cases you can replace term "Pterosaur" with "Archosaurian", this nouns are similar.

Pterosaur noun - An extinct reptile of the Jurassic and Cretaceous having a bird-like beak and membranous wings supported by the very long fourth digit of each forelimb.

Archosaurian and pterosaur are semantically related. You can use "Archosaurian" instead a noun "Pterosaur".