The bulk update request #10070 has been approved by @nonamethanks.
create alias pterodactyl -> pterosaur
create alias pteranodon -> pterosaur
1. "Pterodactyl" can be used either as an informal term for all pterosaurs, or specifically for those from the genus Pterodactylus, which makes it an ambiguous tag already.
2. "Pteranodon", by contrast, is a specific genus, and some posts tagged pteranodon are other pterosaurs (like the one in post #3204437, which has teeth).
3. In many posts with various pterosaur tags, they're seen in the distance or stylized in such a way that it's impossible to tell which genus was meant (e.g. post #3795199, post #4480419).
4. I don't think we have any hardcore dinosaur nerds on here who'd care too much about the difference.