Well, I quess Petrie and his family are a kind of pterodactylus. I know they gat such a little horn on his head, but even by his mother it's just a little little horn and not such a great, impressive one pteranodons got. It is possible that there were other pterosaurs with a little "thing" on the head. and you got many kinds of pterodactylusses: pterodactylus kochi, pterodactylus antiquus, pterodactylus grandis, ... and so on.
So maybe Petrie and his Family are just a kind of Pterodactylus herbivoris... But on the other hand, it would be handier when Petrie just could be a fish-eater, but LTB's are on that point very intolerant... Great Valley just for vegetarians...
