I an contemplating about at some point running a new campaign set in the Diamond Throne (3E era setting from Monte Cook, Arcane Unearthed/Evolved), and I haven't really made up my mind. But I am thinking about their being an island with some stranger or rarer creatures, among them a Tarrasque. But it could also feature some Dinos!
Not sure yet if I also want them part of the regular fauna, maybe, maybe not. I don't think the setting description has a clear decision on this, and it wouldn't really matter, since I am doing with it whatever I want in the end.