I think that has a lot of variables. Crocodiles were on earth around 250 million years ago, the t rex around 68 million years ago. Crocodiles still breath our atmosphere.
That doesn't mean other animals didn't have different breathing parameters though.
Out of curiosity, why would that matter to most people? I don't live in Europe so I'm just curious. Is it just about wanting them to use the same currency because they seem posh about it or something? On their end I assume the look at it and say our money's worth more. (Why I fabricated the idea of posh being a possible reason for debating for/against)