You probably know that lions were native to Greece 2,000 years ago (ergo, the Lion Gate). But more importantly I just realized today how important it might be that the rats we know of as rats are relative newcomers to Western Eurasia (above & beyond their specific relevance to plague). The black rat for example seems to have arrived in the Mediterranean just as lions were going extinct, during the days of the Roman Empire. But today the black rat is rare in Europe (generally found in port cities) and has been replaced by the brown rat, which only arrived in the early modern period (e.g., 18th century in Britain). So check out Rats, Communications, and Plague: Toward an Ecological History.