Humans and buffalo. Humans and passenger pigeons. Humans and mastodons. Humans and elephants. Humans and tigers. Humans and smallpox. Humans and dodos. Etc.
No, I just wanted to make sure you weren't conflating what happens to species with what happened with Columbus and Hispaniola. I'm not so sure we know in enough detail exactly what happened to Neanderthals for that to be a good example, especially since the conversation is about the meeting of different civilizations, not just different species.
Name the occurrences where they did. That word, species, I'm not so sure you know what it means.