Looking For a Book About A Missing Link Found(Fiction)

A long time ago I read a book about a scientist in South America finding a living "missing link". He took it home too study it and reveal it to the world. His daughter made friends with it and stuff. I remember one scene where some neighborhood kids have a dog and it attacks her and the missing link fights it off and kills it. The kids attack him for it even though thier dog had been trying too kill the girl. Later it does some thing horrible too the girl. This is all I remember of the book and I need too read it again! Please, if you know the title help! It's not Almost Adam, that takes place in Africa, but it was what I was told too grab at the library. But it wasn't it! Please, help me if you can!