Quibble. There's no evidence that the horse died out, or that the horse was reintroduced by Coronado's expedition. Evidence would include a post-it note from Coronado, saying, "oh, and we lost a bunch of horses today". Good points regarding PreColumbian plants, and I'd also add the "Cocaine mummies" evidence.
I agree. No argument here. I have a nasty habit of trying to make people see the logic of a statement, however, and that tends to get me into trouble of sorts.
;o]
Egpytians mummies containing traces of cocaine and caffeine, it's like a kick in the nuts of established Egyptology.
I saw a doc on it, and the lady scientist who discovered it got a lot of angry letters from fellow archeologists calling her anything from a fraud to just plain stupid.
Even though the findings where verified by at least three other laboratories.