The article still seems problematic though. They're really pushing it in the second section, like the wording was changed to just barely be factual or impressive. Or not. For example,

>Native Americans also posited that megafauna like giant beavers and bison had shrunk to their present sizes over time.

They picked the bison right, since that basically did just shrink directly to the modern form. The giant beaver however is unrelated to the modern beaver. Same with the other megafauna -- simply shrinking seems to be a major exception.