I can start you with some facts of the accepted timeline for man in the Western Hemisphere. I am citing George Carter.
Earlier Than You Think, Texas A&M University Press, 1980.
On page 7 he writes:"In the 1930's we were taught that the first immigrants entered America about 5,000 years ago, just prior to the beginning of the Neolithic, the time of revolutionary changes in life-style marked by the beginning of domestication of plants and animals."
A. L. Kroeber was the leading authority back then and he also considered a time for early man as recent as 2,500 to 3,000 years based on the belief that the entry of man into the Western Hemisphere was about the same time as the adoption of the (then) modern bow and aroow which just earlier thatn the time of Christ. That was considered an extreme date even then. 5,000 and under years was the generally accepted date in the 1930s.
Again citing Carter, from 1940 to 1970 the accepted earliest date was 10,000 and under. The figure usually given was 7,000 years, give or take several thousand. Carter began to fight for an earlier date, with practically no success at all, in 1950.(Page 15) There the subject lay until later finds and new and ever better dating systems pushed the date past 10,000 to the recently believed date of 12,000, taught in college as late as the 1960s.
I'd love to teach a course of the subject but I'm not able to do that. I have given you some facts and a pair of cites. The rest can be found with a little online searching.
http://www.smithsonianmag.com/scienc...209273/?no-ist
https://genographic.nationalgeograph...human-journey/