There is very little that can be said with great confidence about the earliest Americana. Various methods over the decades have been used to try to piece together American prehistory, and pretty much every attempt had given different conclusions. This is even true of normally reliable methods like mitochondrial DNA. There is a consensus that there are 4 distinct haplotypes (Toroni 2000 "Mitochondrial DNA and the origin of Native Americans", in "America past, America present) but no agreement of what history they represent.
Satoshu Horai (1993) argued for 4 separate waves of migration between 21 and 14,000 years ago. Toroni (1994) argued for 2 waves, the first around 29-22,000 years ago, the second somewhat later. Bonatto and Salzano (1997) ton much the same data as showing a single migration wave more than 25,000 years ago.
The problem is partly lack of data: by 2000 there were only 37 individuals whose remains date to before 9000 BC, and they are mostly just a few bone fragments (Chatters, 2000, "The recovery and first analysis of an early Holocene human skeleton from Kennewick, Washington", American Antiquity 65, 291-316)
The specific claim mentioned in the question appears to derive from Steele and Powell (1994, "Paleobiological evidence for the peopling of the Americas: a morphometric view" Method and Theory for Investigating the Peopling of the Americas pp 141-163) which is the origin of the claim that the pre 9000 BC remains are morphologically distinct from modern Native Americans, and have more in common with modern African features, or early aboriginal Australians (60,000 years ago).
Morphological similarity is far from being evidence of a close evolutionary association however.
All of which seems to amount to a resounding "nobody really knows right now, and there isn't conclusive evidence to support any particular theory".