Native Americans/American Indians have Sinodont (shovel) teeth (Turner) like most Northern Chinese. Kennewick Man, Spirit Cave man, etc have Sundadont teeth like most SE Asians.
Take this Journey Of Mankind based on the DNA studies of Professor Stephen Oppenheimer. Notice that the haplogroup X arrived early (25,000 ya) at Meadowcroft and became isolated there during the LGM (Last GlacialMaximum).
About 25% of the people in the Ojabiou(sp) tribe (Northern US) have haplogroup X genes, the highest in the Americas.
" Journey Of Mankind" is a nice website although it lacks detail. Unfortunately I can't get my pop-up blocker to quit so I didn't find the page where he connects Meadowcroft to Haplogroup X. Meadowcroft has no human remains so I don't see how that can be done.
Nevertheless, a distinct Haplogroup X found among modern Indians shows just how long their ancestors have been in the New World.
"These findings leave unanswered the question of the geographic source of Native American X2a in the Old World, although our analysis provides new clues about the time of the arrival of haplogroup X in the Americas. Indeed, if we assume that the two complete Native American X sequences (from one Navajo and one Ojibwa) began to diverge while their common ancestor was already in the Americas, we obtain a coalescence time of 18,000 ± 6,800 YBP, implying an arrival time not later than 11,000 YBP.
The results of this study point to the following conclusions. First, haplogroup X variation is completely captured by two ancient clades that display distinctive phylogeographic patterns—X1 is largely restricted to North and East Africa, whereas X2 is spread widely throughout West Eurasia.
Second, it is apparent that the Native American haplogroup X mtDNAs derive from X2 by a unique combination of five mutations.
Third, the few Altaian (Derenko et al. 2001) and Siberian haplogroup X lineages are not related to the Native American cluster, and they are more likely explained by recent gene flow from Europe or from West Asia.
Finally, phylogeography of the subclades of haplogroup X suggests that the Near East is the likely geographical source for the spread of subhaplogroup X2, and the associated population dispersal occurred around, or after, the LGM when the climate ameliorated. The presence of a daughter clade in northern Native Americans testifies to the range of this population expansion."link