The spear point you illustrate looks very much like some of the
notched points from the Texas archaic, rather than the high plains
Wyoming. We do find them here once in awhile, however.
I have seen one or
two from a site in the Bighorn Basin on Medicine Lodge Creek.
that it is around 3,000-4,000 years old or so. The material yours
out of looks like the chert that outcrops in the Bridger Formation
Flaming Gorge in southwestern Wyoming.