It is the finding and analysis of a tip from a human-made projectile point (spearhead) gathered from the remains of a mastodon
I've never felt the previous date to be correct. Man was moving too fast and furious across the landscapes of the world prior to this to be stopped by something as silly as an ocean - even a cold one. I would guess - just a hunch - man has been in and out of the Americas up to 21k ago. Just a hunch.
In any respect, some interesting Archaeology going on.