The footprints were left by people approximately 3 1/2 to 6 feet tall; about a third were small enough to be children's.
Their presence suggests that people arrived in the Americas about 40,000 years ago, and challenges the prevailing view that settlers first crossed the Bering Strait from Siberia to Alaska at the end of the last ice age, about 11,000 years ago when a land bridge was in place. Humans could have crossed earlier by water instead of by foot.
Gonzalez says they think there were several migration waves into the Americas at different times by different groups of humans.
Discovery and Live Science have articles about this fascinating discovery.
I've said before on ROfblog, that Native Americans believe that they inhabited this continent much earlier than scientists had stated and the traffic over the Bering Strait went in both directions.
Native Americans say that their ancestors didn't come over the land bridge from Asia some 13,000 years ago. In fact, they have long asserted that their ancestors were here much longer than that and the traffic on the land bridge was in the opposite direction. Native American oral history may be proven correct after all.
For decades the prevailing view was that the first Americans were hunters who crossed a land bridge that connected Siberia and Alaska 13,500 years ago but recent discoveries have spurred controversial theories that they may have come from Europe instead, or they may have been here earlier than previously suspected.
A NOVA documentary is airing on PBS. Check your local listings.