Stone Spheres of Costa Rica:
Sometimes referred to as the Diquís Spheres, there are over 300 of them located on the Diquís Delta and on Isla del Caño, Costa Rica. It is uncertain as to what they were really used for, but the best estimate is that they were placed in lines that lead to the houses of chiefs.
or they are respectful that not all religions utilize the same calendar...
"When in Rome..."
...I use my own d@$% calendar, and I expect everyone else to accommodate me!!!!!
Darwin has nothing to do with historical timelines.
https://en.wikipedia.org/wiki/Sacsayhuam%C3%A1n
What we're talking about is the Norse settlements leading to the settling of the North American continent. Greenland because of it's proximity to N. America is the reason it's included.