Did the Greeks know the earth was a sphere before Eratosthenes' experiment?

Eratosthenes was a Greek mathematician that conjectured that the earth was a sphere around 250 BC. He did this by measuring the angle of shadows on the bottom of two different wells. One well was in Alexandria, Egypt, and the other was in Syrene, Egypt. The well in Syrene had less of a shadow at noon than the well in Alexandria, meaning that the sun was hitting the wells at different angles. Eratosthanes calculated the circumference of earth to within about 150 kilometers.

My question is: The Greeks had a god named Atlas that carried the weight of the world on his shoulders. Whenever you see a sculpture of Atlas, he is holding a giant sphere on his shoulders. Did the idea that Atlas was carrying a sphere come about before Eratosthenes did his experiment? Or did they make this conclusion after Eratosthenes concluded the earth was a sphere, and not flat?

IIRC, the modern statues of Atlas have their roots in the Rennaissance, when it was known that the Earth was a sphere. However, I believe the Greeks knew the Earth was a sphere before Erostosthenes simply by observing the round shadow it makes on the moon.

In any case, Atlas actually held up the heavens (i.e. the sky) not the Earth.

Mercator’s son put a picture of Altas bearing the globe at the front of his book of maps in 1555. That may or may not be the earliest depiction of Atlas carrying the earth. Kat is right that in ancient mythology, the Titan Atlas bore the heavens, not the earth, on his shoulders.

Eratosthenes was (as far as I know) the first to make an absolute measure of the size of the earth, but not the first to believe the earth was a sphere. A generation earlier, Aristarchus assumed the earth was a sphere and measured the relative size of the earth and moon (and the relative distance to the moon and sun) by observing lunar eclipses.

Pythagoras may have been the first Greek to believe the earth was a sphere. Heracleides, Parmenides, and Aristotle were other believers who all came before the time of Eratosthenes and Aristarchus. I’m not sure what evidence their beliefs were based on.

A lot of the Pythagorean beliefs are attributable to the group of Pythagoreans, but they were secretive and didn’t reveal some of their sources, no?