What do the animals use as a gauge for the passage of time?
Do they even care what year it is?
I start with this, because the question seems to presume we were thinking then as we do now, which may not be the case.
In debates and discussions about the Saturn theory, the idea that the events may even have been the cause of, or helped, the awakening of man to his present state of consciousness, often gets proposed.
Maybe we simply weren't the timekeepers back then, that we are now.
With no seasons, there wouldn't be such a need.
Just throwing that in as a possibility to consider.
Or maybe what others say is right, and we had advanced technologies way back then,
and used atomic clocks.
Before Atlantis sunk.