Please see this question for difference in definitions and capitalisation of earth/Earth
In the expression "walk the earth", e.g. "when dinosaurs walked the earth". Should earth be capitalised?
I always assumed that it was referring to the planet, and should therefore be capitalised. However I noticed that a lot of the time it isn't capitalised, indicating that the saying is the equivalent of "walked the ground/soil".
Is there a correct/more accepted usage of this expression? Should earth be capitalised?