russets and ochres and siennas outlined charging boars and fleeing gazelles , woolly mastodons and giant sloths : he imagined that the paintings had to be thousands of years old , but then they turned a corner , and he noticed that , in the same style , there were lorries , house cats , cars , and-markedly inferior to the other images , as if only glimpsed infrequently , and from a long way away-airplanes .