Back to the mammal skulls, this time featuring a seal and a sea lion, respectively. What's the difference? Apparently, different evolutionary lineages, and different resulting features. The characteristic that I always remember is that seals don't have external ears, whereas sea lions have little ear flaps. They move differently on land too: seal lions use their flippers to get about (and their front flippers are bigger than seals') whereas seals sort of slide/flop along, inchworm-like perhaps.