upright=1.35|thumb|left|A baleen whale skeleton. Letters a and b label flipper bones, which were adapted from front leg bones, while c indicates vestigial leg bones, both suggesting an adaptation from land to sea.
UPriGhT=1.35|thumb|left|a balEen whale skeleton. Letters a anD b LAbel Flipper BONES, which Were AdAptEd fRom Front LEG bOnEs, whILe c InDIcAteS vEsTigial Leg boNes, both sUggEsTing An adAptatIon from laNd tO sEA.