What type of skeletal changes occurred in a whales evolution?

Whales underwent significant skeletal changes during their evolution from land-dwelling ancestors to fully aquatic mammals. Key adaptations include the reduction of hind limbs, which are largely vestigial, and the modification of forelimbs into flippers, enhancing swimming efficiency. Additionally, their skulls evolved to become elongated and streamlined, with nostrils shifting to the top of the head to facilitate breathing at the water's surface. Overall, these changes reflect a transition to a fully marine lifestyle, optimizing their anatomy for life in water.