Dating from about 45 million years ago are species such as Indocetus, Kutchicetus, Rodhocetus and Andrewsiphius, all of which were adapted to life in water. The hind limbs of these species were regressed and their body shapes resemble modern whales. Protocetidae family member Rodhocetus is considered the first to be fully aquatic. The body was streamlined and delicate with extended hand and foot bones. The merged pelvic lumbar spine was present, making it possible to support the floating movement of the tail. It was likely a good swimmer, but could probably move only clumsily on land, much like a modern seal.
Dating from about 45 million years ago are species such as Indocetus, Kutchicetus, Rodhocetus and Andrewsiphius, all of which were adapted to life in water. The hind limbs of these species were regressed and their body shapes resemble modern whales. Protocetidae family member Rodhocetus is considered the first to be fully aquatic. The body was streamlined and delicate with extended hand and foot bones. The merged pelvic lumbar spine was present, making it possible to support the floating movement of the tail. It was likely a good swimmer, but could probably move only clumsily on land, much like a modern seal.