What are some common traits of the earliest whale ancestors?

The earliest whale ancestors, known as cetaceans, exhibited several common traits that link them to land-dwelling mammals. They had elongated bodies, limbs modified into flippers, and nostrils positioned on the top of their heads, which facilitated breathing while swimming. Additionally, they retained some characteristics of terrestrial mammals, such as a robust skeletal structure and a hip structure that indicated they were still somewhat adapted to land. These traits highlight their evolutionary transition from land to an aquatic lifestyle.