Basilosaurus cetoides

Basilosaurus cetoides, an extinct genus of large, predatory cetaceans that lived during the late Eocene epoch around 40 to 34 million years ago, is notable for its elongated, serpentine body, which reached lengths of up to 18 meters, a characteristic that sets it apart from modern whales, and its well-developed, yet vestigial hind limbs, suggesting a transitional form between land-dwelling ancestors and fully aquatic organisms; it is believed to have inhabited warm, shallow seas and preyed on smaller marine animals, such as fish and other marine vertebrates, using its sharp teeth and powerful jaws, while also being one of the first cetaceans to exhibit fully developed tail flukes for propulsion in the water, signaling a significant step in the evolutionary path of modern whales.