Final answer:
Ancient whales likely had varied teeth suited for their aquatic diets, similar to how modern sharks have different teeth based on their prey. They may have been diphyodonts, with baby teeth replaced by permanent ones over time.
Step-by-step explanation:
Ancient whales, such as Pakicetus and Rodhocetus, are believed to be ancestors of modern whales. Over time, they transitioned from land to aquatic environments. As they evolved, the structure of their teeth adapted to their new diets in the aquatic ecosystem. While not much detail was provided about the specific teeth of ancient whales, we know that the teeth of marine animals evolve based on their diet. For example, modern sharks show a variety of teeth shapes based on their prey. This suggests that ancient whales may also have had different types of teeth suited for their diet, possibly with variations such as pointed teeth for gripping fish or flattened teeth for crushing mollusks. However, unlike sharks, which can shed and replace many teeth, mammals including ancient whales were possibly diphyodonts, having a set of baby teeth replaced by permanent teeth.