The evolution of hearing in Neoceti, with an emphasis on toothed mysticetes

This thesis investigates the hearing of toothed baleen whales, the fossil relatives of living baleen whales. Using high resolution CT imaging to see inside fossil earbones, I found that the inner ears of toothed baleen whales are similar to both early fossil whales like basilosaurids and modern baleen whales, whereas the basicranium and mandible are more similar to basilosaurids only, with significant modifications only being seen in modern baleen whales. Surprisingly, baleen whale hearing has remained relatively unchanged over the last 34 million years, being able to hear low frequency sounds prior to filter feeding, baleen and giant body size.