The rise of baleen whales
Recently discovered fossils fill important gaps in the record for whales. These show the early ancestors of ‘modern’ baleen whales.
Teeth and baleen
For a brief time in whale history, the earliest mysticete (baleen) whales had both teeth and baleen in their jaws, as with Llanocetus.
Soon after, the eomysticete whales – or ‘dawn baleen whales’ – appeared, with baleen only. This is a defining characteristic of all the later baleen whales, whether living or extinct. The group includes the largest animal that has ever lived – the blue whale.
This fossil skull of an eomysticetid whale was collected by Dr Ewan Fordyce from New Zealand rocks that formed about 26 million years ago. Broad flat upper jaw bones reveal that this whale possessed baleen only. The teeth seen in all earlier stages of whale evolution had gone.