Ambulocetus, the walking whale
A crocodile-shaped mammal with huge feet hunts in estuaries — halfway to the sea, and looking it.
- When
- —
- Duration
- 1 million years
- Known to
- ± 1 million years
- Era
- Eocene, Cenozoic
Ambulocetus natans, the walking whale that swims, is the transitional fossil in the sequence that most obviously looks the part: a metre-long skull, short powerful limbs with large feet, and a body built for undulating propulsion rather than running. Oxygen isotopes in its teeth indicate it moved between fresh and salt water, exactly what an estuarine ambush predator would do. It was found in 1994, and it converted whale origins from a textbook inference into a documented series.