Toothed whales start echolocating
Cotylocara and Echovenator show the ultrasonic hunting system in place within a few million years of the split.
- When
- —
- Duration
- 2 million years
- Known to
- ± 1 million years
- Era
- Oligocene, Cenozoic
Cotylocara macei, from about 28 million years ago in South Carolina, has dense bone and air-filled sinuses around the face of exactly the kind used to direct outgoing sound, and the contemporaneous Echovenator has an inner ear already tuned to ultrasound. Together they push the origin of odontocete echolocation back to the early Oligocene, close behind the split itself. The system reshapes the whole skull: the nasal passages migrate up and back, and the face becomes asymmetric to generate and aim the beam.