The Discovery Of A New Type Of Whale Suggests These Giant Sea Mammals Have been Around Longer Than We Thought

An artistic reconstruction of the 28 million-year-old Cotylocara macei as it patrolled the shallows near present-day Charleston, South Carolina. Image: Carl Buell

The discovery of a fossil of a previously unknown type of whale which lived about 28 million years ago suggests that these toothed mammals evolved early than thought.

The find, announced in the journal Nature, suggests that echolocation, the use of a sonar-like ability, evolved extremely early in the divergence of toothed whales — sperm whales, killer whales and dolphins — from their common ancestor with baleen whales.

The evolutionary adaptation of echolocation provided a way for species living in dark and murky water to navigate and hunt prey.

Echolocation is a distinctive feature of toothed whales (odontocetes), but little is known about how and when this complex behaviour and its underlying anatomy evolved.

Dr Jonathan Geisler of the New York Institute of Technology College of Osteopathic Medicine and colleagues describe a fossilized toothed whale from the Oligocene of South Carolina.

The animal’s skull has several features suggestive of a rudimentary form of echolocation, including cranial asymmetry and a dense upper jaw.

Caption: The skull of the 28-million-year-old Cotylocara macei. Its anatomy and density variation indicate that this early toothed whale used echolocation to find its prey. Image: James Carew and Mitchell Colgan

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