These Prehistoric Dolphins Had Tusk-Like Teeth

The animals likely thrashed their heads back and forth to injure or stun prey with their unusual, horizontal teeth

Ancient dolphins with tusk-like teeth
Nihohae matakoi swam in waters off the coast of New Zealand around 25 million years ago. Daniel Verhelst

Scientists have discovered a new species of prehistoric dolphin with strange, tusk-like teeth that have never been seen in living cetaceans. The odd-looking creature swam the waters off the coast of New Zealand around 25 million years ago. 

Unlike modern dolphins, which typically have small, conical teeth protruding vertically in their mouths, the skull had several long teeth extending horizontally out of the end of its snout. 

“Mentally, I just couldn’t figure out what could possibly need teeth like that,” Ambre Coste, a paleobiologist and marine biologist at the University of Otago in New Zealand, tells the New York Times’ Jack Tamisiea.

But eventually, the team came up with a theory: To use these teeth, the dolphin might have practiced “a new feeding method not previously described in marine mammals,” Coste tells Newsweek’s Aristos Georgiou. “We suggest that it would have rapidly swung its head from side to side to injure or stun prey, making them easier to catch and eat.”

Originally collected in 1998 in southern New Zealand’s Awamoko Valley, the skull sat for years in the University of Otago Geology Museum’s collections before scientists described it. Now, in a new study published Wednesday in Proceedings of the Royal Society B, Coste and her colleagues name the dolphin Nihohae matakoi. Nihohae is a combination of Niho, the Māori word for “teeth,” and Hae, the word for “slashing.” The species name is a combination of “Mata,” which means face or point, and “Koi” for sharp. 

Because of the way Nihohae’s teeth were positioned, they lay “too flat relative to each other to be able to pierce or grasp/trap prey,” per the study. So, to determine how Nihohae may have used its teeth, the researchers examined them for signs of wear under a scanning electron microscope. The teeth had no scratch marks on the enamel, which suggested they weren’t used to sift through sand or other rough material in search of prey. And their delicate nature indicated the teeth did not play a role in combat with other dolphins or fending off predators. 

“Given that the teeth in Nihohae are splayed out to the side, that’s pretty good indication that there was lateral movement similar to the sweeping of a sawfish snout,” Robert Boessenecker, a paleontologist at the College of Charleston who was not involved in the study, tells the Times.

In reality, the prehistoric dolphin’s teeth aren’t tusks—true tusks are continuously growing front teeth with no root. Nihohae’s teeth, on the other hand, were rooted and couldn’t grow endlessly. Today, the only living cetaceans with tusks are narwhals—their iconic “horn” is really a constantly growing canine tooth. 

Nihohae was probably around six feet in length, with a longer neck than modern dolphins and paddle-like front fins, per Newsweek. The dolphin’s neck bones were unfused, which would have allowed for a wider range of sweeping motion. And its long, flattened face would have been perfect for back-and-forth head movements, per a statement. Once Nihohae impaled its small, soft-bodied prey, it likely swallowed the animal whole.

“You can just imagine these dolphins swimming up to a shoal of squid and wildly thrashing their heads back and forth,” Coste tells the Times.

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