The waters off New Zealand 25 million years in the past had been residence to early baleen whales, megatooth sharks and human-size penguins. Now researchers are including a weird dolphin to the combo that will have used tusklike enamel to thrash prey into submission.

The dolphin’s almost full cranium was collected in 1998, from a cliff facet within the Otago area of New Zealand’s South Island. The specimen ended up within the University of Otago Geology Museum’s assortment. Two many years later, Amber Coste, who was finishing her Ph.D. in paleontology, stumbled upon the unusual cranium.

“Mentally, I just couldn’t figure out what could possibly need teeth like that,” Dr. Coste stated.

The fossil dolphin’s dentition was in contrast to something seen in dwelling cetaceans. While trendy dolphins are armed with a snoutful of cone-shaped enamel completely calibrated to snap up fish, this creature possessed a number of giant enamel that protruded out of the top of its snout. Instead of tapering downward into fangs, these enamel had been splayed out horizontally just like the blade of a spade.

In a paper printed Wednesday within the journal Proceedings of the Royal Society B, Dr. Coste and her colleagues described the snaggletoothed dolphin as a singular species, Nihohae matakoi. The curious cetacean’s genus, Nihohae, is a mixture of the Maori phrases for “teeth” and “slashing.”

True tusks are outlined as frequently rising enamel that stick out of the mouth, and narwhals are the one dwelling cetaceans which have them. Nihohae’s protruding enamel had been deeply rooted in its cranium, which restricted their means to proceed rising over the animal’s lifetime. As a outcome, Nihohae’s enamel are extra much like the tusklike projections on the decrease jaws of male beaked whales, which use these enamel to tussle over females.

To decide how Nihohae wielded its tusklike enamel, Dr. Coste and her colleagues examined a number of of the enamel underneath a scanning electron microscope. Surprisingly, the researchers discovered little proof of wear and tear on them.

This meant it was unlikely that Nihohae used its tusklike enamel to battle rivals for mates. It additionally solid doubt on one other speculation that Nihohae used its enamel to sift via the sandy seafloor for prey. “Sand is really abrasive and will absolutely trash your teeth, but there’s literally no scratches on these teeth,” Dr. Coste stated.

The enamel’s horizontal orientation additionally made them a poor instrument for snagging prey. While the enamel of different fossil dolphins interlocked to lure fish inside, Nihohae’s splayed-out enamel wouldn’t have been helpful for that process. They had been additionally almost flat, so Nihohae would have had a troublesome time biting into something.

Because no different dolphin possessed enamel like Nihohae’s, the researchers scoured the remainder of the animal kingdom for related anatomy. This led them to sawfish, which swipe their tooth-studded saws to both injure or stun prey earlier than vacuuming it up complete.

Dr. Coste and her colleagues hypothesize that Nihohae, whose unfused vertebrae in all probability allowed for a broad vary of neck motion, hunted in an identical manner, swinging its head to skewer or stun squid and different soft-bodied sea creatures. Then it could swallow the staggered prey complete.

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

This searching type appears believable, based on Robert Boessenecker, a paleontologist on the College of Charleston in South Carolina who was not concerned within the new examine.

“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,” stated Dr. Boessenecker, who has studied different toothy dolphin fossils from each South Carolina and New Zealand.

Dr. Coste hopes that additional examination of Nihohae’s tusklike enamel and future fossil finds will shed further mild on the variety of historical dolphin searching methods.