The Calvert Marine Museum recently named a new species of extinct dolphin and published a paper about a whale tooth that had been bitten by a Megalodon.

Ron Ison found the partial skull of a never-before-seen dolphin while scuba diving in the Merrin River in North Carolina. The dolphin, which is closely related to the Amazon River dolphin, would have lived in the ocean in prehistoric times.

Ison donated his find to the Calvert Marine Museum, which recently named the new species Isoninia borealis in his honor in the Fossil Record, an open-access paleontological journal of the Museum für Naturkunde Berlin). The genus name is a combination of Ison, the family name of Ron Ison, and Inia, the epithet of the Amazon River dolphin (Inia geoffrensis). The species name “borealis” is Latin for “northern,” a reference to the only known specimen having been found in the Northern Hemisphere.

The new dolphin was named in a recently published paper.

“It is a one-of-a-kind [find],” Calvert Marine Museum Curator of Paleontology Stephen Godfrey said in a news release. “Of the millions of individuals of this species that ever lived, this is the only known specimen.”

There are three closely-related species of modern dolphins that exclusively inhabit river basins in South America: Inia geoffrensis found within the Orinoco and Amazon River basins, Inia boliviensis that inhabit the Beni–Mamoré River Basin, and possibly Inia araguaiaensis from the Araguaia–Tocantins River Basin. The ancestors of these modern-day river dolphins were oceanic dolphins.

What the new dolphin skull demonstrates is that during the Miocene epoch — which occurred 6 to 7 million years ago — some relatives of the Amazon River dolphins were oceanic and far-removed from South America.

Battle of the giants

Years ago, fossil enthusiast Norm Riker found a sperm whale tooth in the fossil-rich Aurora Phosphate Mine in North Carolina, which he donated to the Calvert Marine Museum.

Recently John Nance, a paleontology collections manager at the museum, discovered large shark bite marks on the tooth. Bite marks from a megatoothed shark, like megalodon, have been found on another raptorial macro-predator, a sperm whale, a first for the fossil record.

“I noticed the large sperm whale tooth while processing the thousands of fossils donated by Norm,” Nance said in a news release. “After picking up the tooth I saw the serrated scrapes on it and brought it to Stephen’s attention, realizing it was an important fossil.”

A description of the find was recently published in the journal Acta Palaeontologica Polonica.

The tooth shows three gouges, one of which also preserves raking bite traces, made as the serrations on the giant shark tooth struck and cut into its surface. Godfrey said he and his staff do not know if these bite traces came about as a result of scavenging or active predation. However, bite traces on part of the skull suggests a live predatory interaction, instead of just scavenging by the shark.

The tooth marks the first evidence in the fossil record of a possible predatory/antagonistic interaction between a sperm whale and a megatoothed shark. In addition, the bite traces occur on part of the root that was originally embedded in the sperm whale’s jaw. In order for the shark teeth to have marked the sperm whale tooth, the teeth would first have had to cut/break through the whale’s jaw bone, which suggests a powerful bite on the part of the shark.

According to the news release, it is unlikely that a large shark would target the jaws of a floating or seafloor carcass of a sperm whale as there would be little flesh in return for the effort by the mega-toothed shark. The bite traces suggest a live antagonistic interaction and hint at an attack to the head of the sperm whale with the goal of inflicting a mortal wound.

The release also stated that this kind of an attack to the skull contrasts with the strategies used by modern large sharks to attack small, echolocating toothed whales (like dolphins).

Based on where it was found, the tooth could be between 6 and 18 million years old.

For more about the Calvert Marine Museum and its collections, visit www.calvertmarinemuseum.com/.