A sperm whale from millions of years ago was attacked by a massive predatory shark. This shark, possibly Otodus megalodon, or its ancestor Otodus chubutensis in North Carolina, is what caused the attack.
Researchers said that marks from the attack preserved in gouges made of the sperm Whale's tooth are the first fossil evidence that megatoothed sharks engaged in sperm whale tussling.
Stephen Godfrey (curator of paleontology at Calvert Marine Museum, Solomons, Maryland), said in an email that "it would seem these giant sharks were preying upon whatever they wanted to" and that no marine animal was immune from attacks by these giant sharks.
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One tooth is all that remains of the ancient Sperm Whale. Norman Riker, a co-researcher from Dowell in Maryland, discovered the tooth in what is now the Nutrien Aurora Phosphate Mine. This was a large phosphate mining operation in Aurora, North Carolina in the 1970s and 1980s when it was open for fossil collectors.
The museum newsletter reported that Riker, who donated the tooth the Calvert Marine Museum, had died in January 2021 at the age of 80.
Researchers are not sure when the shark-whale brawl took place. Godfrey stated that mine workers removed large quantities of sedimentary rock from the surface to reach older, phosphate-rich bedrock. They then dumped them nearby for fossil hunters.
Scientists don't know whether the tooth is from one of two rock layers that have been laid over time. This would date the tooth to the Miocene Epoch, approximately 14 million years ago. Or the younger fossils bed, which would date the tooth to the Pliocene Epoch, 5 million years back.
He noted that the tooth fell into the Neogene Period (23 million to 2.5million years ago).
The Earth's climate was warmer during the Neogene. As a result, there was less ice at the North and South Poles, which led to higher sea levels. Godfrey stated that "coastal North Carolina was covered with a large shallow arm of Atlantic Ocean." "These waters were teemed in abundant marine life."
(Godfrey et al., Acta Palaeontologica Polonica, 2021)
Above: An ancient sperm whale tooth shows three gouge marks left by the megatoothed Shark at various angles.
Shark versus Whale
Godfrey stated that the tooth's curved length of 4.5 inches (11.6 cm) clearly indicate its origins as an extinct species of sperm whale.
Researchers used an equation to compare extinct sperm whale teeth size and body size to estimate that this whale was only 13 feet (4 meter) in length. Godfrey said that today's sperm-whale can grow to over 50 feet (15 meters) in length.
The three gouge marks that are visible on the tooth indicate that whatever took a bite of it had perfectly spaced, serrated teeth.
The researchers discovered that the only two possible culprits were O. chubutensis, a megatoothed shark that lived 28 million to 13,000,000 years ago, and O. megalodon, its descendant which existed 20 million to 3.5 millions years ago.
Godfrey sent the email stating that none of the fossil sharks from the phosphate mining have teeth large enough or serrations sufficiently to have left these bite marks on the sperm whale teeth.
"Bite traces left by these huge sharks (with a body size of over 60 feet [18m]) have been found on bones of extinct whales or dolphins but not on the heads or other bones a sperm whale.
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The team stated that it is possible that the megatoothed shark was trying to find sperm whales that have died, but it is more likely that those gouge marks were made in a predatory attack. The cut marks were on the root of a tooth or the part that was embedded into the whale's jaw.
Godfrey stated that "So before the megatoothed tooth shark could cut into sperm whale teeth, it first had to slice through the jaw bone holding the tooth," Godfrey explained.
It would be unlikely for a large shark to target the jaws or seafloor carcass of an sperm whale. He said that there would be very little flesh to return the effort.
The bite marks are intended to indicate an attack on the head, with the aim of inflicting a fatal wound. This means that a giant shark may be biting your head to try and kill you.
The attack might have been successful. (Tim Scheirer)
According to Alberto Collareta (paleontologist at the University of Pisa in Italy), the findings shed light onto the North Carolina's ancient ecology. He was not part of the study.
He said that it was not surprising that the megatoothed Shark bit the sperm Whale's tooth. Killer whales are the most powerful predators of today's oceans. They love to eat the fleshy tongues and blubbery throats other whales.
Collareta said that the megatoothed shark attracted to the sperm whales because they had some fat reserves.
The study was published online in Acta Palaeontologica Polonica on Aug. 9.
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Live Science originally published this article. You can read the original article here.
