Nature
PUBLISHED
Being top of the food chain doesn't mean you'll get shown any respect after you die. A 25-million-year-old giant shark almost twice as big as today's largest great white was feasted upon by smaller sharks, a new discovery has revealed.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.Amateur paleontologist Philip Mullaly revealed one of the most remarkable shark fossils ever found when he noticed part of a 7-centimeter (3-inch) shark tooth in a boulder on his local beach.
The tooth came from a great jagged narrow-toothed shark (Carcharocles angustidens), a massive prehistoric shark that grew to an epic 9 meters (30 feet) long and fed on small to medium-sized whales. The strata in the rock in which the tooth was encased places it at 25 million years old.
Angustidens teeth have usually been found individually, reflecting the fact that, like modern sharks, they dropped teeth frequently and grew new ones.
However, when Museums Victoria paleontologists Dr Erich Fitzgerald and Tim Ziegler examined the site along Australia’s Great Ocean Road they found more than 40 teeth. Most showed strong evidence of coming from a single individual. Fitzgerald explained to IFLScience that no narrow-toothed shark teeth were duplicated, as would be expected if they came from multiple sharks, all matched in size, and some were even located together as they would have been in the shark’s mouth.
In other words, these were not stray teeth shed while feeding, but the entire set from a C. angustidens. A handful, however, came from smaller sharks belonging to the Hexanchus (Sixgill) family. Fitzgerald told IFLScience there is sufficient evidence to prove these came from at least two different individuals.
The team concluded multiple Hexanchus sharks feasted on the mega shark's carcass, dropping teeth in the process. “The teeth of the sixgill shark work like a crosscut saw, and tore into the Carcharocles angustidens like loggers felling a tree. The stench of blood and decaying flesh would have drawn scavengers from far around,” said Ziegler in a statement.
An alternative theory, where the giant ate several smaller sharks shortly before dying, doesn't match the absence of digestive wear on the smaller sharks' teeth.
The work has yet to be published, as Fitzgerald hopes erosion will reveal more of the grisly scene. However, the finds are on display in the museum.
Fitzgerald told IFLScience the events came towards the end of angustidens’ reign, but its ecological niche was inherited by a related species of similar size. A few million years later the even larger Carcharocles megalodon, or Meg, took over the whale-eating role, only to disappear around 3.5 million years ago as mid-sized baleen whales turned into modern giants.
