For a movie about a giant, ravenous shark, I expected there to be a lot more chomping in The Meg. Perhaps the movie’s titular Otodus megalodon got so full chewing through the cast that by time it arrived at the crowded beach at the pic’s climax, the predator just didn’t have much stomach for tourists. But among the morsels the megatoothed shark does enjoy during its trip down the buffet line is a pair of whales that had the misfortune to be hanging around a beleaguered sea station. This fits the expected behavior of the actual megatoothed shark - in books and on basic cable, Otodus megalodon is often shown feasting on blubber - but, as we so often ask in paleo, how do we know?
The fossil record of Otodus megalodon and related sharks is primarily one of teeth and a few vertebrae. What we know of the shark’s size, growth, and biology comes from these limited resources. We also know that there was a whole buffet of marine mammals during the long run of this enormous shark, and such high-energy food sources would have been critical for the predator’s physiological demands. And then there are the bitten bones.
These fossils are relatively rare. They are the remains of cetaceans that were bitten by sharks long ago, and it can be difficult to determine whether they represent hunting or scavenging. Still, traces like these can give us just that much more insight into the habits of the impressive megatooth sharks, with bitten bones described by paleontologist Stephen Godfrey and colleagues being the latest example to make its way into the academic record.
The bones in question were not found together, but collected separately from sites in North Carolina and Maryland. Each of the trio came from seas where megatooth sharks were the apex predators, spanning 23 to 2.5 million years ago. And, significantly for the behavioral implications of the bites, the bones all came from near the end of the tails of ancient whales.
It’s difficult to tell exactly which species of shark did the biting. There are two prime candidates - the rock star Otodus megalodon or its relative Carcharocles chubutensis. Both had teeth the right size and shape to leave the cut patterns on the bones. In fact, some of the markings appear to have been made when the bones became wedged between neighboring teeth in the sharks’ mouths, helping narrow down the size of the fish doing the biting.
None of the three bones show signs of healing. Either the whales were killed by the sharks, or the sharks were scavenging. But Godfrey and colleagues propose that predation is more likely based on where the bite marks occur.
Even though modern great white sharks will scavenge on carcasses of whales larger than themselves, the researchers point out, these sharks actively prey on smaller marine mammals and often will often attack from below and behind. Taking out the tail of dolphins, for example, appears to be a regular strategy. So, turning back to the fossil whales, the bitten cetaceans were considerably smaller than the megatooth sharks - about 13 feet long compared to megatooth sharks that could be 36 feet long or more. Perhaps the bite marks are signs of a common hunting strategy, trying to take out the propulsion of the whales and cause blood loss in an initial strike. Each bitten bone might be a testament to a sudden, traumatic moment where one ancient life gave way to another.