With evolution there’s always a trade-off – long necks may help you find food but they’re also a massive weak spot. Now, paleontologists have found direct fossil evidence of prehistoric, long-necked marine reptiles being decapitated by predators.
While dinosaurs ruled the land, marine reptiles prowled the seas. Many of these sported long necks, most famously the plesiosaurs, which are the beasts you probably picture when you think of the Loch Ness monster. But while these necks might have given the animals an advantage against their own prey – usually fish or squid – they probably would have looked pretty inviting to predators. Now paleontologists have found fossil evidence to support this long-held assumption.
Tanystropheus was a marine reptile that lived across what’s now Europe, Asia and North America during the Triassic Period, about 240 million years ago. It measured up to 6 m (20 ft) long, and half of that length was taken up by its neck. Rather than being made up by lots of little vertebrae, the bones in that neck were very long, meaning it would have been pretty stiff – and probably a great target for hungry hunters to chomp down on.
But did that ever actually happen? Researchers at the State Museum of Natural History Stuttgart wanted to find out, so they investigated two specimens in the museum’s collection, where just the heads and necks had been preserved without bodies. That alone doesn’t indicate decapitation – its common for only some parts of skeletons to fossilize.
But when the team looked closely at the ends of the necks, they found tooth marks on the bones, some of which were also crushed in a way that suggested a single bite. Intriguingly, the heads and upper necks remained well-preserved, which indicates they were still covered in muscle and skin when they were buried. That might give us a glimpse into the feeding behaviors of these ancient animals.
“They were clearly not fed on by the predator,” said Eudald Mujal, an author of the study. “Although this is speculative, it would make sense that the predators were less interested in the skinny neck and small head, and instead focused on the much meatier parts of the body. Taken together, these factors make it most likely that both individuals were decapitated during the hunt and not scavenged, although scavenging can never be fully excluded in fossils that are this old.”
Having found two examples already, the researchers say that it was probably common for predators to bite off the heads and necks of marine reptiles with long necks. But even with this weakness, the trade-off still seems to have been worth it. The trait evolved several times – after all, Tanystropheus isn’t closely related to plesiosaurs, despite the similarities – and these creatures persisted for hundreds of millions of years.
The research was published in the journal Current Biology.
Source: State Museum of Natural History Stuttgart