240-Million-Year-Old Long-Necked Reptiles Were Decapitated by Predators

As if the age of the dinosaurs wasn't terrifying enough, scientists have now found evidence that long-necked marine reptiles were brutally decapitated by predators.

According to a paper published on June 19 in the journal Current Biology, fossils of the head and neck from two species of Tanystropheus dated to the Triassic period, around 240 million years ago, have been found with clear bite marks on them.

"For a long time, it was already known that the two specimens of Tanystropheus that we studied, one belonging to a large species of Tanystropheus and the other to a much smaller species, were represented by a well-preserved head and a neck that abruptly ended. It was sometimes speculated that these necks were bitten off by predators, but this was never investigated in detail," Stephan Spiekman, a Triassic reptile evolution researcher at the Staatliches Museum für Naturkunde Stuttgart in Germany and co-author of the paper, told Newsweek.

"[We] found clear bite marks in both specimens, formed by clear punctures of the bone in an outline that corresponds to the teeth of predators, as well as grooves that were caused by teeth scratching over the bone surface. Back in Stuttgart, [we] closely analyzed their data and confirmed that the necks were bitten off in both specimens, representing the first clear example of decapitation in a long-necked marine reptile."

Spiekman explains that the reason that these creatures' predators went for the neck was because this was one of the most vulnerable parts of their bodies.

"We see the same basic pattern in both individuals: they are bitten on the back half of their necks, but still in front of the thicker base of the neck where it attaches to the torso. This was likely the thinnest part of the neck and far away from the head, and therefore a particularly vulnerable spot. Of course, with only two examples, we can't say for certain that this was a deliberate hunting strategy for the predators, but it is very much possible and would have made sense," he said.

Additionally, it is likely that the reason the necks and heads were found was because they were not eaten by the predator, being discarded in favor of the tastier morsels of the prey.

"We think the predators did not eat the head and neck in both cases simply because there would have been relatively little meat on those body parts. The rest of the skeleton is not preserved, and it is very possible that was the part the predators fed on, because the torso and limbs were the main source of meat. Reptiles cannot chew, so they likely would have ripped up the body and swallowed the meatiest parts whole," Spiekman said.

This finding implies that having a long neck was a weakness for species of reptiles living in the ocean at this time. However, this wasn't necessarily the case for all long-necked species, such as plesiosaurs, which may have been more hardy to attack than the unfortunate Tanystropheus species.

"Long-necks evolved many times, and the long-necked plesiosaurs (the flippered marine reptiles, think the Loch Ness Monster) and Tanystropheus are quite different beasts. The plesiosaurs were cruising through the oceans, they were really well adapted to ocean life. Modern research also suggests that their long necks were perhaps covered by thick layers of muscle and fat, which would have made them more hydrodynamic. Their neck bones are also quite sturdy," Spiekman said.

Tanystropheus, on the other hand, had extremely long and thin neck vertebrae that were internally hollow. These slender and lightweight neck bones were therefore much more vulnerable to the snapping jaws of their predators.

"So, considering all of this, the fact that the necks of Tanystropheus were targeted does not necessarily imply this was also a problem for plesiosaurs. In fact, many more fossils of plesiosaurs are known, hundreds of them, and none of them show unambiguous evidence that the neck was attacked. We don't know for certain if this means that the plesiosaurs were not attacked on their necks, or whether their necks were still targeted, but bites simply did not penetrate to the bone because they were so thick. It's something we might want to investigate in the future," Spiekman said.

Having a long neck, therefore, wasn't automatically an evolutionary dead end, and may have been very beneficial to animals that escaped the jaws of their predators.

"It's hard to imagine the use of such a long neck through modern eyes, because, as long as you don't believe in the Loch Ness legend, there's nothing alive today that even remotely resembles the long-necked reptiles of the Mesozoic. However, long-necked marine reptiles were a remarkable evolutionary success story," Spiekman said.

Different forms of long-necked marine reptiles were very common across a period of around 175 million years. For comparison, there have only been 66 million years between our lives and when the T. rex roamed.

"Although the neck was vulnerable to attack by predators in Tanystropheus, this was likely not enough to drive them away from this evolutionary system. So what were these necks for? They almost certainly helped these animals catch their food. And they were actually surprisingly versatile. Even in Tanystropheus alone, the large species ate fish and squid, whereas the small species ate shrimp and other small invertebrates. In plesiosaurs too, we know of species that were focused on catching fish, and others that were specialized for catching food from the seafloor," Spiekman said.

"Likely the long neck helped these animals reach their prey, and it also would have helped them stay hidden. You have to remember that water is almost always murky to some extent, and having a relatively small head on a very long neck means that the head can only be seen when it's already too late for the prey."

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