Around 200 million years ago, a reptile with an unbelievably long-neck roamed the region now known as Switzerland, but it had a problem. German researchers have discovered the Triassic creature kept being decapitated by its predators.
“Extreme neck elongation was a common evolutionary strategy among Mesozoic marine reptiles, occurring independently in several lineages,” Stephan Spiekman and Eudald Mujal wrote in their new paper, published in Current Biology.
“Despite its evolutionary success, such an elongate neck might have been particularly susceptible to predation.”
The genus Tanystropheus makes up a number of species of large marine reptiles (around six metres or 20 feet long) with a neck over half its total length. They’re weird looking, and distantly related to crocodiles, birds, and dinosaurs.
The two fossils the researchers looked at were different species but found in the same fossil bed in Monte San Giorgio in Switzerland. However, both also had the same fatal problem – they stopped at the neck.
“Both preserve a complete skull and an incomplete cervical column, which abruptly terminates at a distinct break in a vertebra and its associated ribs,” the researchers write.
Of course, just finding a separated head and neck doesn’t mean that predators were enjoying a neck feeding frenzy. Anything might have separated them, including decomposition after death.
But when researchers looked more closely they found clear bite marks on them – in one case right above the break. They think predators attacked at the neck, and then devoured the body.
“Only the neck and head are preserved; there is no evidence whatsoever of the rest of the animals. The necks end abruptly, indicating they were completely severed by another animal during a particularly violent event, as the presence of tooth traces evinces,” Mujal said.
“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,” he added.
The researchers suggested that only a few predators would have had enough force to be able to decapitate the reptile. Two puncture marks spaced 14.5 mm apart on the neck of one of the specimens also limited their search to just three predatory marine reptiles.
“In a very broad sense, our research once again shows that evolution is a game of trade-offs,” Spiekman says.
“The advantage of having a long neck clearly outweighed the risk of being targeted by a predator for a very long time. Even Tanystropheus itself was quite successful in evolutionary terms, living for at least 10 million years and occurring in what is now Europe, the Middle East, China, North America, and possibly South America.”