Compared to modern reptiles, several dinosaur-era marine reptiles had incredibly long necks. The fact that they had long necks made them more vulnerable to predators, although this was clearly a successful evolutionary strategy –something paleontologists have long speculated. Direct fossil evidence confirms this theory for the first time in the most dramatic way possible after more than 200 years of ongoing investigation.
Researchers reporting June 19 in the journal Current Biology studied the unusual necks of two Triassic species of Tanystropheus, a species of reptile distantly related to crocodiles, birds and dinosaurs. This species had unique necks composed of 13 extremely elongated vertebrae and strut ribs. As a result, these marine reptiles likely had stiff necks and were waiting to pounce on their prey. But Tanystrophe’s predators also seem to have taken advantage of the long neck for their own gain.
Careful examination of their fossilized bones now shows that the necks of two extant specimens representing different species with separate necks bear distinct bite marks, in one case right where the neck was broken. The finding offers chilling and extremely rare evidence of predator-prey interaction in the fossil record that dates back more than 240 million years, the researchers say.
“Paleontologists have speculated that these long necks form an obvious predation vulnerability, as vividly depicted almost 200 years ago in Henry de la Beche’s famous 1830 painting,” said Stephan Spiekman of the Staatliches Museum fur Naturkunde Stuttgart in Germany. “However, there was no evidence of decapitation – or any other type of attack targeting the neck – known from the abundant fossil record of long-necked marine reptiles until our current study on these two Tanystrophea specimens.”
Spiekman studied these reptiles as the main subject of his doctoral thesis at the Museum of Paleontology at the University of Zurich in Switzerland, where the specimens are housed. He recognized that two species of Tanystropheus live in the same habitat, one small species, about a meter and a half in length, probably feeding on soft-shelled animals such as shrimp, and a much larger species, up to six meters long, which feeds on fish and squid. He also found clear evidence in the shape of the skull that Tanystropheus probably spent most of its time in the water.
Two specimens of these species were well known to have well-preserved heads and necks that ended abruptly. It has been speculated that these necks were bitten, but no one has studied this in detail. In the new study, Spiekman teamed up with Eudald Mujal, also of the Stuttgart Museum, and Miquel Crusafont, a research associate at the Instituto Catala de Paleontologia in Spain, who is an expert on fossil preservation and predator interactions in the bite-based fossil record. marks on the bones. After spending an afternoon examining two specimens in Zurich, they concluded that the necks had clearly been bitten.
“Something that caught our attention is that the skull and part of the neck have been preserved undisturbed, only showing some wobble caused by the typical decomposition of a carcass in a quiet environment,” Mujal said. “Only the neck and head are preserved; there is no evidence of the rest of the animals. The necks end abruptly, suggesting that they were completely severed by another animal during a particularly violent event, as evidenced by the presence of teeth.
“The fact that the head and neck are so undisturbed suggests that when they arrived at their final burial site, the bones were still covered by soft tissues such as muscle and skin,” Mujal continued. “Apparently the predator didn’t feed them. Although speculative, it would make sense that predators were less interested in the skinny neck and small head and instead focused on the much meatier parts of the body. Together, these factors make it most likely that both individuals were decapitated during hunting and were not caught, although with fossils this old, extirpation can never be completely ruled out.”
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