Even though the evolution of long necks with this species had downsides, other marine reptile species also had long necks, and continued on that evolutionary tract for 175 million years.
Fossil evidence has shown that marine reptiles that were built with very long necks suffered from decapitation by predators. Researchers Stephan Spiekman and Eudald Mujal of the Staatliches Museum für Naturkunde Stuttgart, Germany, and the Institut Català de Paleontologia Miquel Crusafont, Spain, studied the fossilized necks of two Triassic era species of Tanystropheus, a reptile that is most closely related to crocodilians, birds and dinosaurs and found that the necks were severed with clear bite marks on them, indicating that the Tanystropheus necks made them easy prey for the predators who hunted them.
“Paleontologists speculated that these long necks formed an obvious weak spot for predation, as was already vividly depicted almost 200 years ago in a famous painting by Henry de la Beche from 1830,” Stephan Spiekman of the Staatliches Museum für Naturkunde Stuttgart, Germany said in a statement released by Cell Press. “Nevertheless, there was no evidence of decapitation—or any other sort of attack targeting the neck—known from the abundant fossil record of long-necked marine reptiles until our present study on these two specimens of Tanystropheus.”
The study of these reptiles were the main focus for Spiekman’s doctoral work at the Paleontological Museum of the University of Zurich, Switzerland. The two fossilized severed necks are housed at the museum. Spiekman’s work shows that the two Tanystropheus species differ in size, with one being about 1.5 meters in length and fed on shrimp and other soft shelled invertebrates, while the larger specimen measured at six meters in length and likely fed on fish and squid. Both spent the majority of their time in water.
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Spiekman and co-author Eudald Mujal, an expert on predatory interactions in the fossil record, concluded that the necks were bitten off by a larger predator.
“The fact that the head and neck are so undisturbed suggests that when they reached the place of their final burial, the bones were still covered by soft tissues like muscle and skin,” Mujal continued. “They were clearly not fed on by the predator. 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.”
The researchers note that even though the evolution of long necks with this species had downsides, other marine reptile species also had long necks, and continued on that evolutionary tract for 175 million years.
“In a very broad sense, our research once again shows that evolution is a game of trade-offs,” Spiekman said in the statement. “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.”
The title of the research paper is “Decapitation in the long-necked reptile Tanystropheus (Archosauromorpha, Tanystropheidae), Current Biology (2023).”
