Artist’s impression of the Triassic reptile Tanystropheus hydroides being decapitated by a predator
Roc Olivé (Institut Català de Paleontologia Miquel Crusafont)/FECYT
Fossils of two Triassic reptiles present severed heads and necks with chunk marks, highlighting a downside of the extraordinarily lengthy necks widespread to many historic sea creatures.
“We offer the primary tangible proof that this physique plan was, at the least in some animals, a weak spot,” says Eudald Mujal on the Stuttgart State Museum of Pure Historical past in Germany.
Tanystropheus, a genus of reptiles that lived within the Triassic Interval, had stiff necks as much as 2 metres lengthy which will have allowed them to seize fish and different animals with their crocodile-like heads whereas protecting their our bodies much less seen on the ocean flooring.
Mujal and his colleague Stephan Spiekman, additionally on the Stuttgart museum, used high-resolution images and 3D modelling to evaluate the fossils of two species, Tanystropheus hydroides and Tanystropheus longobardicus, on show on the College of Zurich, Switzerland.
The 242-million-year-old specimens included two full, well-preserved skulls and two equally well-preserved, however abruptly shortened spines – with one animal having solely 10 of its 13 neck vertebrae, and the opposite solely seven. Each necks had a number of chunk marks, together with one which confirmed the telltale indicators of a break attributable to a violent influence, the researchers say.
Traces of enamel in each specimens reveal {that a} predator attacked from behind and above, crushing and fully severing the neck. In a single specimen, a predator appeared to have bitten into the bone after which pulled again. The bites had been to date under the top that the animals in all probability didn’t see their attackers coming, says Mujal.
Combining clues from the animals’ marine habitats close to what’s now the Swiss-Italian border and the sorts of tooth marks on their bones, the researchers concluded that the long-necked reptiles had been prone to have been decapitated by different species of marine reptile, in all probability Nothosaurus giganteus, Cymbospondylus buchseri or Helveticosaurus zollingeri.
Whereas the aim of Tanystropheus’s elongated neck remains to be unclear, Spiekman says it could have lifted the reptile’s head excessive above its physique, giving it entry to unsuspecting fish and different marine animals. “We expect it simply sat there and waited for its prey to come back to it – which is one thing fashionable crocodilians do as effectively,” he says. It was unlikely to assist the animals breathe floor air whereas staying deep underwater, as strain variations would make the respiration inefficient, he provides.
The findings counsel that the evolutionary benefit of the lengthy neck got here, paradoxically, with the danger of the animals dropping their very own heads by way of predator assaults, the researchers say. Even so, that threat didn’t outweigh the advantages, because the long-necked physique plan was “very, very profitable” – lasting 175 million years and occurring all through the traditional world, says Mujal.
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