Ancient reptiles’ long necks made them vulnerable to decapitation

Fossils of two Triassic reptiles present severed heads and necks with chunk marks, highlighting a downside of the extraordinarily lengthy necks frequent to many historical sea creatures.

“We provide the first tangible proof that this body plan was, at least in some animals, a weak spot,” says Eudald Mujal on the Stuttgart State Museum of Natural History in Germany.

Tanystropheus, a genus of reptiles that lived within the Triassic Period, 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 ground.

Mujal and his colleague Stephan Spiekman, additionally on the Stuttgart museum, used high-resolution pictures and 3D modelling to evaluate the fossils of two species, Tanystropheus hydroides and Tanystropheus longobardicus, on show on the University 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. Both necks had a number of chunk marks, together with one which confirmed the telltale indicators of a break brought on by a violent affect, 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 one specimen, a predator appeared to have bitten into the bone after which pulled again. The bites have been to date beneath the pinnacle 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 have been more likely to have been decapitated by different species of marine reptile, in all probability Nothosaurus giganteus, Cymbospondylus buchseri or Helveticosaurus zollingeri.

While the aim of Tanystropheus’s elongated neck continues 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 think it just sat there and waited for its prey to come to it – which is something modern crocodilians do as well,” he says. It was unlikely to assist the animals breathe floor air whereas staying deep underwater, as stress variations would make the respiratory inefficient, he provides.

The findings recommend that the evolutionary benefit of the lengthy neck got here, paradoxically, with the danger of the animals shedding their very own heads by predator assaults, the researchers say. Even so, that threat didn’t outweigh the advantages, because the long-necked physique plan was “very, very successful” – lasting 175 million years and occurring all through the traditional world, says Mujal.