Ancient tracks may record stampede of turtles disturbed by earthquake

Strange impressions in a rock face in Italy may have been left by a stampede of sea turtles disturbed by an earthquake around 83 million years ago.

Free climbers discovered the unusual features in an area that is off limits to the public on the slopes of Monte Cònero on Italy’s east coast.

There are more than 1000 prints in two locations – one more than 100 metres above the ocean, and a second shelf that has fallen to La Vela beach. These rocks consist of limestone that formed from fine sediment on a shallow seabed in the Cretaceous period.

The climbers took photos that were later shown to Alessandro Montanari at the Geological Observatory of Coldigioco in Italy and his colleagues. The scientists then gained permission from the managers of the Cònero Regional Park to survey the area on foot and with drones.

Montanari says it is impossible to be certain what animals made the markings, but only two groups of vertebrates inhabited the oceans at the time – fish and marine reptiles. The team ruled out fish, plesiosaurs and mosasaurs, leaving sea turtles as the most likely candidates.

Because the seafloor is such a dynamic and soft environment, for the prints to be preserved, they would have had to be buried almost instantly after they were made – which could have happened during an earthquake.

“[It may have been] a strong earthquake, which scared the bejesus out of these poor animals who were peacefully hanging around the nutrient-rich shallow water environment,” Montanari says.

“They all swim in panic towards the open sea on the west of the reef, and some of them reached the oozy seafloor, leaving their paddle prints.”

However, the sea turtle stampede is just a hypothesis and the team now hopes to involve specialist ichnologists, who study trace fossils such as trackways, for the next stage of research.

Anthony Romilio at the University of Queensland in Australia says if the markings are sea turtle traces, they would “easily be the most numerous in the world”.

However, without having visited the site or seen high-quality images, he is doubtful the prints were made by sea turtles. “The surface marks do not show the spacing, rhythm or anatomy expected from sea turtle flipper strokes,” he says. “I am of the opinion they are not of biological origin, but are instead abiotic structures.”

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