The mystery of why rocky cliffs near Ancona, Italy, are covered in thousands of moon-shaped marks may have finally been solved.
Curious rock climbers stumbled on strange grooves while hiking along a rock face on Monte Cònero overlooking the Adriatic Sea in 2019.
But scientists think they finally know what caused all these bizarre marks – a stampede of sea turtles 80 million years ago.
A study published in the journal Cretaceous Research said the limestone slab was once an ancient seafloor pushed upwards by an earthquake.
Researchers from the Coldigioco Geological Observatory had a hunch that the imperfections, which appeared in pairs, were likely made by fins.
Then it was trial by elimination – fish are just too squishy and light to leave the marks, so reptiles made the most sense.
Two candidates – the giant mosasaurs and plesiosaurs, which had a mouth full of needle-sharp teeth – were both loners, so probably not them either.
That left just one reptile that roamed the seas of the Late Cretaceous period, the lowly sea turtle.
The team said the fossilised seafloor-turned-cliffside in Cònero Regional Park was once hundreds-of-meters deep.
Then one day, an earthquake sparked a mass evacuation of a sea turtle colony, paddling towards the open ocean, the paper suggested.
Amid the shaking, an underwater avalanche of mud smothered the seafloor, preserving the turtles’ footsteps (fin-steps?).
Suck underwater tracks are uncommon, given that currents can easily sweep evidence away.
The paper says that their findings aren’t conclusive and ichnologists – experts who study fossil tracks – need to give it a look.
But Peter Falkingham, a professor of palaeobiology at Liverpool John Moores University who wasn’t involved in the paper, isn’t so convinced.
‘I don’t see much evidence in the paper that these are actually tracks,’ he tells Metro.
‘The fact they are so uniform and extensive over the surface makes them look more like truncated ripple marks to me.’
Professor Falkingham says he’s never seen flipper impressions like those on the cliffs before.
So if it wasn’t a fish or a reptile, there’s only one thing left.
‘I don’t think there’s anywhere near enough evidence to back up the claim of “probably represent a stampede of panicking sea turtles that were mobilised en masse by an earthquake,”‘ he stresses.
‘I think it’s more likely this is a natural texture of the sediment caused by the movement of water.’
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