Italian climbers find trace fossils of sea turtles that were fleeing an earthquake 80 million years ago

The imposing heights of the Umbria-Marche Apennines in central Italy offer some of the best weekend destinations for adventurous souls looking to climb challenging walls. But a typical Sunday adventure for a bunch of local rock climbers has led to what could be considered among the most astounding discoveries from prehistory ever made, a place where an ordinary climbing experience became an amazing find. The adventure began with just another climb along the face of a high wall overlooking the Adriatic Sea and ended with the unexpected finding of a fossilised underwater stampede.

As they made their way along the rock face, the climbers came across something quite remarkable: a set of unusually deep and even, parallel grooves cut into the rock. They soon deduced that, because of their highly structured nature, these marks could not have been caused by recent erosion, and turned to the geological authorities in the area for help. As the geologists climbed the face of the cliffs to inspect the grooves, they took advantage of drone imaging technology and samples to reconstruct an incredible tale of survival. The grooves themselves turned out to have been created by ancient sea turtles fleeing an underwater earthquake.

A deep-sea catastrophe in stone

To grasp how a catastrophic ancient event ended up leaving traces on the side of an Italian mountain range, geologists needed to take a closer look at the complicated geology of the area. Long, long ago, what is now an Italian mountain range was a seabed lying deep beneath the surface of the ocean. However, over millions of years, geological processes raised this seabed to the heights of a mountain range that rock climbers explore today.

An extensive scientific paper published in the reputable science journal Cretaceous Research looked closely at the geological composition of the layers of rock at the site. What the team of researchers found was that the unusual marks were inscribed within the layers of the Scaglia Rossa Formation, a special limestone formation known for its bright pink colouration.

According to the geological data obtained in the aforementioned study, an extremely powerful earthquake wave occurred on Earth at the end of the Late Cretaceous epoch, generating powerful shockwaves on the ocean bottom. Due to the occurrence of such an earthquake, a whole group of sea reptiles found themselves in a state of panic. Desiring to move away from the trembling Earth crust, a whole crowd of sea turtles rushed to the seabed and, using their strong front limbs, started sliding from there, thus creating a confused network of traces in the process.

These remarkable grooves, preserved for eighty million years within the Scaglia Rossa Formation, were created as the turtles slid across the seabed, later buried by a massive sediment shift. Image Credits: Reptile footprints on a pelagic seafloor as a vestige of a synsedimentary seismic event in the lower Campanian Scaglia Rossa basin of the Umbria-Marche Apennines (Italy) study Fig 4

The perfect geological storm

Under ordinary conditions in the ocean depths, traces left by marine animals disappear quite quickly, as ocean waves and living creatures that drill holes destroy all traces of life within a few hours or days. To have such footprints preserved for eighty million years required ideal geological circumstances.

The secret to this incredible preservation lies in the immediate aftermath of the ancient earthquake. Another crucial piece of scientific literature from the area, a study exploring earthquake-induced turbidites published in the journal Terra Nova, outlines how sudden tectonic shocks in the region routinely destabilised underwater slopes and generated massive sediment shifts.

Not long after the frightened sea turtles swam across the bottom of the sea, the earthquake that scared them caused an immediate mudslide in the water. The avalanche-like mud flowed down the marine slope and deposited thick sediments that completely covered the newly made prints. In doing so, the mudflow preserved the tracks from any damage that the currents and oxygen from the ocean could cause to them. Over many millions of years, the sediments fossilised due to enormous pressure and became a time capsule preserving these last minutes of the sea turtles.