An entire ecosystem dating back 280 million years has been discovered in Valtellina

Environment · Maurizio Bongioanni · 2024-11-14

A hiker accidentally discovered a fossil site dating from the Permian period, in the Parco delle Orobie valtellinesi.

An entire ecosystem fossilised on fine-grained sandstone slabs, which have preserved unimaginable details, lay hidden among the Alpine peaks in Valtellina for 280 million years.
Now the reduction of snow and glacier cover caused by climate change is bringing it back to light, revealing incredible traces of prehistoric life and nature.

In the heart of the Parco delle Orobie della Valtellina, in the province of Sondrio, an extraordinary discovery has emerged: an entire fossilised ecosystem, brought back to light by the melting of a glacier caused by climate change. The fossils revealed bear the impressions of slender toes, the trails of long sinuous tails, ripple marks on the shores of ancient lakes, and even raindrops that fell on mud before it became stone embedded in the walls of the Orobie Valtellinesi Alps — all dating back 280 million years, to the Permian period.

Detail of the fossiliferous stratifications. During the Alpine orogeny (that is, the formation of our mountains) these ancient lake beds were raised and rotated, becoming almost vertical rock faces © Elio Della Ferrera

Particularly fascinating are the raindrops imprinted in the mud, which during the dry season hardened sufficiently to avoid being liquefied again when, months later, it was covered by further mud. The level of detail is so high that it allows the angle at which the rain fell to the ground to be calculated, millions and millions of years ago. Photo by Elio della Ferrera, © Soprintendenza Archeologia, Belle Arti e Paesaggio delle province di Como, Lecco, Monza-Brianza, Pavia, Sondrio e Varese

An exceptional fossil: this is the skin impression of a reptile, made more than 280 million years ago when the animal rested its belly for a few moments on water-softened clay ground. Photo by Elio Della Ferrera © Soprintendenza Archeologia, Belle Arti e Paesaggio delle province di Como, Lecco, Monza-Brianza, Pavia, Sondrio e Varese.

A remarkable branched plant frond, found by Elio Della Ferrera months ago, is now covered by a recent landslide but could potentially be recovered as its GPS position has been recorded. Photo by Elio Della Ferrera, © Soprintendenza Archeologia, Belle Arti e Paesaggio delle province di Como, Lecco, Monza-Brianza, Pavia, Sondrio e Varese.

Marco Cattaneo examines boulder 0: the first boulder with footprints found by Claudia Steffensen. The first trace that led to the discovery of the Val d'Ambria deposit © Elio Della Ferrera

Valtellina's fossils are kept at the museum

The site was discovered by chance by hiker Claudia Steffensen and documented by nature photographer Elio Della Ferrera. It was subsequently the subject of in-depth study by a team of experts, including palaeontologist Cristiano Dal Sasso from the Milan natural history museum, geologist Ausonio Ronchi from the University of Pavia, and ichnologist Lorenzo Marchetti from the Berlin natural history museum. In a spectacular recovery operation, the first finds were transported down to the valley with the aid of a helicopter and were presented to the public at the Milan natural history museum.

The experts identified the footprints of at least five animal species. The fossilised "trackways" — sequences of footprints left by animals walking on still-muddy sediments — offer a unique window onto an ecosystem from an era in which dinosaurs did not yet exist. The size of the footprints indicates animals between 2 and 3 metres in length. "The quality of preservation is such that it shows even the details of the toe pads and belly skin," notes Marchetti, highlighting the importance of the site for the study of Palaeozoic era biodiversity. In addition to animal traces, plant fossils are also present in Val d'Ambria — though rarer — including fronds, stem fragments and seeds. Equally interesting sedimentary structures include desiccation cracks, ripple marks from wave action or current, and raindrop impressions, all of which are providing researchers with a wealth of data for a detailed palaeoenvironmental and palaeoclimatic reconstruction.

The geological conditions in which these sediments formed explain the extraordinary preservation of the traces. "The footprints were preserved thanks to the seasonal cyclicity that led to the summer desiccation of the muddy surfaces, followed by new layers of protective clay," explains geologist Ronchi.

fossili-valtellina6 — The research team at work © Elio Della Ferrera

The past offers us a precious lesson

One might wonder what the point of all this is. The research team is unanimous in its answer: "These discoveries are not of scientific interest alone. In terms of the extent and complexity of the stratifications, this new site represents an important addition to the fossil footprint deposits of the same era that have made the Italian southern Alpine sector a place of worldwide significance. But these fossils also tell of a geological period in the distant past that, as today, was marked by global warming, with the greenhouse effect driven by massive volcanic eruptions, the melting of the polar ice caps and the expansion of increasingly arid seasonal tropical environments. This favoured reptiles over amphibians and led to the extinction of many species. The past offers us a precious lesson about what we risk causing on our planet today."

Indeed, the discovery in Valtellina, as well as enriching our knowledge of life in the Permian period, represents a curious paradox: it is precisely the melting of glaciers, caused by climate change accelerating in the modern era, that is now giving palaeontologists the opportunity to study these incredible finds. As geological eras meet in a strange twist of fate, it is as though the past is unveiling itself to warn us not to suffer the same fate as the dinosaurs.