Hiker's Find Leads to Trove of Fossils Predating Dinosaurs

Claudia Steffensen was hiking in the Italian Alps last summer when she stepped on a rock that caught her eye. "It seemed more like a slab of cement" with "these strange circular designs with wavy lines," Steffensen tells the Guardian. "I took a closer look and realized they were footprints." Since Steffensen's discovery, scientists have found hundreds of other plant and animal fossils at altitudes of nearly 10,000 feet in northern Italy's Valtellina Orobie Mountains Park, close to the Swiss border. Experts say the footprints of reptiles, amphibians, and insects are traces of a prehistoric ecosystem dating back 280 million years to the Permian period, the age immediately preceding the arrival of the dinosaurs.

"Dinosaurs did not yet exist, but the authors of the largest footprints must still have been of a considerable size," up to 10 feet long, says Cristiano Dal Sasso, a paleontologist at the Natural History Museum in Milan who helped identify the footprints Steffensen spotted. Lorenzo Marchetti, an expert in trace fossils at the Museum of Natural History in Berlin, says the fossils show "impressive details," including "the imprints of fingernails and the belly skin of some animals." There are also "imprints of very thin fingers, trails of long sinuous tails, ripples of waves on the shores of ancient lakes and even drops of rain fallen on the mud," according to a report from the University of Pavia.

Doriano Codega, president of the nature park, calls it "a very important paleontological discovery" in part because the fossils, preserved in slabs of sandstone that once formed the edges of lakes and rivers that periodically dried up, were found at high altitudes, where there's less sediment and higher erosion. "Rock detachments" may have unearthed some of the fossils, which predate the largest mass extinction in history, the Permian-Triassic extinction dated to around 252 million years ago, Codega notes. Most were revealed through the melting of ice and snow through climate change. Some fossils have been moved to Milan's Natural History Museum for display, per Interesting Engineering. Research in the park continues. (More discoveries stories.)