A group of Neanderthal children scampered around the Normandy coast in France 80,000 years ago. Their footprints quickly became covered by windblown sand, preserved as ghostly signs of their passage.

The tracks were eventually discovered by archaeologists working at a site called Le Rozel on the country’s northwestern shore. Carefully brushing away layers of sand, the scientists found 257 footprints between 2012 and 2017. The team described the collection in a paper published Monday in the Proceedings of the National Academy of Sciences.

Evidence from Neanderthal fossils and artifacts discovered across Europe and Asia has slowly painted a picture of the culturally and socially complex lives of our closest extinct human relatives. Contrary to long-held beliefs, Neanderthals were not backward cave men. Scientists have found artifacts that suggest they crafted stone tools, made cave art and carried out various rituals, such as burying their dead.

But a few fossils and isolated artifacts don’t tell the whole story.

“It is really difficult to study the composition and size of Neanderthal groups from skeletal remains and stone tools,” said Jeremy Duveau, a graduate student in paleoanthropology at the French National Museum of Natural History, who led the new study.