Charles Darwin had been troubled by a gap. The fossil record seemed to begin suddenly, with the hard-shelled creatures of the Cambrian, and nothing came before. The Ediacara biota are what came before - the missing pages. These were not animals as we picture them. Some resembled quilted mattresses, others ribbed fronds anchored to the mud, others soft discs the size of a dinner plate. Among Sprigg's finds was the first evidence of an animal with a distinct head end, a segmented creature later named Spriggina in his honour. They drifted and grazed in a world without predators, without teeth, without the violence that the Cambrian would soon unleash. For a few million years, before complex life learned to eat itself, the sea was strangely peaceful.

It is rare for science to add a wholly new period to the geological calendar. In 2004, the International Union of Geological Sciences did exactly that, ratifying the Ediacaran Period - the first new period defined in roughly 120 years, and the first ever anchored in the southern hemisphere. Its formal starting point, a marker geologists call the "golden spike," was driven into a creek bed at Enorama Creek in Brachina Gorge, a short drive from here. Of the dozens of such markers worldwide, this is the only one below the equator. The name itself comes from the Ediacara Hills, and its origin in local Aboriginal language is debated - some suggest a term linked to water, others a phrase meaning hard, stony ground, a fitting description of the dolomite flats at the area's heart.

What makes Nilpena extraordinary is not single fossils but entire fossilised seafloors, lifted and turned over so that an ancient community can be studied as it lived. American palaeontologist Mary Droser has travelled here from California for more than two decades, working with researchers from the South Australian Museum to excavate these beds bed by bed. By flipping massive slabs of sandstone, they read whole ecosystems - who lived next to whom, how the creatures fed, how they moved. It is less like digging up bones and more like turning the pages of a 550-million-year-old photograph album, each layer a frozen moment from a vanished world.

For generations this was Nilpena Station, grazing land worked by the Fargher family, who came to understand the treasure beneath their paddocks and quietly protected it. In 2019 the South Australian government bought a large portion of the station, enlarging the protected area roughly tenfold. The park was proclaimed in 2021 and opened to visitors in April 2023. Ross and Jane Fargher stayed on as caretakers of the fossil beds. The whole landscape lies on the traditional country of the Adnyamathanha people, whose deep connection to this land stretches back tens of thousands of years - a continuity of human presence almost as humbling, in its way, as the deep time written in the rock. The site anchors a bid for UNESCO World Heritage listing for the Flinders Ranges.