Life’s first flourish
FORMED BY THE gentle lapping of waves in warm and shallow seas, the undulating ridges of sand beneath my feet look as if they were sculpted this morning. As expected in a coastal marine environment, they are decorated with impressions of diverse and abundant life. There are marks where stems attached to the sea floor and fronds were dragged by the tide; indeterminate dimples and ripples; footprints and scratches left by foragers in the silt.
But this large slab of coastal ecosystem is no longer on a sea floor and wasn’t forged by recent wave action. It is on a wind-blustered hill at Nilpena Station on the western edge of the Flinders Ranges, and I’m standing on a fossilised ocean bottom formed 550 million years ago, when this part of South Australia was the continent’s eastern seaboard.
The soft-bodied animals preserved as tiny moulds and casts are like nothing familiar today. The perhaps 50 species recorded here are some of Earth’s earliest examples of animal life, and are of great interest to NASA as it prepares to recognise unfamiliar alien life on far-off worlds.
“The fossil beds of Nilpena rank among the world’s top two or three archives of early animal life,” says Dr Timothy Lyons, of the Alternative Earths teams at the NASA Astrobiology Institute at Mountain View, California. Not only do Nilpena’s strange fossils hint at the variety of forms life can take, they’ve illuminated many milestones of evolution.
Identified by acronyms such as ARB (Alice’s Restaurant Bed) or BRW (Biggest Rock in the World), slabs of prehistoric sea floor excavated on this arid, dusty hillside have become the life’s work of Professor Mary Droser, a University of California, Riverside, palaeobiologist, who
