Scientists have found a treasure trove of tiny fossils in the rocks of Greenland. The microscopic organisms date to more than half a billion years ago, offering new insights into the Cambrian Explosion, a dramatic increase in the planet’s biodiversity that began 541 million years ago.
During this period, Earth’s shallow seas teemed with life, and the first modern ecosystems formed — animal and plant life as we recognize it today was born.
The details of this dramatic evolution have been revealed by world-famous excavation sites like the Burgess Shale, a bed of shale exposed in the Canadian Rockies. Similarly aged strata has also been found in Greenland, but most of the fossils at Sirius Passet belong to larger creatures and hard-bodied organisms.
Heat generated by tectonic activity over the last 500 million years has melted Greenland’s rocks several times, destroying much of the fossilized evidence of soft bodied organisms from the Cambrian Period.
But a team from Uppsala University in Sweden discovered an outcropping of rocks that escaped much of the heating and subsequent damage. There, just south of Sirius Passet, an acid extraction procedure used to dissolve layers of mudrock revealed a multitude of tiny fossils representing soft-bodied Cambrian life.
The rocks are filled with tiny fossils, most of them smaller than a millimeter in length and requiring a microscope for examination. Among other fossils, researchers discovered the preserved hook-like teeth of priapulid worms, which the predators used to burrow into the mud in search of prey.
Scientists found fragments of the oldest known pterobranch hemichordate, a rare group of tube-dwelling filter feeders. The rocks also revealed fossilized defensive spines belonging to a variety of arthropods. Researchers described their impressive fossil haul in a new paper published this week in the journal Geology.
“The sheer abundance of these miniature animal fossils means that we have only begun to scratch the surface of this overlooked resource, but it is already clear that this discovery will help to reshape our view of the non-shelly animals that crawled and swam among the early Cambrian seas more than half a billion years ago,” Uppsala researcher Sebastian Willman said in a news release.