Paleontologists have unearthed a treasure trove of fossils from 512 million years ago including 90 species previously unknown to science. The discovery comprises 153 different species from 16 major animal groups including sponges, arthropods and bizarre segmented apex predators known as radiodonts that make up a complex food web, dating back right after a mass extinction called the Sinsk event which was driven by a deadly drop in ocean oxygen. The Sinsk event ended the sudden increase of complex life that began 540 million years ago in what geologists call the Cambrian explosion, often dubbed the Biological Big Bang when nearly all major animal groups began appearing in the fossil record. Most knowledge about Cambrian life comes from fossil deposits that formed under special conditions allowing exceptional preservation even recording soft tissue parts, with the premier example being the Burgess Shale, a 508 million year old rock unit from the Canadian Rockies.
The Burgess Shale came 5.5 million years after the Sinsk event while other high quality fossil deposits came before the mass extinction, meaning the exact impact of the event which had extinction rates of 41 to 49 percent has been unclear until now. Comparison between the Huayuan biota and 45 other Cambrian fossil deposits from around the globe revealed strong links to the younger Burgess Shale deposits, suggesting Cambrian life was dispersed long distances across oceans by currents and sea level changes. Paleontologists report that deep water environments were less affected by the Sinsk event than shallow water counterparts and perhaps served as refuges for life or sites of evolutionary innovation, finally filling in the missing chapter of what happened after nearly half of all species on Earth vanished.
Source: https://www.newsweek.com/fossils-paleontology-cambrian-explosion-sinsk-event-lagerstatte-11430812
