2025/03/10 by Cui Luo, Maoyan Zhu, Zhu Maoyan
Earth and Planetary Sciences · Environmental Science · #Paleontology and Stratigraphy of Fossils #Geological and Geophysical Studies #Methane Hydrates and Related Phenomena
paper · doi:10.1130/g52956.1
Abstract The Phanerozoic-type biosphere was set up during the Cambrian explosion when the ecosystem dominated by microbes and Ediacara-type biota shifted to accommodate burgeoning animal communities. However, our knowledge about the processes and mechanisms of this biosphere revolution is still fragmentary, partly due to the incomplete paleontological data constrained by the availability of taphonomic windows. This study underlines the potential of chert Lagerstätten to supplement our understanding of the biospheric changes across the Ediacaran–Cambrian boundary. Cherts from eight outcrops in different sedimentary facies of the Yangtze craton demonstrate contrasting fossil assemblages between the topmost Ediacaran and the basal Cambrian intervals. The Ediacaran assemblage is uniform and dominated by enigmatic string- and strap-like fossils, while the Terreneuvian assemblage encompasses a large variety of carbonaceous microfossils and mineralized skeletons, reflecting a novel complex ecosystem. Both assemblages have members that are distributed from proximal to distal facies. Notably, various peculiar filmy fossils of possible metazoan affinities are common in the Cambrian assemblage but appear to be absent in the Ediacaran and older cherts, implying abrupt innovation of complex multicellular eukaryotes in the earliest Cambrian. Although the innovation has been observed in continuously outcropping chert successions across the Ediacaran–Cambrian boundary, further investigation is required to test whether the contrasting fossil assemblages reflect taphonomic bias or an inconspicuous hiatus.