Global correlation of small shelly fossils from North Greenland and their importance for early Cambrian ecosystem change

During the Cambrian explosion, animals underwent profound ecological and evolutionary configuration. Small shelly fossils (SSFs), micrometre- to millimetre-scale skeletal elements representing multiple animal phyla, are particularly valuable for early Cambrian biostratigraphy and intercontinental correlation because of their widespread distribution. SSFs from North Greenland provide a high-resolution record of biotic and environmental change along the eastern margin of Laurentia. Here, we document a SSF assemblage that includes molluscs, hyoliths, brachiopods, ecdysozoans, echinoderms, and several problematic taxa from the Aftenstjernesø Formation in North Greenland. This integrated dataset enables detailed correlation with other Cambrian Series 2, Stage 4 successions on several palaeocontinents, including Gondwana, Siberia, and peri-Gondwana, based on shared taxa. During this period, many regions record a major faunal collapse associated with the first widely recognized Phanerozoic extinction event, the so-called Sinsk event, which has been linked to marine anoxia, decrease of diversity, and body-size reduction. In contrast, the Laurentian margin records pronounced taxonomic turnover dominated by faunal replacement rather than a net loss of diversity. This difference underscores the importance of palaeogeography and local geodynamic conditions in modulating how early Cambrian environmental crises were expressed biologically, and it demonstrates the utility of SSFs for reconstructing the biotic response to early Cambrian environmental crises.