Research project P4S/251/AMNOXYKO (Research action P4S)
Fossil-rich sedimentary sequences record past environmental crises, preserving evidence of ancient ecosystem dynamics. The Kellwasser Crises 372 million years ago at the end of the Frasnian (Upper Devonian), caused coral reef collapse, widespread hypoxia to euxinia, and a 1st order mass extinction—one of the Big Five— and has the highly diverse iconic Gephuroceratin ammonoid cephalopods, such as Manticoceras, among its famous victims. However, the onset of Kellwasser Crises and the ecological transformations it drove in the final stages of the Frasnian remain poorly understood. How did declining oxygen levels shape marine communities struggling for survival at the very end of the Frasnian?
Over the past 12 years, as part of the monitoring of high-potential fossil localities, RBINS staff collaborating with citizen scientists discovered an exceptionally expanded fossil-rich section in the Lompret Quarry (Chimay, Belgium), dating to the Kellwasser onset within the (historical) type area of the Frasnian Stage. This site surpasses many of the renowned Kellwasser sections in the world in stratigraphic thickness, fossil abundance, and preservation quality. Key finds include exquisitely preserved ammonoids, from embryonic shells up to giant >40 cm diameter specimens, a set of mass-mortality beds, a new giant predator fish Dunkleosteus, and Belgium’s largest Kellwasser invertebrate macrofossil collection.
The AMNOXYKO project will leverage this unique addition to the federal collection to investigate ammonoid (Gephuroceratina, Tornoceratina) and other cephalopods (Bactritida, Orthocerida, Oncocerida) diversity resolving long-standing issues on their diversity in the Frasnian type area, using both conventional and novel techniques like micro-CT, and making digital models of all encountered species openly accessible on the RBINS Virtual Collections Platform. It will also examine, at unprecedented resolution, the abundance, distribution, composition, and interrelationships between nektonic (Cephalopoda) and (opportunistic) benthic macroinvertebrates with high preservation potential (bivalves, gastropods, brachiopods), assessing how the Frasnian ecosystem adapted to declining oxygen levels amid an impending mass extinction.
By integrating macroinvertebrate data from normal and mass-mortality beds with sedimentological and geochemical deoxygenation proxies (microfacies in thin sections, clay mineralogy, AI-driven pyrite framboid analyses, δ13C and redox sensitive metals), this research will develop a novel calibrated high-resolution faunal deoxygenation proxy, complementing traditional proxies but pivotal to an unprecedented detailed understanding of the Kellwasser crises. Additionally, it will yield new insights into ammonoid paleobiology and environmental partitioning, potentially revealing life-cycle-based ecological differentiation. δ13C chemostratigraphy will support ammonoid and conodont biostratigraphy to place findings from Lompret Quarry within the most refined global temporal context possible.
By combining multiple lines of evidence and uniting expertise across federal, regional, and international levels, this study will establish Lompret Quarry as a new Devonian deoxygenation reference section, further developing Belgian geoheritage and its value for society. Providing a detailed case study of ecosystem responses to extreme stress, these findings will contribute to broader discussions on oceanic anoxia’s long-term impacts, drawing parallels with modern deoxygenation trends. With the rapid spread of hypoxic death zones and coral reef collapse as two important tipping points in present-day climate change, this work—while primarily a Belgian heritage project built on the federal collection and in close collaboration with citizen-scientists—will enhance our understanding of past extinctions and offer critical insights into marine ecosystem resilience under present and future climate scenarios using novel methodologies.
