The Late Devonian mass extinction event represents a profound biotic crisis that occurred during the Devonian period of Earth's history. This extinction event significantly altered global ecosystems, marking a major turnover in the diversity of life. While the exact combination of triggers remains a subject of scientific inquiry, leading hypotheses point to a combination of severe environmental stressors, including widespread oceanic anoxia (the depletion of dissolved oxygen), potential changes in global sea levels, and sustained shifts in climate patterns. The impact profoundly affected marine and terrestrial life, drastically reducing the populations of various groups, including trilobites and placoderms, and leading to major adaptive radiation among surviving groups of organisms.