FrasnianFamennian

The FrasnianFamennian event refers to a major mass extinction that marks the boundary between the Frasnian and Famennian stages of the Late Devonian. Occurring roughly between 372 and 359 million years ago, it is commonly cited as one of the most significant extinction events in Earth’s history, often grouped among the “Big Five” Phanerozoic mass extinctions. The crisis is associated with two prolonged phases known collectively as the Kellwasser events, which affected global faunas and floras.

The extinction had a substantial impact on marine life, with widespread losses among reef builders and many pelagic and benthic groups. Rugose and tabulate corals declined sharply, as did various brachiopods, trilobites, and armored fish such as placoderms. Conodonts and ammonoids also suffered heavy losses, and reef ecosystems on continental shelves collapsed in many regions. Terrestrial life was less rapidly affected in comparison, but the broader evolutionary pace of the Devonian fauna was altered, contributing to a shift toward vertebrate and terrestrial ecosystem diversification in the subsequent Mississippian.

Causes of the FrasnianFamennian extinction are widely debated and likely involve multiple interacting factors. Proposed mechanisms include episodes of global oceanic anoxia, climate fluctuations, changes in sea level, and nutrient loading that fostered harmful algal blooms. Volcanic activity or tectonic processes may have contributed to environmental stress, disrupting calcification and food webs.

The FrasnianFamennian boundary set the stage for subsequent Devonian to Carboniferous faunal transitions, with surviving lineages radiating in the Early Carboniferous. It remains a focal point for studies of stratigraphy, paleoceanography, and mass extinction dynamics.