Discovery of agglutinated benthic foraminifera in Devonian black shales and their relevance for the redox state of ancient seas

Agglutinated foraminifera are benthic organisms that occur in marginal marine to bathyal environments. Though some taxa can live in oxygen deficient environments, they require at least some oxygen in order to persist at the seafloor. The discovery that they occur widely in Late Devonian black shales has a bearing on the boundary conditions required for episodes of extensive carbon sequestration in marine sediments and their connection to atmospheric composition and global climate. Devonian black shales of the eastern US have been studied extensively to determine the fundamental controls on carbon burial, and a range of mechanisms has been proposed. Finding agglutinated benthic foraminifera in these black shales refocuses the debate about their origin and points to limitations of earlier models.