Microbioerosion

Microbioerosion ichnocoenoses are produced by euendolithic microorganisms including bacteria, cyanobacteria, chlorophytes, rhodophytes, and fungi, which either find shelter from grazers and physical disturbances or seek nutrition within the mineralized substrate they dissolve. Most microborings perfectly match the outline of the organisms producing them and thus can be assigned to their living tracemaker with a fair degree of confidence. A favorable concert of evolutionary longevity and environmental dependency make them superb paleoenvironmental indicators for all Phanerozoic strata that contain well-preserved fossil skeletal material. The present chapter provides the sedimentologist, ichnologist, or paleoecologist with a review of the methodological toolkit at hand to study these microscopic structures (petrographic thin sections, SEM of epoxy resin casts, and microcomputed tomography), a comprehensive overview of microboring biota and the trace fossils they produce, and a review and outlook of their applicability for paleoenvironmental studies with respect to paleobathymetry, paleothermometry, paleosalinity, and paleotrophodynamics.