Bioevent
A bioevent or bio-event (a shortening of 'biotic event' or 'biological event') is an event recognised in a sequence of sedimentary rocks, where there is a significant change in the biota as recorded by assemblages of fossils over a relatively short period of time. It has been defined as "short-term (hours or days to kyrs) locally, regionally, or interregionally pervasive changes in the ecological, biogeographical, and/or evolutionary character of biotas that are isochronous or nearly so throughout their range".