Did the Puchezh-Katunki Impact Trigger an Extinction?

Abstract. The 80 km Puchezh-Katunki impact crater is the only one of the six largest known Phanerozoic craters which has not been previously considered as a factor in a biotic extinction event. The age of impact is currently regarded as Ba-jocian (Middle Jurassic), on the basis of palynostratigraphy of crater lake sedi-ments, but there is no significant extinction in the Bajocian. Earlier K-Ar age de-terminations of impactites compared with a current Jurassic time scale permit that either the end-Triassic or the Early Jurassic (Pliensbachian-Toarcian) extinction was coeval with the Puchezh-Katunki crater. The stratigraphical and paleontologi-cal record contains clues that suggest that an impact may have occurred at these horizons. The age of the Puchezh-Katunki crater needs reevaluation through 40Ar/39Ar dating of impact rocks and/or revision of the palynology of the oldest crater fill. A definitive age determination will help constrain the impact-kill curve.