ABSTRACT. An exceptionally well-preserved fauna from a new exposure in the Peterborough Member (Oxford Clay Formation) of southern England, equivalent to the famous and now inaccessible Lagersta Ètte at Christian Malford, Wiltshire, is described. It comes from a single bed and includes coleoid cephalopods with phosphatized soft tissues, and fully articulated ®sh. The level is unusual in that it lacks permanent benthos and is dominated by`rain-out' from the upper water column. It was deposited on a sea¯oor that experienced prolonged periods of anoxia and which was overlain by a water column that was at least intermittently strati®ed. It is postulated that the coleoids formed large shoals that were killed en masse, together with other elements of the associated fauna, in one or more catastrophic mass mortality events that affected a signi®cant area of the Peterborough Member sea. During the event(s), many of the coleoids preyed upon moribund ®sh and other coleoids, sometimes of the same species, before becoming overcome themselves. Crucially for the phosphatization of their soft tissues, the substrate surface was`soupy' and allowed them to sink to a zone of rapid diagenesis where levels of dissolved phosphorus were greatly augmented by the large number of associated decaying carcasses.