Increase of shell-crushing predation recorded in fossil shell fragmentation

Abstract

Abstract The Mesozoic marine revolution focuses on increased predation by durophagous (shell-crushing) predators and the concomitant evolution of prey organisms that occurred in the Mesozoic. Evidence of this predator/prey revolution is found in the appearance and increase of new types of predators that can crush hard shells of prey organisms, and is also found in the morphological changes of prey organisms, such as the appearance of a protective shell morphology of gastropods. We present new data based on the occurrence of shell fragments that indicate a slower increase in durophagous predation than has been considered previously. The results of an experiment on shell abrasion, in which shells were tumbled in barrels with sediments, indicate that incomplete bivalves and gastropods with angular margins from shallow-marine deposits can be considered as good evidence of durophagous predation. Such angular shell fragments are virtually absent from Japanese Mesozoic shell beds, whereas they are occasionally o...