Article: Durophagous predation on Middle Jurassic molluscs, as evidenced from shell fragmentation
Durophagous (shell-crushing) predation is known from the beginning of the Phanerozoic, but it has been suggested that modern intensity was not reached until the Late Cretaceous and Early Cenozoic, when specialized marine durophagous taxa increased in diversity. In this paper, evidence of durophagous predation on Middle Jurassic communities of molluscan prey is presented on the basis of distinct accumulations of fossil remains in the Polish Jura (south-central Poland) that contain characteristic, angular shell fragments with sharp, non-abraded margins. The diverse fossil content of the accumulations studied, consisting of either benthic or nektic/nekto-benthic taxa, indicates that the potential predatory taxon was an opportunistic generalist, most probably fish. On the basis of taphonomic observations, the faunal accumulations are interpreted to represent regurgitated remains (pellets). The common occurrence of such accumulations in the Middle Jurassic clays of the Polish Jura indicates that durophagous predation has been intense since the mid-Mesozoic, at least locally.