Drilling predation on Early Jurassic bivalves and behavioral patterns of the presumed gastropod predator — evidence from Pliensbachian soft bottom deposits of northern Germany

Drilling predation is a common reason for mortality of benthic molluscs but did not become common until the late Mesozoic. The scarcity of drill holes in the early Mesozoic fossil record limits our understanding of the evolution of drilling behavior and its role on shaping early Mesozoic marine communities. Here, we use drilling traces on several bivalve taxa from the Lower Jurassic (Pliensbachian) marine soft bottom deposits in northern Germany to explore behavioral patterns of the predator (e.g., site selectivity, change in site-selective behaviour with age). Although none of the known drilling gastropod groups existed in the Pliensbachian, including the studied localities, the drill hole morphology suggests that the predator was probably a gastropod. The ecology and identity of the target prey change from a diverse array of epifaunal to infaunal taxa in older deposits to focus on a single large deep infaunal taxon, Gresslya intermedia, in younger deposits, suggesting a potential tren..., Size measurements were made with a digital caliper.,