The lower Maastrichtian chalk of the Isle of Rügen was deposited in a pelagic setting in the aphotic zone. Its rich fossil content has attracted research attention for centuries, whereas its ichnological characteristics remain poorly understood, even though horizons with intense bioturbation and occurrences of trace fossils in flint are common. The enhanced colour contrast of smooth chalk faces reveals repeated phases of benthic colonisation; larger burrows are commonly subject to silicification, while flint nodules also can preserve burrows in chalk. A total of 37 ichnogenera, including 47 ichnospecies of bioturbation and bioerosion trace fossils have been recognised; these are here briefly described, in addition to indeterminate material. Many ichnotaxa are recorded for the first time from the Rügen chalk. Bioerosion is restricted mainly to local hardgrounds in the form of biogenic components (such as shells and belemnite guards).

The present study reports polychaetes that bore into limestone rocks along the east coast of the Aegean Sea (eastern Mediterranean). Rock materials were collected at two depth intervals (0–5 and 5–10 m) at 15 stations in four localities of Ildırı Bay. A total of 276 specimens belonging to 12 species and four families (Eunicidae, Spionidae, Cirratulidae and Sabellidae) were recorded. Specimens belonging to Dodecaceria and Pseudopotamilla were identified at the genus level, because they differ from described species, were few in number or were in poor condition. Dipolydora giardia is a new species to the marine fauna of Turkey. The most dominant and frequent family in the area was Eunicidae, followed by Spionidae. Lysidice ninetta and L. margaritacea comprised 59% of the total number of individuals. The number of species and individuals, and the diversity index did not change with regard to depth or locality. Two species assemblages were found in the area, mainly formed by Dipolydora and Lysidice species. The Lessepsian species, Palola valida, which is a new record for the Aegean Sea, occurred abundantly at the study sites, posing a risk of damage to limestone rocks in the Mediterranean Sea. The morphological features of the species identified at the generic level and the burrow structure of these species are presented. The burrow shapes of Palola siciliensis and P. valida were described for the first time in the present study; they constructed complicated galleries, including more than four entrances.

This study describes bioerosion traces ascribed to either predation or endo- and epibiont activity in twenty assemblages from the Mediterranean region and Paratethys, spanning in age from Eocene to Recent. Statistical analysis of the distribution of bioerosion traces among genera and assemblages revealed that there is higher drilling predation intensity on smaller species. Larger species seem to be primarily affected by non-drilling predators. Greatest variety in types of bioerosion could be related to species’ ecology and body size. Both major categories of bioerosion (etchings and traces of predatory activity) vary considerably among samples. Different genera show significant differences in the frequency of different bioerosion types. Shell size seems a major factor contributing to these differences.