Bioerosive structures in orbitolinid foraminifera:

Abstract. Lower Cretaceous orbitolinid assemblages from Central Iran yield various bioerosional structures. The omnipresent traces of different boring taxa and groups (e.g., sponges, calcimicrobes, incertae sedis) represent a characteristic feature of the investigated thin-section material. The assemblage can be attributed to the Entobia ichnofacies dominated by borings assigned to the activity of sponges. The boring galleries are often concentrated in a plane parallel to the test surface, along the boundary of the marginal and the central zone of the orbitolinid tests. The borings are observed in foraminiferan-dasycladalean wackestones to poorly washed-out packstones, which can be referred to a subtidal palaeoenvironment