Angiosperm tree leaf as a bryozoan substrate: a case study from the Cretaceous and its taphonomic consequences

Apart from seagrasses, angiosperm leaves are rare substrates for marine bryozoans today and in the geological past. Here we describe two leaflets of a compound angiosperm tree leaf overgrown by bryozoan colonies from the Coniacian Wartowice beds in the upper part of the Rakowice Wielkie Formation in Lower Silesia. The bryozoans are preserved as moulds and cannot be precisely identified but are evidently membraniporimorph cheilostomes. By comparison with similar modern cheilostomes, the colonies are estimated to have taken a week or more to grow to their preserved sizes. From this it can be inferred that the encrusted leaves remained intact and may potentially have been transported several kilometres from the site of origin. Without other evidence, the presence of articulated compound leaves is an insufficient criterion for inferring the autochthonous or parautochthonous nature of plant megafossil assemblages. □ Bryozoa, Cretaceous, Taphonomy, Lower Silesia, Poland, Europe, Angiosperms.