Bivalve borings in Maastrichtian fossil Nypa fruits: Dakhla Formation, Bir Abu Minqar, South Western Desert, Egypt

Abstract

Disconnected aggregates of allochthonous fossil Nypa fruits occur in the Ammonite Hill Member of the Dakhla Formation (Maastrichtian), exposed at the Bir Abu Minqar section, south Western Desert of Egypt. In a pale brown, calcareous siltstone and/or fine-grained sandstone layer, the fossil fruits found are densely infested by the borings Teredolites clavatus and Apectoichnus longissimus. In the specimens described, wood borings assigned to A. longissimus are more abundant than T. clavatus. Remains of the boring bivalves are not preserved. These aggregates of bored fruits likely accumulated in a warm, shallow, well-oxygenated marine environment. Prior to final accumulation, Nypa fruits drifted in seawater only for a short time and exhibit evidence of biostratinomic alterations. The present study is the first to systematically describe the occurrence of both nominal ichnotaxa from the Maastrichtian rocks in Egypt.