Bioerosion in the middle Eocene larger foraminifer Nummulites in the Fayum depression, Egypt Zaki A. Abdel-Fattah Geology Department, Faculty of Science, Damietta University, New Damietta City, 34517, Damietta, Egypt A R T I C L E I N F O Article history: Received 14 April 2018 Received in revised form 8 August 2018 Accepted 9 August 2018 Available online xxx A B S T R A C T The present paper focuses for the first time on the trace fossils present in carbonate tests of the famous Egyptian middle Eocene larger foraminifer Nummulites gizehensis group. Bioerosion is represented by a unique diversified assemblage of seven ichnospecies belonging to four ichnogenera. Diagnostic drilling holes of the ichnogenus Oichnus are represented by the three ichnospecies O. simplex, O. paraboloides and O. asperus. Rare spiral galleries of Trypanites helicus and sinuous tunnels of Maeandropolydora sulcans were identified. Simple U-shaped borings of Caulostrepsis taeniola and Caulostrepsis isp. were also recognized within the studied nummulites. The reported drilling holes are attributed essentially to the predation of gastropods, whereas the other recognized galleries are assigned mainly to boring activities of the polychaete worms. Well-preserved tests with rare bioerosion and encrustation indicate deposition under a high rate of sedimentation and no prolonged transportation. Conversely, taphonomic characteristics of the bioeroded and encrusted nummulites can be used as good palaeoecological indictors of a deposition under low to fair rate of sedimentation. Coexistence of non-bioeroded and bioeroded/encrusted tests, common thick-bedded nummulite wackestone and packestone, predomi- nated larger and flat Nummulites spp., and non-preferred imbrications are taken altogether with the reported ichnological assemblage to suggest that the nummulites were accumulated in situ and/or under weak influence of physical processes (storm and waves) in a shallow-marine environment, possibly middle to inner carbonate ramps. © 2018 The Geologists' Association. Published by Elsevier Ltd. All rights reserved. 1. Introduction Bioerosion is widely used in taphonomic and palaeoecologic interpretations in the rock record (Taylor and Wilson, 2003; Abdel-Fattah and Assal, 2016). Taphonomy and depositional modeling of the widespread Eocene nummulite accumulations along the margins of Tethys (e.g., Oman, Iran, Egypt, Libya, Tunisia, Italy and Spain) has been the subject of many publications (see Arni and Lanterno, 1972; Decrouez and Lantrno, 1979; Aigner, 1982; Racey, 2001; Beavington-Penney et al., 2005, 2006; Bassi and Nebelsick, 2010; Bassi et al., 2013; Seddighi et al., 2015; Hadi et al., 2016; Pomar et al., 2017). Bioerosion in calcareous foraminiferal tests has been discussed both spatially and temporarily (Livan, 1937; Sliter, 1971; Bromley, 1981; Hickman and Lipps, 1983; Arnold et al., 1985; Shroba, 1993; Nielsen, 1999; Nielsen and Nielsen, 2001). Calcareous tests of the Mesozoic and Cenozoic larger benthic foraminifera (LBF) represent typical substrates for diverse micro- and macro-borers (Golubic et al., 1984; Nielsen, 2002; Nebelsick et al., 2011;  Cosovi c et al., 2012; Schlagaintweit et al., 2013). Bioerosion of the larger foraminifer Nummulites has received less attention in comparison with other benthic and planktonic foraminifera. Nielsen and Görmüş (2004) defined pascichnial trackways of Maeandropoly- dora osmaneliensis in the tests of the Maastrichtian Orbitoides sp. and Trypanites helicus in tests of the Eocene larger foraminifera Nummulites of western Turkey. Later, Sengupta and Nielsen (2009) recognized cylindrical borings of Oichnus simplex in the middle Eocene Nummulites obtusus (Sowerby) from India. The current work focuses for the first time on the bioerosion in the carbonate tests of the middle Eocene Nummulites spp., which belong to the Nummulites gizehensis group. A taxonomic analysis of this widespread foraminiferal group is out the scope of the present paper. Nummulites gizehensis was identified and named for the first time by Forskål (1775) at the Plateau of Pyramids in Giza. Later studies proposed that Nummulites gizehensis (Forskål) comprised many taxa and suggested the term races or groups for these similar subdivisions (e.g., D’Archiac and Haime, 1853; de la Harpe, 1883; Said, 1951; Kenawy, 1978; Schaub, E-mail addresses: zaki.abdelfattah@du.edu.eg, zabdelfattah@gmail.com (Z.A. Abdel-Fattah). https://doi.org/10.1016/j.pgeola.2018.08.003 0016-7878/© 2018 The Geologists' Association. Published by Elsevier Ltd. All rights reserved. Proceedings of the Geologists’ Association xxx (2018) xxx–xxx G Model PGEOLA 712 No. of Pages 8 Please cite this article in press as: Z.A. Abdel-Fattah, Bioerosion in the middle Eocene larger foraminifer Nummulites in the Fayum depression, Egypt, Proc. Geol. Assoc. (2018), https://doi.org/10.1016/j.pgeola.2018.08.003 Contents lists available at ScienceDirect Proceedings of the Geologists’ Association journa l homepage : www.e lsevier.com/loca te/pgeola