ORTHOPHRAGMINIDS (FORAMINIFERA) ACROSS THE PALEOCENE–EOCENE TRANSITION FROM NORTH AFRICA: TAXONOMY, BIOSTRATIGRAPHY, AND PALEOBIOGEOGRAPHIC IMPLICATIONS ERCAN O ¨ ZCAN 1,4 ,CHRISTIAN SCHEIBNER 2 AND KAMEL BOUKHALFA 3 ABSTRACT The platform margin and slope deposits in Galala, Egypt, record a larger benthic foraminiferal turnover (LFT), previously proposed to coincide with the Paleocene-Eocene (P/E) boundary based on the negative carbon isotope excursion (CIE) consistent with the Paleocene-Eocene Thermal Maximum (PETM). The LFT in these deposits was established on the basis of supposed synchronous first appearances of such taxa as Alveolina, Nummulites, and Orbitolites at or around the P/E boundary, although the response of orthophragminids, assigned only to the genus Discocyclina, was not studied. The orthophragminids in the late Paleocene–early Eocene interval in some of these deposits (sections B3, D5, D6, and D8) are represented by species of Discocyclina Gu ¨mbel, Orbitoclypeus Silvestri, and Nemkovella Less, reported for the first time from the southern margin of the Tethys. The Thanetian orthophrag- minids consist of Orbitoclypeus multiplicatus, O. schopeni, Discocyclina seunesi, and D. tenuis, while assemblages in the early Eocene are characterized by Discocyclina archiaci, D. dispansa, Orbitoclypeus schopeni, and Nemkovella stockari, suggesting a significant change in composition through the sections. The assemblages below and above the P/E boundary, only recorded in sections B3 and D8, mark the orthophrag- minid zones OZ 1B and 3, respectively. The OZ 2, correlated to shallow benthic zones SBZ 5 and 6 in the basal part of the Eocene and recognized by the first appearance of asterocy- clinids, nemkovellids, and some ribbed orbitoclypeid species in northern Tethyan platforms, was not found. This may suggest either a hiatus, recorded previously in section D8 based on calcareous plankton, across the P/E transition in section B3 or an artifact of sampling. Consequently, our data raise some doubts about the aforementioned compositional changes related to the LFT and P/E boundary. We discovered an advanced developmental stage of N. stockari (N. stockari bejaensis n. subsp.) from a new section in Tunisia. This subspecies seems to be a key taxon for the early Eocene of the southern Tethyan platforms and extends the geographic and stratigraphic range of the species. We conclude that orthophragminids at Galala bear a close resemblance to those in the northern Tethyan platforms, especially assem- blages from Turkey. INTRODUCTION The Paleocene-Eocene (P/E) boundary is a well-studied portion of geological time that now is correlated globally on the basis of a significant negative carbon isotope excursion (CIE), recognized in both marine and terrestrial systems (Aubry et al., 2007, and references therein). The carbon excursion was linked to a global-warming event, namely the Paleocene-Eocene Thermal Maximum (PETM; Zachos et al., 2001), and is associated with significant paleontologic changes. In marine systems, the response of deep-sea benthic and planktonic foraminifera and dinoflagellates to the warming event is recognized by major modifications in composition, diversity, and abundance, and the synchronity of these events provide a sound basis for regional and global correlations across the P/E boundary. One of the most notable CIE biotic events, involving the extinction of many deep-sea benthic foraminifera, is known as the benthic extinction event or BEE (Thomas, 2003, 2007, and references therein). It involved a main extinction phase during the CIE, domination of opportunistic taxa, and a prominent turnover in the composition of foraminifera inhabiting the bathyal and abyssal sea bottom. The extinction of benthic foraminifera in outer-shelf environ- ments, however, was a minor event (Speijer et al., 1995, 2012; Aubry et al., 2007). The larger benthic foraminifera (LBF) are major contributors to shallow-marine sediments in the tropic and subtropics during the early Paleogene, and occasionally they formed prolific accumulations along the northern and southern margins of the Tethys (Hottinger, 1960; Drobne, 1977; Schaub, 1981; Racey, 2001; O ¨ zcan, 2002). In addition to some stratigraphically important groups such as miscellanids and rotaliids (Hottinger, 2009), the nummuli- tids, alveolinids, and orthophragminids constitute a rea- sonable portion of the LBF in the platform deposits during the P/E transition (Serra-Kiel et al., 1998). Because of the uncertainties in the delineation of the P/E boundary and its correlation to the Ypresian and Ilerdian stages, the exact distribution of these groups with respect to the P/E boundary has remained ambiguous (Molina et al., 1992). The concept of a boundary interval zone, spanning ,1 Myr, was adopted in the shallow benthic zonation (SBZ) scheme of Serra-Kiel et al. (1998), in which a major turnover in LBF takes place in the interval corresponding to SBZ 5/6 (Fig. 1). In fact, a similar but less pronounced trend occurring around the loosely defined P/E boundary was recognized much earlier in alveolinids and nummulitids (Hottinger, 1960; Hottinger & Schaub, 1960; Schaub, 1981), based on the first appearances of Alveolina spp., true involute Nummulites spp., and Orbitolites sp. in SBZ 5, which was placed at the base of the Ilerdian and in the upper part of the late Thanetian by Serra-Kiel et al. (1998). Journal of Foraminiferal Research fora-44-03-01.3d 21/5/14 01:27:42 203 Cust # 2198 1 I ˙ stanbul Technical University, Faculty of Mines, Department of Geological Engineering, Ayazag ˘a 34469, I ˙ stanbul, Turkey 2 Universita ¨t Bremen, FB5, P.O. Box 330440, 28334 Bremen, Germany 3 Universite ´ de Gabe `s, Faculte ´ des Sciences de Gabe `s, Cite ´ Riadh, Zirig 6072 Gabe `s, Tunisia 4 Correspondence author. E mail: ozcanerc@itu.edu.tr Journal of Foraminiferal Research, v. 44, no. 3, p. 203–229, July 2014 203