Costacopluma (Decapoda: Brachyura: Retroplumidae) from the Maastrichtian and Paleocene of Senegal: A survivor of K/Pg events Matú  s Hy  zný a, b, * , Vincent Perrier c , Ninon Robin d , Jeremy E. Martin e , Rapha € el Sarr f a Department of Geology and Palaeontology, Natural History Museum, Vienna, Burgring 7, A-1010 Vienna, Austria b Comenius University, Faculty of Natural Sciences, Department of Geology and Palaeontology, Ilkovi cova 6, SVK-842 15, Bratislava, Slovakia c Department of Geology, University of Leicester, LE1 7RH Leicester, United Kingdom d Centre de recherche sur la Pal eobiodiversit e et les Pal eoenvironnements, MNHN, SU, UPMC, CNRS, 8 rue Buffon, 75005 Paris, France e Laboratoire de G eologie de Lyon: Terre, Plan ete, Environnement, UMR CNRS 5276 (CNRS, ENS, Universit e Lyon1), Ecole Normale Sup erieure de Lyon, 69364 Lyon Cedex 07, France f Laboratoire de S edimentologie et Biostratigraphie, D epartement de G eologie, Universit e Cheikh Anta Diop de Dakar, Senegal article info Article history: Received 25 June 2015 Received in revised form 3 August 2015 Accepted in revised form 22 August 2015 Available online xxx Keywords: Decapoda Retroplumidae K/Pg boundary Cuticle microstructure Palaeobiogeography abstract Newly collected decapod material from the Cap de Naze Formation (middleeupper Maastrichtian), Senegal, allows description of a new species of Costacopluma (Brachyura: Retroplumidae), which is older than Costacopluma senegalensis (Remy in Gorodiski & Remy, 1959) from the Paleocene of Senegal and documents that the genus survived the end Cretaceous event in the same area. The holotype of Cos- tacopluma mamethioupamei n. sp. is preserved both in dorsal and ventral aspects, and it bears a strange dumbbell-shaped “scar” on sternite 4 which is tentatively interpreted as a true epibiont mark or remain, which encrusted the crab cuticle syn-vivo or post-mortem; the identification of the tracemaker is obscured. The cuticular microstructure of Costacopluma mamethioupamei n. sp. is documented using SEM imaging. The cuticle appears to be preserved in its entirety and areas with damaged cuticle shows several distinct layers interpreted as endocuticle, exocuticle and epicuticle. Thanks to the present report of Costacopluma mamethioupamei n. sp. it is now clear that the genus survived the K/Pg boundary not only in the area of the Gulf of Mexico (as documented by several previously published reports) but also in the present-day Senegal. From the palaeobiogeographic perspective, it is interesting to note, that the African continent has been inhabited only with narrow-ridged species of Costacopluma, including Costacopluma concava Collins & Morris, 1975, C. senegalensis and C. mamethioupamei n. sp. This lineage may finally lead to the origin of Tethyan retroplumids, which were widely distributed across Europe during the Eocene. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction The mass extinction at the end of the Cretaceous period (K/Pg boundary) is a celebrated event in the history of life leading to a complete restructuring of terrestrial and marine ecosystems. Among invertebrates, Sheehan, Coorough, and Fastovsky (1996) suggested that arthropods have preferentially survived the K/Pg event because of their detritus-feeding habit. Schweitzer and Feldmann (2005) studied more closely the effects of this cata- strophic event on decapod crustaceans and concluded that no major extinction could be detected in the fossil record of decapods. Regarding the possible impact of the event on the structure of decapod assemblages (e.g. average carapace size changes due to stressed environment), it has not been studied rigorously so far (for the evolutionary trends in the body size of decapods see Klompmaker, Schweitzer, Feldmann, & Kowalewski, 2015). Based on the data presented by Schweitzer and Feldmann (2005), at least 42 brachyuran genera are known from the upper Maastrichtian strata, of which at least 12 (28.6%) survived the K/Pg event with Costacopluma Collins & Morris, 1975, among them. Costacopluma was first described from the Upper Cretaceous of Nigeria (Collins & Morris, 1975) and since then has been reported from many parts of the world spanning the Coniacian (Upper Cretaceous) to the Eocene. Thirteen species have been described until now (Oss o-Morales, Artal, & Vega, 2010). Based on newly recovered material from the Maastrichtian of Senegal, this * Corresponding author. Natural History Museum, Vienna, Burgring 7, A-1010 Vienna, Austria. E-mail address: hyzny.matus@gmail.com (M. Hy zný). Contents lists available at ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes http://dx.doi.org/10.1016/j.cretres.2015.08.010 0195-6671/© 2015 Elsevier Ltd. All rights reserved. Cretaceous Research 57 (2016) 142e156