Middle Eocene echinoids from El Sheikh Fadl-Ras Gharib stretch, Eastern Desert, Egypt: systematics, stratigraphy, palaeobiogeography

Twenty-two echinoid species (5 regular and 17 irregular) belonging to 14 genera, 10 families, 5 orders, and 3 subclasses are identified from the Middle Eocene succession cropping out in El Sheikh Fadl-Ras Gharib stretch, Eastern Desert. The echinoid fauna studied herein came from four sections: Gebel ElMehasham, South Gebel ElMehasham, Gebel ElMereir, and Gebel Qarara sections. The studied succession consists of three formations, from base to top Muweilih, Midawara, and Sath ElHadid, spanning the Middle Eocene (Lutetian and Bartonian), Lower-Middle Mokattamian (levels MK3 to MK6). The highest species diversity is recorded in the Midawara Formation (21 species), while the Muweilih Formation is barren of echinoid species. Four species are recorded for the first time in the studied area: Echinolampas cf. bastai Elattaar and Strougo 2001; Schizaster isidis Stefanini Boll Soc Geol Ital 38:39–63, 1919; Gillechinus humei (Fourtau 1908); and Eupatagus lefebvrei (de Loriol Memoires de la Societe de Physique et d’Histoire Naturelle de Geneve 27:58–148, 1880). One species consider to be new, Schizaster sp. (n. sp). Thirteen species are endemic to Egypt, and nine are common elsewhere in the world, in some countries of Europe, Africa, and Asia. Predation and malformation in growth are observed in two species: Schizaster humei Fourtau Mémoires de l’Institut Egyptien 6(2):93–175, 1909b and Eupatagus cossmanni (Lambert Mém Soc Géol Fr, Paléontol 9:1–57, 1902) as a shallow infaunal species. All the identified echinoid fauna herein has been examined and systematically described with the aim to know their stratigraphic and paleogeographic distribution.