The Mammals of the Late Eocene – Early Oligocene Solent Group

Part 1 begins a systematic account of the mammals from the British Solent Group. Their previous study is summarised. The stratigraphy is reviewed and lithostratigraphic logs are provided for the mammal-bearing localities. The new Fort Victoria Member replaces the previous restricted use Cliff End Member in the Headon Hill Formation. Seventeen species-group taxa of the placental euarchontan family Nyctitheriidae are described, with the new genera Actinyctia and Cheilonyctia and the new species Amphidozotherium gassoni, Actinyctia bulbodens, Cheilonyctia lawsoni, Scraeva yulei, Euronyctia curranti and E. plesiolambda. The occurrence of Saturninia mamertensis near the base of the Headon Hill Formation extends its range from the Bartonian to early Priabonian. The occurrence of Oligonyctia hoffmani in the Bembridge Limestone Formation and lower Hamstead Member extends its range from the early Rupelian to the late Priabonian. A phylogenetic analysis of European Bartonian–Rupelian Nyctitheriidae results in an expanded subfamily Amphidozotheriinae and a new subfamily Saturniniinae for Saturninia (s.s.), Cryptotopos and Oligonyctia. Cryptotopos communis and Euronyctia recta from the German Oligocene are transferred to the genus Paradoxonycteris, whilst Sigenyctia (type species S. oligocaena) is synonymised with the genus Euronyctia. Saturninia mamertensis and S. grandis are shown not to be members of this genus. Euronyctia curranti, E. plesiolambda and E. oligocaena form a stratigraphical morphocline, suggestive of an evolutionary sequence. A phylogenetic analysis of primitive eutherians confirms Nyctitheriidae as stem members of the superorder Euarchonta, supporting an earlier analysis. Aspects of evolution, faunal turnovers and diversity of locomotor adaptations during deposition of the Solent Group are discussed.