Early Campanian mosasaurs (Reptilia; Mosasauridae) from the Kristianstad Basin, southern Sweden

Abstract: Marine strata of latest early Campanian age from the Kristianstad Basin in Skåne, southern Sweden, have yielded a diverse mosasaur fauna comprising four taxa: Clidastes? sp., Platecarpus cf. somenensis, Hainosaurus? ivoensis and Mosasauridae sp. The material consists primarily of isolated tooth-crowns, although a number of incomplete vertebrae and cranial elements have been recorded as well. Based on the collections of mosasaur remains from four localities, i.e. Åsen, Ignaberga, Maltesholm and Ugnsmunnarna, some differences in the distribution of mosasaur taxa within the Kristianstad Basin have been observed. Clidastes? sp. is the predominant mosasaur in the near-shore deposits at Åsen, whereas the Ugnsmunnarna site, with a more open water environment, has yielded mainly Platecarpus cf. somenensis. The assemblage is similar in composition to approximately coeval mosasaur faunas in the Upper Chalk deposits in Norfolk, Sussex and Hampshire, England, the Lower Pierre Shale in South Dakota, USA and the Pembina Member of the Pierre Shale in Manitoba, Canada. Hainosaurus? ivoensis was formerly believed to be a species of Mosasaurus (i.e. M. cf. hoffmanni, M. hoffmanni ivoensis and M. ivoensis of previous writers). Tooth-crowns of Mosasauridae sp. are fairly large, strongly recurved and covered by smooth enamel. As this combination appears to be unique, Mosasauridae sp. may represent a new genus.