Remains of the mosasaur Clidastes propython in marine strata of latest early Campanian age from the Kristianstad Basin, southern Sweden, represent the first record of Clidastes outside of North America. The material consists of shed marginal and pterygoid tooth-crowns, and vertebrae (including eleven associated cervicals and dorsals from a juvenile). The majority of the teeth and skeletal elements can be referred to juveniles (mostly in the estimated 2-3 m total body length range), but large, presumably adult individuals (up to an estimated total length of 6 m ) are also represented. Available data indicate that the Kristianstad Basin population of C. propython represents a short-lived migration, most likely from the Mississippi Embayment in North America. The local extinction of Clidastes in southern Sweden, tentatively placed at the early/late Campanian boundary (sensu germanico), may coincide with that in the Western Interior Seaway and Gulf Coast of North America. Within the Kristianstad Basin area, Clidastes occurs in high-energy, shallow water deposits, where it is the most common mosasaur. This finding is in stark contrast to recent publications suggesting that Clidastes inhabited mainly off-shore, deeper waters.

Key words: Reptilia, Mosasauridae, Clidastes, teeth, vertebrae, Cretaceous, Campanian, Sweden.

Johan Lindgren johan.lindgren@geol.lu.se], Department of Geology, GeoBiosphere Science Centre, Lund University, Sölvegatan 12, SE−223 62 Lund, Sweden; Mikael Siverson [cardabiodon@iinet.net.au], 9 Portsea Rise, Mosmon Park, 6012 WA, Australia.