Remains of Clidastes Cope, 1868, an unexpected mosasaur in the upper Campanian of NW Germany

Abstract

The mosasaurine Clidastes sp. is recognised from cranial and post-cranial remains collected at four localities in NW Germany. Cranial material was found in pelagic turbiditic marls which crop out near the village of Beckum, while post-cranial skeletal elements were collected from sandy limestones exposed near the villages of Schöppingen, Coesfeld and Billerbeck. In stratigraphic order, the units producing these specimens of Clidastes are the Coesfeld, Baumberge and Beckum formations of late Campanian (Late Cretaceous) age. The cranial material comprises the anterior part of a skull and a single isolated tooth, while post-cranial bones comprise a few isolated vertebrae and a partial skeleton including forelimb bones and an articulated vertebral column. Clidastes is known to date from the western North Sea Basin (England), southern Sweden, as well as from North America (Western Interior Seaway and Gulf Coast).