Plesiosauria (Reptilia) sinémuriens de Lorraine belge

The Plesiosauria (Reptilia) from the Upper Sinemurian (Lower Jurassic, or Liassic) of Belgian Lorraine are described and discussed in the present paper. IRSNB R127, a fragmentary skeleton from Dampicourt, and Plesiomurus dewalquii VAN BENEDEN, 1871 are referred to the Family Elasmosauridae. IRSNB R128, a series of vertebrae discovered in Stockem, is referred to the Family Pliosauridae. This leads to an extension of the palaeogeographical distribution of both Families since the Lower Liassic.