Selmasaurus is a genus of medium-sized plioplatecarpine mosasaur from the Upper Cretaceous Mooreville Chalk Formation (Campanian) of western Alabama (United States). First recognized by geologist Samuel Wayne Shannon in his 1975 Master's thesis, "Selected Alabama Mosasaurs," the taxon remained a nomen nudum until it was officially described in 1988 ("A new plioplatecarpine mosasaur (Squamata, Mosasauridae) from Alabama", Journal of Vertebrate Paleontology, Vol. 8, No. 1, 31 March 1988) in an article coauthored by Shannon and paleontologist Caitlin R. Kiernan. The type specimen, formerly reposited at the Geological Survey of Alabama and cataloged as GSATC 221, was transferred in 2005 to the Alabama Museum of Natural History (Tuscaloosa). The holotype consists of a very well-preserved but in