Opetiosaurus bucchichi was a small, approximately 1 meter (3.3 feet) long, relative of mosasaurids, the aquatic predatory squamates including, among others, the 17 meters (55 feet) long Mosasaurus hoffmanni. Opetiosaurus lived at the early phase of the Late Cretaceous, around 94 to 93 million years ago in what is now the island of Hvar, Croatia, and represented the early stage of mosasaur evolution as its limbs were still not yet fully adapted to an aquatic lifestyle.
A 2009 study by Alex Dutchak and Michael Caldwell suggests that Opetiosaurus should actually be called Aigialosaurus because the species O. bucchichi shares many similarities to Aigialosaurus dalmaticus that lived at the same place and time. Opetiosaurus is kept separate here because current analyses of phylogenetic relationships do not necessarily suggest such close evolutionary connections.
Featured image by Michael B. H. CC BY-SA 3.0.