Brancasaurus

Brancasaurus is a genus of plesiosaur that lived during the Berriasian stage of the Early Cretaceous period in what is now Germany. The only known species is B. brancai, first described in 1914 from a relatively complete fossil skeleton discovered four years earlier near Gronau, North Rhine-Westphalia. The scientific name of the taxon honours the German paleontologist Wilhelm von Branca. The holotype skeleton represents the most complete Early Cretaceous plesiosaur specimen known from Europe. Another, more fragmentary skeleton of the same taxon was assigned to the newly erected genus Gronausaurus in 2013, before being recognized as a junior synonym of Brancasaurus in a revision published three years later. Additional specimens assigned or potentially referable to Brancasaurus have been recovered from the type locality and from Lower Saxony, some of which had previously been referred to the genus Plesiosaurus by Ernst Koken.

With a long neck possessing vertebrae bearing distinctively-shaped "shark fin"-shaped neural spines, and a relatively small and pointed head, Brancasaurus is superficially similar to elasmosaurids, a group to which it was long assigned. It differed, however, by its more reduced size, the probable subadult holotype measuring 3.26 metres (10.7 ft) in length. Since 2010, several phylogenetic analyses have recovered Brancasaurus as a member, or a close relative, of the Leptocleididae. Fossil remains of Brancasaurus originates from deposits who likely represented a large continental freshwater lake.