Calamopleurus is a prehistoric genus of marine halecomorph ray-finned fish from the Early Cretaceous of South America and northern Africa. It was a relative of the modern bowfin, with both belonging to the family Amiidae. It contains three species: It is thought to be the sister genus to Maliamia, the last surviving member of the vidalamiines, which is the largely marine amiid group that also contained Calamopleurus. Both are placed in the tribe Calamopleurini. C. cylindricus was among the largest known amiids, rivaling the giant Paleocene bowfin Amia pattersoni in size. However, both were slightly smaller than Melvius and Amia basiloides, the two largest known amiids. It is one of the earliest known amiids to evolve a large body size.