 However, "Cartorhynchus" would have likely swam at slower speeds requiring less efficiency, and the advantages of carangiform swimming in later, larger ichthyosauriforms were also offset by increased body size.Bed 633 of the Majiashan Quarry, the locality where "Cartorhynchus" was found, is a layer of grey argillaceous (clay-bearing) limestone located above the base of the Upper Member of the Nanlinghu Formation.It is defined above and below by layers of yellowish marls.