Skeletons have also been discovered with gastroliths, stones, in their stomachs, though whether to help break down food, especially cephalopods, in a muscular gizzard, or to vary buoyancy, or both, has not been established. However, the total weight of the gastroliths found in various specimens appear to be insufficient to modify the buoyancy of these large reptiles. The first plesiosaur gastroliths, found with "Mauisaurus gardneri", were reported by Harry Govier Seeley in 1877. The number of these stones per individual is often very large. In 1949, a fossil of "Alzadasaurus" (specimen SDSM 451, later renamed to "Styxosaurus") showed 253 of them. Also, the size of individual stones is often considerable. In 1991 an elasmosaurid specimen was investigated, KUVP 129744, containing a gastrolith with a diameter of seventeen centimetres and a weight of 1.3 kilogramme; and a somewhat shorter stone of 1490 gram. In total forty-seven gastroliths were present with a combined weight of thirteen kilogramme. The size of the stones has been seen as an indication that they were not swallowed by accident but deliberately, the animal perhaps covering large distances in search of a suitable rock type.