species of Camarasaurus in 1996. Some researchers have suggested that Cathetosaurus should be reinstated as a distinct genus, whereas others have suggested that C. lewisi may be synonymous with another Camarasaurus species. C. supremus, as its name suggests, is the largest known species of Camarasaurus and one of the most massive sauropods known from the late Jurassic Morrison Formation. Except for its huge size, it was nearly indistinguishable from C. lentus. C. supremus was not typical of the genus as a whole, and is known only from the latest, uppermost parts of the formation and is extremely uncommon. Both C. grandis, C. lentus, and C. lewisi were smaller, as well as occurring in the earlier stages of the Morrison. Stratigraphic evidence suggests that chronological sequence aligned with the physical differences between the three species, and it describes an evolutionary progression within the Morrison Formation. C. grandis is the oldest species and occurred in the lowest rock layers of the Morrison. C. lewisi only briefly coexisted with C. grandis in the lowest strata of the upper Morrison until going extinct, but it is possible this is because of a lack of specimens from C. lewisi. C. lentus appeared later, co-existing with C. grandis for several million years, possibly due to different ecological niches as suggested by differences in the spinal anatomy of the two species. At a later stage, C. grandis disappeared from the rock record, leaving only C. lentus. Then C. lentus, too, disappeared; at the same time, C. supremus appeared in the uppermost layers. This immediate succession of species, as well as the very close similarity between the two, suggests that C. supremus may have evolved directly from C. lentus, representing a larger, later-surviving population of animals. Synonyms and dubious species Amphicoelias latus was named by Edward Cope in 1877 based on a right femur and 4 caudal vertebrae found at Garden Park and is synonymous with either C. supremus or C. grandis. Caulodon diversidens was also named by Cope in 1877 on, now dubious, teeth that can only be placed as a Macronarian or as synonymous with Camarasaurus supremus. Caulodon leptoganus was named in 1878 by Cope on 2 partial teeth and is also considered to be unclassifiable beyond Macronaria or as synonymous with Camarasaurus supremus. Morosaurus impar was named by Marsh in 1878 as the type species of Morosaurus, and the material consisted only of a sacrum