Camarasaurus (/ˌkæmərəˈsɔːrəs/ KAM-ər-ə-SOR-əs) was a genus of quadrupedal, herbivorous dinosaurs and is the most common North American sauropod fossil. Its fossil remains have been found in the Morrison Formation, dating to the Late Jurassic epoch (Kimmeridgian to Tithonian stages), between 155 and 145 million years ago.
Camarasaurus presented a distinctive cranial profile of a blunt snout and an arched skull that was remarkably square, typical of basal Macronarians.
The name means "chambered lizard", referring to the hollow chambers, known as pleurocoels, in its cervical vertebrae (Greek καμαρα (kamara) meaning "vaulted chamber", or anything with an arched cover, and σαυρος (sauros) meaning "lizard").
Camarasaurus contains four species that are commonly recognized as valid: Camarasaurus grandis, Camarasaurus lentus, Camarasaurus lewisi, and Camarasaurus supremus. C. supremus, the type species, is the largest and geologically youngest of the four. Camarasaurus is the type genus of Camarasauridae, which also includes its European close relative Lourinhasaurus.
Camarasaurus was named in 1877 by Edward Drinker Cope, during the period of scientific rivalry between him and Othniel Charles Marsh known as the Bone Wars. Soon after, Marsh named a genus Morosaurus, but it was subsequently shown to be synonymous with Camarasaurus.The first record of Camarasaurus comes from the spring of 1877 when Mr. Oramel William Lucas of Cañon City, Colorado discovered some large vertebrae at Garden Park, which he sent to Edward Drinker Cope who was based in Philadelphia, Pennsylvania.The original material sent consisted of a partial cervical vertebra, which would become the taxon's namesake, three dorsal vertebrae, and four caudal vertebrae.This specimen is now thought to have been composed of several individuals.From these initial fragmentary remains, Cope made his original description of Camarasaurus supremus (“supreme chambered lizard”) and founded the genus; these remains are now in the American Museum of Natural History under the catalogue number AMNH 560.After receiving the original bones, Cope employed collectors who gathered more of the material which was described in 1921 by Henry Osborn and Charles Mook.The amount of material was great, it composed of several jumbled partial skeletons.It was not all prepared at once, but a considerable amount of it was cleaned up by Jacob Geismar under Cope's direction throughout the 1870s to 1890s.In 1877 a reconstruction of the skeleton of Camarasaurus was painted by Dr. John Ryder on several canvasses, under the direction of Professor Cope who would use them in lectures to impress his audience. This reconstruction would be the first ever made of a sauropod dinosaur, was natural size and represented the remains of a number of individuals. The reconstruction was over fifty feet in length. Cope's collectors sent in more material from 1877 to 1878,and as Cope would get more material, he would name taxa based on these newly sent remains. Most of these additional taxa are now considered dubious or synonymous with Camarasaurus.By the end of collecting in Garden Park, at least four individuals and several hundred bones had been found from nearly every part of the skeleton.The next Camarasaurus discovery came later in 1877, when a fragmentary posterior skull and a partial postcranial skeleton was discovered and collected in Quarry 1, Como Bluff, Wyoming by crews working for Othniel Charles Marsh. This skeleton would be the best preserved single individual of Camarasaurus at the time, and it was named as a new species of Apatosaurus in 1877. The specimen was not fully collected until 1879 and the specimen contains the majority of a juvenile's skeleton (holotype YPM 1901) Meanwhile, crews working for Edward Cope in Garden Park, collected a fragmentary specimen consisting of a femur and 2 caudal vertebrae was made a new species of Amphicoelias by Cope which he named Amphicoelias latus in 1877.This species was tentatively synonymized with C. supremus in 1921. In 1998, Kenneth Carpenter argued that the stratigraphic position of the find suggested it was more likely to be synonymous with C. grandis,but in a 2005 study of the biostratigraphic distribution of Camarasaurus, Takehito Ikejiri retained it in synonymy with C. supremus.In 1878, a sauropod sacrum was discovered with several other jumbled sauropod postcranial elements, again at Como Bluff. The remains were also sent to Marsh and in 1878 the sacrum was assigned to a new genus and species, Morosaurus impar ("unpaired stupid lizard"). Morosaurus would receive several new species throughout the late 19th century, even becoming part of a new family in 1892, the Morosauridae. A majority of Morosaurus species are now considered dubious, including the type species, or reclassified.In 1889, a new species of Morosaurus was named based on a partial skull and skeleton from Como Bluff.
