Camarasaurus

Camarasaurus (/ˌkæmərəˈsɔːrəs/ KAM-ər-ə-SOR-əs) is a genus of sauropod dinosaur that lived during the Late Jurassic in what is now the United States. Its fossils are primarily known from the Morrison Formation dating to the Kimmeridgian and Tithonian ages of the Jurassic, between 155 and 145 million years ago (mya). It was named by Edward Drinker Cope in 1877; it definitively contains three species, C. supremus, the type species, C. grandis, and C. lentus, while some researchers consider C. lewisi to be in its own genus, Cathetosaurus. The generic 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'). Hundreds of specimens have been excavated to date, including some nearly complete skeletons. It is among the best understood dinosaurs, with detailed studies of its anatomy, paleobiology, paleoecology, and more.

A medium-large sauropod, C. supremus is estimated to have been 23 m (75 ft) long and to have weighed 42.3 tonnes whereas C. lentus was only around 15 m (49 ft) long. Like other sauropods, it was quadrupedal, with a large body, long neck, and long tail. Its skull was large, tall, and boxy with a huge naris, in contrast to the low skulls of sauropods like Diplodocus and Apatosaurus. Camarasaurus teeth are distinct in their spoon-shaped teeth which bear continuous cutting edges. It had 13-14 teeth in the upper jaws and 13 teeth in the lower jaws, which were rapidly replaced. Camarasaurus was named during the Bone Wars, a scientific rivalry between paleontologists Edward Drinker Cope and Othniel Charles Marsh. Marsh assigned many species to his genus Morosaurus, including M. lentus and M. grandis which are now believed to be species of Camarasaurus.

Camarasaurus is a member of the group Macronaria, however its relationships with its relatives are uncertain and debated. Some paleontologists have grouped Camarasaurus with taxa like Tehuelchesaurus and Lourinhasaurus in the family Camarasauridae, whereas others believe it is the only member of Camarasauridae. Camarasaurus is thought to have been a medium browser, with a feeding height of 2 to 5 m (6 ft 7 in to 16 ft 5 in), and a selective feeder. The robust, large jaws of the genus indicate that it had a stronger bite than sauropods like diplodocids. This would allow for niche partitioning in the Morrison Formation where fossils of Camarasaurus are known, which preserves a menagerie of sauropods. It is among the most common sauropods in the formation and was adapted to many environments based on its wide distribution. Camarasaurus also lived alongside dinosaurs like Stegosaurus, Allosaurus, and Brachiosaurus.