Barosaurus

Barosaurus ("heavy lizard") is a genus of large sauropod dinosaur that lived in present-day North America during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1890. The genus contains a single valid species, B. lentus, though the African species B. africanus has since been assigned to Tornieria. B. lentus' holotype (name-bearing) specimen initially consisted of four caudal (tail) vertebrae that were found in 1889 in South Dakota by Ms. Isabella R. Ellerman. However, later excavations found vertebrae, limb bones, and other postcranial remains from the same individual. Several other specimens have been collected outcrops of the Morrison Formation in Utah and Montana, though fossils potentially from the genus have been reported from Colorado, Wyoming, and Oklahoma as well. Barosaurus is known from the Kimmeridgian stage of the Late Jurassic period, which dates to around 152 to 150 million years ago. Barosaurus was an enormous animal, with some adults measuring about 25–27 m (82–89 ft) in length and weighing about 12–20 metric tons (13–22 short tons). This makes it among the largest diplodocid sauropods. In comparison to its close kin Diplodocus, Barosaurus has a relatively longer neck but shorter tail. Despite this, the tail composed around half the total length of the animal. Barosaurus has 16 cervical vertebrae, more than Diplodocus and Apatosaurus, which are extremely elongated. The back was more compact, with only nine dorsal vertebrae. Barosaurus is a member of the family Diplodocidae, a group of long-tailed sauropods that lived during the Jurassic. The Morrison Formation had a floodplain environment with hot summers and moderate winters. The strata of the Morrison Formation bears a variety of other fossils, including an array of dinosaurs. This includes the theropods Allosaurus and Ceratosaurus, ornithischians Stegosaurus and Dryosaurus, and the other sauropods Brachiosaurus and Brontosaurus.

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