Barosaurus

***Barosaurus*** (meaning "heavy lizard") was a giant, long-tailed, long-necked, plant-eating sauropod closely related to the more familiar *Diplodocus*. Remains have been found in the Morrison Formation from the Upper Jurassic Period of Utah and South Dakota. It is present in stratigraphic zones 2–5.

## Description

*Barosaurus* was an enormous animal, with some adults measuring about 25–27 meters (82–89 feet) in length and weighing about 12–20 metric tons (13–22 short tons). There are some indications of even larger individuals, such as the enormous vertebra from the BYU 9024 specimen, which is 1.37 meters (4.5 ft) long. Assuming it belongs to *Barosaurus*, this was an animal that was 48 meters (157 ft) long and around 66 metric tons (73 short tons) in weight making it one of the largest known dinosaurs, with a neck length of at least 15 meters (49 ft) according to Mike Taylor. In 2020 Molina-Perez and Larramendi estimated it to be slightly smaller at 45 meters (148 ft) and 60 metric tons (66 short tons). However, abstracts from SVP indicate an assignment of BYU 9024 under *Supersaurus*. *Barosaurus* was differently proportioned than its close relative *Diplodocus*, with a longer neck and shorter tail, but was about the same length overall. It was longer than *Apatosaurus*, but its skeleton was less robust.

Sauropod skulls are rarely preserved, and scientists have yet to discover a *Barosaurus* skull. Related diplodocids like *Apatosaurus* and *Diplodocus* had long, low skulls with peg-like teeth confined to the front of the jaws.

Most of the distinguishing skeletal features of *Barosaurus* were in the vertebrae, although a complete vertebral column has never been found. *Diplodocus* and *Apatosaurus* both had 15 cervical (neck) and 10 dorsal (trunk) vertebrae, while *Barosaurus* had only 9 dorsals. A dorsal may have been converted into a cervical vertebra, for a total of 16 vertebrae in the neck. *Barosaurus* cervicals were similar to those of *Diplodocus*, but some were up to 50% longer. The neural spines protruding from the top of the vertebrae were neither as tall or as complex in *Barosaurus* as they were in *Diplodocus*. In contrast to its neck vertebrae, *Barosaurus* had shorter caudal (tail) vertebrae than *Diplodocus*, resulting in a shorter tail. The chevron bones lining the underside of the tail were forked and had a prominent forward spike, much like the closely related *Diplodocus*. The tail probably ended in a long whiplash, much like *Apatosaurus*, *Diplodocus* and other diplodocids, some of which had up to 80 tail vertebrae.

The limb bones of *Barosaurus* were virtually indistinguishable from those of *Diplodocus*. Both were quadrupedal, with columnar limbs adapted to support the enormous bulk of the animals. *Barosaurus* had proportionately longer forelimbs than other diplodocids, although they were still shorter than most other groups of sauropods. There was a single carpal bone in the wrist, and the metacarpals were more slender than those of *Diplodocus*. *Barosaurus* feet have never been discovered, but like other sauropods, it would have been digitigrade, with all four feet each bearing five small toes. A large claw adorned the inside digit on the manus (forefoot) while smaller claws tipped the inside three digits of the pes (hindfoot).

## *Barosaurus* in The Amazing Dinosaur Adventure

Steve the *Barosaurus*Donna the *Barosaurus*