Barosaurus

*Barosaurus lentus*

* Timothy Bradley Artwork
* Robert F Walters Artwork

***Barosaurus*** is a species of very large sauropod that lived in Late Jurassic. It is related to *Diplodocus* and *Apatosaurus*. Like most of the other sauropod species in Diplodocidae, it has a long, slender neck, stout, column-like limbs, and a long whip-like tail.

One primary difference between *Barosaurus* and *Diplodocus* is that it has 16 neck vertebrae, as opposed to the usual 15. Also, the vertebrae were about a third longer in length than its relatives. *Barosaurus* fossils are found in the USA and Tanzania and the average skeleton is about 93 feet (29 meters) long. It is a candidate for being one of the largest, if not the largest land animal and dinosaur in history.

The composite term *Barosaurus* comes from the Greek words barys (βαρυς) meaning "heavy" and *sauros* (σαυρος) meaning "lizard"; thus "heavy lizard".

## Description

*Barosaurus* was an enormous animal, with some adults measuring more than 26 meters (85 feet) in length and weighing more than 20 metric tons (22 short tons). *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).

## Classification and systematics

*Barosaurus* is a member of the sauropod family Diplodocidae, and sometimes placed with *Diplodocus* in the subfamily Diplodocinae. Diplodocids are characterized by long tails with over 70 vertebrae, shorter forelimbs than other sauropods, and numerous features of the skull. Diplodocines like *Barosaurus* and *Diplodocus* have slenderer builds and longer necks and tails than apatosaurines, the other subfamily of diplodocids.

Below is a cladogram of Diplodocinae after Tschopp, Mateus, and Benson (2015).

The systematics (evolutionary relationships) of Diplodocidae are becoming better established. *Diplodocus* has long been regarded as the closest relative of *Barosaurus*. *Barosaurus* is monospecific, containing only the type species, *B. lentus*, while at least three species belong to the genus *Diplodocus*. Another diplodocid genus, *Seismosaurus*, is considered by many paleontologists to be a junior synonym of *Diplodocus* as a possible fourth species. *Tornieria* (formerly "Barosaurus" *africanus*) and *Australodocus* from the famous Tendaguru Beds of Tanzania in eastern Africa have also been classified as diplodocines. With its elongated neck vertebrae, *Tornieria* may have been particularly closely related to *Barosaurus*. The other subfamily of diplodocids is Apatosaurinae, which includes *Apatosaurus* and *Supersaurus*. The early genus *Suuwassea* is considered by some to be an apatosaurine, while others regard it as a basal member of the superfamily Diplodocoidea. Diplodocid fossils are found in North America, Europe, and Africa. More distantly related within Diplodocoidea are the families Dicraeosauridae and Rebbachisauridae, found only on the southern continents.

## Discovery and naming

The first *Barosaurus* remains were discovered in the Morrison Formation of South Dakota by Ms. Isabella R. Ellerman, postmistress of Postville, and excavated by Othniel Charles Marsh and John Bell Hatcher of Yale University in 1889. Only six tail vertebrae were recovered at that time, forming the type specimen (YPM 429) of a new species, which Marsh named *Barosaurus lentus*, from the Classical Greek words *βαρυς* (*barys*) ("heavy") and σαυρος (*sauros*) ("lizard"), and the Latin word *lentus* ("slow"). The rest of the type specimen was left in the ground under the protection of the landowner, Ms Rachel Hatch, until it was collected nine years later, in 1898, by Marsh's assistant, George Rieber Wieland. These new remains consisted of vertebrae, ribs and limb bones. In 1896 Marsh had placed *Barosaurus* in the Atlantosauridae; in 1898 it was by him classified as a diplodocid for the first time. In his last published paper before his death, Marsh named two smaller metatarsals found by Wieland as a second species, *Barosaurus affinis*, but this has long been considered a junior synonym of *B. lentus*.

After the turn of the 20th century, Pittsburgh's Carnegie Museum of Natural History sent fossil hunter Earl Douglass to Utah to excavate the Carnegie Quarry in the area now known as Dinosaur National Monument. Four neck vertebrae, each 1 meter (3 feet) long, were collected in 1912 near a specimen of *Diplodocus*, but a few years later, William Jacob Holland realized they belonged to a different species. Meanwhile, the type specimen of *Barosaurus* had finally been prepared at Yale in the winter of 1917 and was fully described by Richard Swann Lull in 1919. Based on Lull's description, Holland referred the vertebrae (CM 1198), along with a second partial skeleton found by Douglass in 1918 (CM 11984), to *Barosaurus*. This second Carnegie specimen remains in the rock wall at Dinosaur National Monument and was not fully prepared until the 1980s.

The most complete specimen of *Barosaurus lentus* was excavated from the Carnegie Quarry in 1923 by Douglass, now working for the University of Utah after the death of U.S. Steel founder Andrew Carnegie, who had been financing Douglass' earlier work in Pittsburgh. Material from this specimen was originally spread across three institutions. Most of the back vertebrae, ribs, pelvis, hindlimb and most of the tail stayed at the University of Utah, while the neck vertebrae, some back vertebrae, the shoulder girdle and forelimb were shipped to the National Museum of Natural History in Washington D.C., and a small section of tail vertebrae ended up in the Carnegie Museum in Pittsburgh. However, in 1929 Barnum Brown arranged for all of the material to be shipped to the American Museum of Natural History in New York City, where it remains today. A cast of this specimen (AMNH 6341) was controversially mounted in the lobby of the American Museum, rearing up to defend its young (AMNH 7530, now classified as *Kaatedocus siberi*) from an attacking *Allosaurus fragilis*.

More recently, more vertebrae and a pelvis were recovered in South Dakota. This material (SDSM 25210 and 25331) is stored in the collection of the South Dakota School of Mines and Technology in Rapid City.

Darren Naish has noted a common error in books of the late 20th century to depict *Barosaurus* as a kind of brachiosaur-like short tailed sauropod with raphes on its neck and body, and often curving the upper half of its neck downwards into a U-shape, citing it as an example of a Palaeoart meme. This originated with a drawing by Robert Bakker in a 1968 article, in which two *Barosaurus* appeared to have short tails due to a mix of foreshortening and one obscuring the other.

In 2007, paleontologist David Evans was flying to the U.S. Badlands when he discovered reference to a *Barosaurus* skeleton (ROM 3670) in the collection of the Royal Ontario Museum in Toronto, where he had recently become a curator. Earl Douglass had excavated this specimen at the Carnegie Quarry in the early 20th century; the ROM acquired it in a 1962 trade with the Carnegie Museum. The specimen was never exhibited and remained in storage until its rediscovery by David Evans 45 years later. He returned to Toronto and searched the storage areas and found many fragments, large and small, of the skeleton. It is now a centrepiece of the ROM's dinosaur exhibit, in the James and Louise Temerty Galleries of the Age of Dinosaurs. At almost 27.5 meters (90 feet) long, the specimen is the largest dinosaur ever to be mounted in Canada. The specimen is about 40% complete. As a skull of *Barosaurus* has never been found, the ROM specimen wears the head of a *Diplodocus.* Each bone is mounted on a separate armature so that it can be removed from the skeleton for study and then replaced without disturbing the rest of the skeleton. (See video "Dino Workshop" at reference.) In the rush to put the dinosaur on exhibit within ten weeks of its delivery to Research Casting International in 2500 pieces, not all of the skeletal fragments were mounted. In addition, more bones labeled ROM 3670 are still being found in storage. In future, more may be added to the specimen and it may turn out to be the most complete known.' (See video "Dino Assembly" at reference.) The ROM specimen is nicknamed "Gordo." John McIntosh believes that the ROM's skeleton is the same individual represented by four neck vertebrae labeled "CM 1198" in the collection of the Carnegie Museum.

### Discoveries in Africa

In 1907, German paleontologist Eberhard Fraas discovered the skeletons of two sauropods on an expedition to the Tendaguru Beds in German East Africa (now Tanzania). He classified both specimens in the new genus *Gigantosaurus*, with each skeleton representing a new species (*G. africanus* and *G. robustus*). However, this genus name had already been given to the fragmentary remains of a sauropod from England. Both species were moved to a new genus, *Tornieria*, in 1911. Upon further study of these remains and many other sauropod fossils from the hugely productive Tendaguru Beds, Werner Janensch moved the species once again, this time to the North American genus *Barosaurus*. In 1991, "Gigantosaurus" *robustus* was recognized as a titanosaur and placed in a new genus, *Janenschia*, as *J. robusta*. Meanwhile, many paleontologists suspected "Barosaurus" *africanus* was also distinct from the North American genus, which was confirmed when the material was redescribed in 2006. The African species, although closely related to *Barosaurus lentus* and *Diplodocus* from North America, is now once again known as *Tornieria africana*. A species of *Barosaurus* was also allegedly identified from the Kadsi Formation in Zimbabwe in 1987. However, this material is poorly preserved and fragmentary and was not adequately diagnosed as such, and so its referral to *Barosaurus* is doubtful. It may represent *Tornieria*.

## Paleobiology

### Feeding

The structure of the cervical vertebrae of *Barosaurus* allowed for a significant degree of lateral flexibility in the neck, but restricted vertical flexibility. This suggests a different feeding style for this genus when compared to other diplodocids. *Barosaurus* swept its neck in long arcs at ground level when feeding, which resembled the strategy that was first proposed by John Martin in 1987. The restriction in vertical flexibility suggests that *Barosaurus* did not primarily feed on vegetation that was high off the ground.

## Paleoecology

*Barosaurus* lived alongside numerous other Late Jurassic animals. *Barosaurus* would've shared its environment with similar Sauropods such as Diplodocus, *Apatosaurus*, *Camarasaurus*, *Brachiosaurus*, abd *Supersaurus*, as well as predatory dinosaurs such as *Allosaurus*, *Torvosaurus*, and *Ceratosaurus*. *Barosaurus* was one of the many Jurassic-dwelling animals that lived in the Morrison Formation, a giant formation of sedimentary stretching across numerous Western North American states.

## JPInstitute.com Description

Barosaurus was a very long member of the same family of dinosaurs that includes Diplodocus. It was a large, plant-eating, long-necked sauropod. It was one of the last of the longnecks that lived in North America during the Late Jurassic and possibly into the Early Cretaceous. They then disappeared in North America until the Late Cretaceous when these giant sauropods migrated up from South America.

Known primarily from one partial skeleton described in 1890 (re-described in 1919), and possibly a second species from Africa, Barosaurus is very similar to Diplodocus except for unusually long cervical (neck) vertebrae. The specimen was originally named Gigantosaurus based on its size. Its spectacularly long neck is showcased in a somewhat controversial pose in the rotunda of the American Museum of Natural History. The dinosaur is shown rearing up on its hind legs in a defensive posture with its head more than 30 feet in the air. Some paleontologists have stated that it would have been impossible for this dinosaur to stand like that.

## Appearance in other media

### *Jurassic Park*

In Jurassic World Though no living animals of this species make an appearance in the film, *Barosaurus* is mentioned on a sign depicting the map of Gyrosphere Valley.

## Links

http://web.archive.org/web/20030707040225/http://www.jpinstitute.com/dinopedia/dinocards/dc\_baros.html
https://web.archive.org/web/20080505072911/http://kids.yahoo.com/dinosaurs/82--Barosaurus

## References

1. ↑ 1.0 1.1 1.2 1.3 Template:Cite journal
2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Cite error: Invalid `<ref>` tag; no text was provided for refs named `mcintosh2005`
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Cite error: Invalid `<ref>` tag; no text was provided for refs named `upchurchetal2004`
4. ↑ 4.0 4.1 Template:Cite journal
5. ↑ Template:Cite journal
6. ↑ Template:Cite book
7. ↑ 7.0 7.1 7.2 Template:Cite journal
8. ↑ Template:Cite journal
9. ↑ Template:Cite journal
10. ↑ Template:Cite journal
11. ↑ Template:Cite journal
12. ↑ Template:Cite journal
13. ↑ Template:Cite journal
14. ↑ 14.0 14.1 Template:Cite journal
15. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `foster1996`
16. ↑ Template:Cite web
17. ↑ Template:Cite journal
18. ↑ Template:Cite press release
19. ↑ 19.0 19.1 Royal Ontario Museum. ROM Channel: Constructing the Barosaurus. Added 2012-08-28. Accessed 2012-12-11.
20. ↑ National Geographic, *Museum Secrets, Episode 3: Royal Ontario Museum*, Segment "Lost Dinosaur" Template:Webarchive. Broadcast December 10, 2012.
21. ↑ 21.0 21.1 National Geographic, *Museum Secrets, Episode 3: Royal Ontario Museum*, Segment "Lost Dinosaur". Video clips. Template:Webarchive. Broadcast December 10, 2012.
Template:Cite journal
Template:Cite book
24. ↑ Template:Cite journal
Template:Cite journal
Template:Cite journal
27. ↑ Template:Cite journal
28. ↑ Template:Cite journal
29. ↑ Template:Cite journal
30. ↑ Martin, John. 1987. Mobility and feeding of Cetiosaurus (Saurischia, Sauropoda) – why the long neck? pp. 154–159 in P. J. Currie and E. H. Koster (eds), Fourth Symposium on Mesozoic Terrestrial Ecosystems, Short Papers. Boxtree Books, Drumheller (Alberta). 239 pages.