Barosaurus
Encyclopedia
Barosaurus icon ; Greek
barys/βαρυς meaning 'heavy' and saurus/σαυρος meaning 'lizard', 'heavy lizard
') was a giant, long-tailed, long-necked, plant-eating
dinosaur
closely related to the more familiar Diplodocus
. Remains have been found in the Morrison Formation
from the Upper Jurassic
Period, along with five other sauropods: Diplodocus
, Apatosaurus
, Camarasaurus
, Brachiosaurus
and Haplocanthosaurus
, as well as the predator Allosaurus
and armored
dinosaur Stegosaurus
. It is present in stratigraphic zones 2-5.
Barosaurus was an enormous animal, with some adults measuring more than 26 meters (86 feet) in length and weighing more than 20 metric tons (22 short ton
s). 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).
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 more slender builds and longer necks and tails than apatosaurines, the other subfamily of diplodocids.
The systematics
(evolution
ary 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 species 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
.
The first Barosaurus remains were discovered in the Morrison Formation
of South Dakota
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/barus ("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 landowners until it was collected nine years later, in 1898, by Marsh's assistant, George Wieland. Marsh described these new remains, consisting of vertebrae, ribs and limb bones, and classified Barosaurus 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, B. 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 what is now known as Dinosaur National Monument
. Four neck vertebrae, each one 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 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 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 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. 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 from a marauding Allosaurus.
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
. In 2007, paleontologist David Evans discovered a partial Barosaurus skeleton forgotten in the collection of the Royal Ontario Museum
in Toronto
, where he had recently become a curator
. Earl Douglass excavated this specimen (ROM
3670) at the Carnegie Quarry in the early 20th century and the ROM acquired it in a 1962 trade with the Carnegie Museum. The specimen never made it out on exhibit and instead remained in storage until its rediscovery 45 years later. It is now one of the centerpieces of the dinosaur exhibit at the ROM. John McIntosh believes that this skeleton is the same individual represented by four neck vertebrae (CM 1198) in the collection of the Carnegie Museum.
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.
, which is widespread in the western United States between the Great Plains
and Rocky Mountains
. Radiometric dating
agrees with biostratigraphic
and paleomagnetic
studies, indicating that the Morrison was deposited during the Kimmeridgian
and early Tithonian
stages of the Late Jurassic
Period, or approximately 155 to 148 million years ago. Barosaurus fossils are found in late Kimmeridgian sediments, around 150 million years old.
The Morrison Formation was deposited in floodplain
s along the edge of the ancient Sundance Sea
, an arm of the Arctic Ocean
which extended southward to cover the middle of North America as far south as the modern state of Colorado
. Due to tectonic uplift
to the west, the sea was receding to the north, and had retreated into what is now Canada
by the time Barosaurus evolved. The sediments of the Morrison were washed down out of the western highlands, which had been uplifted during the earlier Nevadan orogeny
and were now eroding. Very high atmospheric concentrations of carbon dioxide
in the Late Jurassic led to high temperatures around the globe, due to the greenhouse effect
. One study, estimating CO2 concentrations of 1120 parts per million, predicted average winter temperatures in western North America of 20 °C (68 °F) and summer temperatures averaging 40–45 °C (104–113 F). A more recent study suggested even higher CO2 concentrations of up to 3180 parts per million. Warm temperatures that led to significant evaporation
year-round, along with possible rain shadow
effect from the mountains to the west, led to a semi-arid climate with only seasonal rainfall.
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
barys/βαρυς meaning 'heavy' and saurus/σαυρος meaning 'lizard', 'heavy lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
') was a giant, long-tailed, long-necked, plant-eating
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
closely related to the more familiar Diplodocus
Diplodocus
Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones...
. Remains have been found in the Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
from the Upper Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
Period, along with five other sauropods: Diplodocus
Diplodocus
Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones...
, Apatosaurus
Apatosaurus
Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...
, Camarasaurus
Camarasaurus
Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...
, Brachiosaurus
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...
and Haplocanthosaurus
Haplocanthosaurus
Haplocanthosaurus is a genus of sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period , 155 to 152 million years ago. The type species is H. priscus, and the referred species H...
, as well as the predator Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
and armored
Armour (zoology)
Armour in animals is external or superficial protection against attack by predators, formed as part of the body , usually through the hardening of body tissues, outgrowths or secretions. It has therefore mostly developed in 'prey' species...
dinosaur Stegosaurus
Stegosaurus
Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well...
. It is present in stratigraphic zones 2-5.
Description
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...
s). 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
Spinous process
The spinous process of a vertebra is directed backward and downward from the junction of the laminae , and serves for the attachment of muscles and ligaments. In animals without an erect stance, the process points upward and may slant forward or backward...
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
Chevron (anatomy)
A chevron is one of a series of bones on the ventral side of the tail in many reptiles, dinosaurs , and some mammals such as kangaroos and manatees....
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
Digitigrade
A digitigrade is an animal that stands or walks on its digits, or toes. Digitigrades include walking birds , cats, dogs, and many other mammals, but not plantigrades or unguligrades...
, 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
Pes (zoology)
The pes is the zoological term for the distal portion of the hind limb of tetrapod animals. It is the part of the pentadactyl limb that includes the metatarsals and digits . During evolution, it has taken many forms and served a variety of functions...
(hindfoot).
Classification and systematics
Barosaurus is a member of the sauropod familyFamily (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
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 more slender builds and longer necks and tails than apatosaurines, the other subfamily of diplodocids.
The systematics
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
(evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary 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 species 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
Australodocus
Australodocus, meaning "southern beam" from the Latin australis "southern" and the Greek dokos/δοκоς "beam", is a sauropod dinosaur that lived during the Late Jurassic period, around 150 million years ago in what was then German East Africa...
from the famous Tendaguru Beds
Tendaguru
The Tendaguru Beds are a fossil-rich formation in Tanzania. It has been considered the richest of Late Jurassic strata in Africa. Continental reconstructions show Tendaguru to have been in the southern hemisphere during the Late Jurassic. Tendaguru is similar to the Morrison Formation except in...
of Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
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
Supersaurus
Supersaurus is a genus of diplodocid sauropod dinosaur discovered by Vivian Jones of Delta, Colorado, in the Upper Jurassic Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating to about 153 million years ago...
. The early genus Suuwassea
Suuwassea
Suuwassea is a genus of diplodocoid sauropod dinosaur found in the Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, USA. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000, described by J.D....
is considered by some to be an apatosaurine, while others regard it as a basal member of the superfamily
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
Diplodocoidea
Diplodocoidea
Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias...
. Diplodocid fossils are found in North America, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, and Africa. More distantly related within Diplodocoidea are the families Dicraeosauridae
Dicraeosauridae
Dicraeosauridae is a family of sauropod dinosaurs known from the Late Jurassic and Early Cretaceous of Africa and South America. Currently only three genera are recognised; the Jurassic South American genus Brachytrachelopan, the Jurassic African Dicraeosaurus and the South American Early...
and Rebbachisauridae
Rebbachisauridae
Rebbachisauridae is a family of sauropod dinosaurs known from fragmentary fossil remains from the Cretaceous of South America, Africa, and Europe.-Taxonomy:...
, found only on the southern continents
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
.
Discovery and naming
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
of South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
by Othniel Charles Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
and John Bell Hatcher
John Bell Hatcher
John Bell Hatcher was an American paleontologist and fossil hunter best known for discovering Torosaurus.-Biography:...
of Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
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/barus ("heavy") and σαυρος/sauros ("lizard"), and the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word lentus ("slow"). The rest of the type specimen was left in the ground under the protection of the landowners until it was collected nine years later, in 1898, by Marsh's assistant, George Wieland. Marsh described these new remains, consisting of vertebrae, ribs and limb bones, and classified Barosaurus 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, B. 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
Carnegie Museum of Natural History
Carnegie Museum of Natural History, located at 4400 Forbes Avenue in the Oakland neighborhood of Pittsburgh, Pennsylvania, USA, was founded by the Pittsburgh-based industrialist Andrew Carnegie in 1896...
sent fossil hunter Earl Douglass to Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
to excavate the Carnegie Quarry in what is now known as Dinosaur National Monument
Dinosaur National Monument
Dinosaur National Monument is a National Monument located on the southeast flank of the Uinta Mountains on the border between Colorado and Utah at the confluence of the Green and Yampa Rivers. Although most of the monument area is in Moffat County, Colorado, the Dinosaur Quarry is located in Utah...
. Four neck vertebrae, each one meter (3 feet) long, were collected in 1912 near a specimen of Diplodocus, but a few years later, William Jacob Holland
William Jacob Holland
William Jacob Holland was the eighth Chancellor of the University of Pittsburgh and Director of the Carnegie Museums of Pittsburgh. He was an accomplished zoologist and paleontologist, as well as an ordained Presbyterian minister.-Life:Holland was born August 16, 1848 in Jamaica, West Indies, the...
realized they belonged to a different species. Meanwhile, the type specimen of Barosaurus had finally been prepared at Yale and was fully described by Richard Swann Lull in 1919. Based on Lull's description, Holland referred the vertebrae (CM
Carnegie Museum of Natural History
Carnegie Museum of Natural History, located at 4400 Forbes Avenue in the Oakland neighborhood of Pittsburgh, Pennsylvania, USA, was founded by the Pittsburgh-based industrialist Andrew Carnegie in 1896...
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 was excavated from the Carnegie Quarry in 1923 by Douglass, now working for the University of Utah
University of Utah
The University of Utah, also known as the U or the U of U, is a public, coeducational research university in Salt Lake City, Utah, United States. The university was established in 1850 as the University of Deseret by the General Assembly of the provisional State of Deseret, making it Utah's oldest...
after the death of U.S. Steel
U.S. Steel
The United States Steel Corporation , more commonly known as U.S. Steel, is an integrated steel producer with major production operations in the United States, Canada, and Central Europe. The company is the world's tenth largest steel producer ranked by sales...
founder Andrew Carnegie
Andrew Carnegie
Andrew Carnegie was a Scottish-American industrialist, businessman, and entrepreneur who led the enormous expansion of the American steel industry in the late 19th century...
, who had been financing Douglass' earlier work in Pittsburgh. Material from this specimen was 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
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. Admission is free and the museum is open 364 days a year....
in Washington D.C., and a small section of tail vertebrae ended up in the Carnegie Museum in Pittsburgh. In 1929, Barnum Brown
Barnum Brown
Barnum Brown , a paleontologist born in Carbondale, Kansas, and named after the circus showman P.T. Barnum, discovered the second fossil of Tyrannosaurus rex during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century.Sponsored...
arranged for all of the material to be shipped to the American Museum of Natural History
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
in New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
, where it remains today. A cast
Casting
In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...
of this specimen (AMNH
American Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
6341) was controversially mounted in the lobby of the American Museum, rearing up to defend its young from a marauding Allosaurus.
More recently, more vertebrae and a pelvis were recovered in South Dakota. This material (SDSM
South Dakota School of Mines and Technology
The South Dakota School of Mines and Technology is a public institution of higher learning in Rapid City, South Dakota governed by the South Dakota Board of Regents. Founded in 1885 as the Dakota School of Mines, Tech offers degree programs in engineering and science fields. 2,354 students were...
25210 and 25331) is stored in the collection of the South Dakota School of Mines and Technology
South Dakota School of Mines and Technology
The South Dakota School of Mines and Technology is a public institution of higher learning in Rapid City, South Dakota governed by the South Dakota Board of Regents. Founded in 1885 as the Dakota School of Mines, Tech offers degree programs in engineering and science fields. 2,354 students were...
in Rapid City
Rapid City, South Dakota
Rapid City is the second-largest city in the U.S. state of South Dakota, and the county seat of Pennington County. Named after Rapid Creek on which the city is established, it is set against the eastern slope of the Black Hills mountain range. The population was 67,956 as of the 2010 Census. Rapid...
. In 2007, paleontologist David Evans discovered a partial Barosaurus skeleton forgotten in the collection of the Royal Ontario Museum
Royal Ontario Museum
The Royal Ontario Museum is a museum of world culture and natural history in Toronto, Ontario, Canada. With its main entrance facing Bloor Street in Downtown Toronto, the museum is situated north of Queen's Park and east of Philosopher's Walk in the University of Toronto...
in Toronto
Toronto
Toronto is the provincial capital of Ontario and the largest city in Canada. It is located in Southern Ontario on the northwestern shore of Lake Ontario. A relatively modern city, Toronto's history dates back to the late-18th century, when its land was first purchased by the British monarchy from...
, where he had recently become a curator
Curator
A curator is a manager or overseer. Traditionally, a curator or keeper of a cultural heritage institution is a content specialist responsible for an institution's collections and involved with the interpretation of heritage material...
. Earl Douglass excavated this specimen (ROM
Royal Ontario Museum
The Royal Ontario Museum is a museum of world culture and natural history in Toronto, Ontario, Canada. With its main entrance facing Bloor Street in Downtown Toronto, the museum is situated north of Queen's Park and east of Philosopher's Walk in the University of Toronto...
3670) at the Carnegie Quarry in the early 20th century and the ROM acquired it in a 1962 trade with the Carnegie Museum. The specimen never made it out on exhibit and instead remained in storage until its rediscovery 45 years later. It is now one of the centerpieces of the dinosaur exhibit at the ROM. John McIntosh believes that this skeleton is the same individual represented by four neck vertebrae (CM 1198) in the collection of the Carnegie Museum.
Discoveries in Africa
In 1907, GermanGermans
The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....
paleontologist Eberhard Fraas
Eberhard Fraas
Eberhard Fraas was a German geologist and paleontologist. He worked as a curator at the Stuttgarter Naturaliensammlung and discovered the dinosaurs of the Tendaguru formation in then German East Africa ....
discovered the skeletons of two sauropods on an expedition to the Tendaguru Beds in German East Africa
German East Africa
German East Africa was a German colony in East Africa, which included what are now :Burundi, :Rwanda and Tanganyika . Its area was , nearly three times the size of Germany today....
(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
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. 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
Werner Janensch
Werner Ernst Martin Janensch was a German paleontologist and geologist.Janensch's most famous contributions stemmed from the expedition he led with Edwin Hennig to the Tendaguru Beds in what is now Tanzania...
moved the species once again, this time to the North American genus Barosaurus. In 1991, "Gigantosaurus" robustus was recognized as a titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
and placed in a new genus, Janenschia
Janenschia
Janenschia was a large sauropod from Late Jurassic Africa , and therefore the earliest known titanosaur. Originally thought to be a species of the diplodocid Tornieria/Barosaurus , it was later found to be a distantly related titanosaur. So far, it is only known from Tanzania...
, 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.
Paleoecology
Barosaurus remains are limited to the Morrison FormationMorrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
, which is widespread in the western United States between the Great Plains
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...
and Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
. Radiometric dating
Radiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
agrees with biostratigraphic
Biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. Usually the aim is correlation, demonstrating that a particular horizon in one geological section represents the same period...
and paleomagnetic
Paleomagnetism
Paleomagnetism is the study of the record of the Earth's magnetic field in rocks. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form. This record provides information on the past behavior of Earth's magnetic field and the past location of...
studies, indicating that the Morrison was deposited during the Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
and early Tithonian
Tithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
stages of the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
Period, or approximately 155 to 148 million years ago. Barosaurus fossils are found in late Kimmeridgian sediments, around 150 million years old.
The Morrison Formation was deposited in floodplain
Floodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...
s along the edge of the ancient Sundance Sea
Sundance Sea
The Sundance Sea was an epeiric sea that existed in North America during the mid to late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western United States...
, an arm of the Arctic Ocean
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
which extended southward to cover the middle of North America as far south as the modern state of Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
. Due to tectonic uplift
Tectonic uplift
Tectonic uplift is a geological process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation. Uplift may be orogenic or isostatic.-Orogenic uplift:...
to the west, the sea was receding to the north, and had retreated into what is now Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
by the time Barosaurus evolved. The sediments of the Morrison were washed down out of the western highlands, which had been uplifted during the earlier Nevadan orogeny
Nevadan orogeny
The Nevadan Orogeny was a major mountain building event that took place along the western edge of ancient North America between the Mid to Late Jurassic...
and were now eroding. Very high atmospheric concentrations of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the Late Jurassic led to high temperatures around the globe, due to the greenhouse effect
Greenhouse effect
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...
. One study, estimating CO2 concentrations of 1120 parts per million, predicted average winter temperatures in western North America of 20 °C (68 °F) and summer temperatures averaging 40–45 °C (104–113 F). A more recent study suggested even higher CO2 concentrations of up to 3180 parts per million. Warm temperatures that led to significant evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
year-round, along with possible rain shadow
Rain shadow
A rain shadow is a dry area on the lee side of a mountainous area. The mountains block the passage of rain-producing weather systems, casting a "shadow" of dryness behind them. As shown by the diagram to the right, the warm moist air is "pulled" by the prevailing winds over a mountain...
effect from the mountains to the west, led to a semi-arid climate with only seasonal rainfall.