In the lobby of the American Museum of Natural History is a cast of the sauropod dinosaur
Barosaurus, which is rearing up to defend its young from a carnivorous Allosaurus. A
second cast is present in the Natural History Museum of Utah and a genuine skeleton is on
display at the Royal Ontario Museum. Despite these exhibits, Barosaurus remains obscure
to the general public, and to most others is perceived as just a slightly different
version of the more famous Diplodocus with a longer neck. However, new fossil material
has shown that Barosaurus was an exceptional, record-breaking dinosaur. Not only was it
massive, but it may be the longest sauropod dinosaur known to science. Barosaurus is found
in the Morrison Formation in western North America, which was formed about 150 million
years ago during the Late Jurassic period. This is the same formation that includes household
names like Brontosaurus, Apatosaurus, Brachiosaurus, Diplodocus, Stegosaurus, Ceratosaurus, and
Allosaurus. Barosaurus was also once thought to have been present in Late Jurassic Africa,
though the fossils formerly assigned to Barosaurus there have since been given their own genus,
Tornieria. Like many of its more famous relatives and contemporaries, Barosaurus was first found
during the Bones Wars, a famous rivalry between the paleontologists Othniel Charles Marsh
and Edward Drinker Cope. The Barosaurus holotype was excavated by Marsh and his team in 1889
and named during the following year. A latter description of some Barosaurus fossils in
1899 was also the last scientific paper written by Marsh. While no complete Barosaurus skeleton
has been found, almost the entire skeleton besides the skull, feet, and the end of its
tail is accounted for. Barosaurus was a member of Diplodocidae, which also includes Brontosaurus,
Apatosaurus, Supersaurus, and, of course, Diplodocus. Diplodocids were relatively slender,
at least for sauropods, and possessed whip-like tails and necks that were long even by sauropods
standards. Diplodocid forelimbs were also short compared to other sauropods, although
Barosaurus’s forelimbs were longer than most other diplodocids. In most regards, Barosaurus
was very similar to Diplodocus, though Barosaurus’s neck was both longer and wider. Part of this
length was because Barosaurus had converted one of its dorsal vertebrae, into a sixteenth
cervical, or neck vertebra). But most of this extra length was because Barosaurus’s cervical
vertebrae were longer than those of Diplodocus, sometimes by as much as 50%. But most of this
extra length was because Barosaurus’s cervical vertebrae were longer than those of Diplodocus,
sometimes by as much as 50%. However, Barosaurus’s neural spines were shorter than those of Diplodocus,
perhaps to save weight for its longer neck. Its tail vertebrae were also shorter, resulting
in a proportionally shorter tail. But the most notable difference between the two was
Barosaurus’s sheer size. Barosaurus’s full name is Barosaurus lentus, which means
“slow heavy lizard”. This was a fitting name for an animal of its original estimated
size. The second largest specimen is about 27 meters long and had a weight between 15
to 20 metric tons, a decently sized sauropod on par with Diplodocus, but not exceptional.
However, while previously treated as not far off from Barosaurus’s true adult size, like
most sauropod specimens, this estimate was not based on a fully grown individual. The
largest Barosaurus specimen is a gigantic cervical vertebra which was previously misassigned
to Supersaurus. It is nearly a meter and a half long, longer than any other neck bone
ever found. Scaling this bone to other Barosaurus skeletons gives a length of 45 meters and
a weight of about 60 tons. This is truly exceptional, and these are conservative estimates. Such
a size dwarfs the previous estimates of Barosaurus’s size and is larger than any other known dinosaur
from the Morrison Formation, even Brachiosaurus and Supersaurus. It is also longer than any
other known sauropod dinosaur, and therefore any terrestrial tetrapod. With an estimated
neck length of 15 meters, it also had the longest neck of any of the “long necks”,
even longer than the neck of Mamenchisaurus. Not only that, but Barosaurus’s weight was
not that far off from the estimated weights of contenders for the title of heaviest sauropod,
such as Argentinosaurus and Patagotitan. Comparisons may at first make Barosaurus appear larger,
though Barosaurus probably wasn’t that much of a record-breaker. With its slender diplodocid
build, Barosaurus ultimately weighed less than these heavyweights. However, unlike the
other mega-sauropods, who are known from fairly limited remains, almost all of Barosaurus’s
skeleton is known, albeit from immature individuals. Of course, without a complete skeleton, it
is impossible to know for sure if the massive cervical vertebra is from Barosaurus lentus,
a new species of Barosaursus, or a new genus of sauropod closely related to Barosaursus.
Still, since all smaller Barosaurus fossils are from juveniles and Barosaurus lentus is
already fairly rare, it is likely the large specimen and the smaller ones are from the
same species. Either way, “heavy lizard” is an appropriate name for such a titanic
animal. That said, very few Barosaurus would actually reach their full adult size., Sauropods
laid numerous eggs, of which very few lived to reproduce. Even though sauropods grew fast,
it would still take a very long time to reach 60 tons, and without parental care, most would
be eaten by predators well before then. Therefore, while adult mortality was low, at any given
time there were a lot more Barosaurus alive who were the size of those on display at museums
than the much rarer, titanic adults. While its long neck may have been record breaking,
Barosaurus wasn’t able to move it very high. Though its neck was had good lateral flexibility,
it had reduced vertical flexibility compared to other sauropods. Its long neck is instead
thought to have allowed it to forage over a very wide area without having to move its
body. However, even if it couldn’t raise its neck very high, its sheer size would have
still allowed it to browse relatively high foliage. It is also speculated diplodocids
may have been able to rear up, greatly expanding their browsing options, though this remains
controversial. One factor that further complicates determining what Barosaurus ate is the lack
of a fossilized skull. Sauropod skulls are rare in general due to their solution of how
to deal with conflicting evolutionary pressure. They needed to reduce the weight of the skull
so it could be supported by their long necks. At the same time their heads still needed
to be large enough to support their senses and be able to ingest sufficient amounts of
food. To achieve this, sauropods skulls were made up of many hollow spaces and fragile
bones, which were not always tightly connected to each other. While effective in life, they
had poor perseveration potential in death. Without an actual skull of Barosaurus, it
is assumed it had one similar to other closely related diplodocids, which were relatively
low and elongated. They had peg-like teeth only found at the front of the jaws, which
were used for stripping leaves. While extinct, one Barosaurus had an interesting story happen
to it millions of years after its death. In 1962 the Royal Ontario Museum traded the skeletons
of two hadrosaurs with Carnegie Museum of Natural History in exchange for what they
thought was a Diplodocus skeleton, which was only later learned to belong to Barosaurus.
They hoped to add it to a refurbished exhibit but when it turned out there was not enough
space for it, the Barosaurus was left in storage where it would sit for years until it was
forgotten about. That changed in 2007. The Royal Ontario Museum was planning on making
a new dinosaur exhibit, and assigned associate curator Dr. David Evans to find a new sauropod
skeleton to be its centerpiece. While looking for options abroad, he came across a reference
to a sauropod skeleton already at the Royal Ontario Museum. When he returned, he found
the mostly complete Barosaurus, which wasn’t recorded in the database and had been split
up as isolated bones throughout the collection. Within eight weeks the skeleton was put on
display, with casts used to fill in the missing bones. It is now nicknamed Gordo, in honor
of Dr. Gordon Edmund, the curator who originally tried to have it displayed. Gordo is currently
the only Barosaurus skeleton on display in the world that contains the actual fossils
and is the largest mounted dinosaur skeleton in Canada. But at large as Gordo was, it died
long before it could reach even two thirds of its full length. Despite how exceptional
it is, few people know about Barosaurus, and even fewer are aware of just how massive it
was. Perhaps one day Barosaurus will be as popular as its more well-known cousins it
dwarfed. Thank you for watching. I hope you learned something interesting. Have a great
day, and, if you enjoyed the video, please remember to hit the like button.