Meet Supersaurus, the longest dinosaur in the world

The longest dinosaur that ever lived is the Supersaurus, new research reveals. According to Live Science, scientists have “fixed a fossil mix-up and analyzed new bones excavated from the long-necked dinosaur's final resting spot.”

Similar to other remarkably long dinosaurs, Supersaurus is what is called a diplodocid (meaning "double beams”) –– a long-necked sauropod with a very very long tail.

The fact that Supersaurus is the longest dinosaur that ever lived is a relatively new find, as it always had been one of the longest dinosaurs. But, research now shows that "this is the longest dinosaur based on a decent skeleton," as other dinosaur remains are fragmentary, and it's challenging to accurately estimate their lengths, Brian Curtice, a paleontologist at the Arizona Museum of Natural History who is spearheading the research, tells Live Science’s Laura Geggel.

Supersaurus roamed the Earth about 150 million years ago, during the Jurassic Period. According to Curtice’s new research, it exceeded 39 metres and possibly even reached 42 metres from snout to tail.

Live Science posits that even at 39 metres, Supersaurus would have been longer than another contender –– Diplodocus, which could reach lengths of 33 metres, according to a 2006 study of a specimen known as Seismosaurus in the New Mexico Museum of National History and Science Bulletin.

According to Live Science, the new research is not yet published in a peer-reviewed journal, but was presented online on November 5 at the Society of Vertebrate Paleontology's annual conference. 

The new finding is “nearly 50 years in the making; the first Supersaurus specimen was uncovered in 1972 in a chock-full bonebed; in what was basically a ‘bone salad,’ Curtice says. So, it wasn’t immediately clear which bones belonged to the beast.”

The person who worked on the ‘bone salad’ was field worker Jim Jensen, who collected and prepared fossils for Brigham Young University in Utah, in Dry Mesa Dinosaur Quarry in Colorado, Live Science explains.

“Jensen discovered an 8-foot-long (2.4 m) scapulocoracoid — two fused bones that make up the shoulder girdle in adult dinosaurs and other reptiles. The quarry also contained additional bones that Jensen thought belonged to two other sauropod dinosaurs, which years later he named Ultrasauros and Dystylosaurus.”

Jensen’s discovery was a popular one, with the public showing interest in a dinosaur longer than the then longest dinosaur Brachiosaurus, according to the blog Sauropod Vertebra Picture of the Week (SV-POW), run by paleontologists Michael Taylor and Mathew Wedel. Live Science says it was a journalist who incidentally named the biggest beast Supersaurus in the frenzy following its discovery.

Jensen published a study in the journal Great Basin Naturalist in 1985, telling the world of the three new sauropod discoveries from the quarry where the ‘bone salad’ had been. But because he wasn’t a trained paleontologist, some believe he erred in his identification of the bones.

Live Science reports that over the years, paleontologists debated whether Ultrasaurus and Dystylosaurus are valid genera, or whether – as Curtice believes– their bones were misidentified and actually all belong to a single Supersaurus.

Curtice makes the case for the three dinosaurs being actually just one Supersaurus in Live Science, pointing out the fit of the bones and the cracks apparent in them.

According to Curtice, previous Supersaurus length estimates placed it as one of the longest dinosaurs, including a 2008 estimate of 33 to 34 metres, but those were based on incomplete data, he says.

When the Dry Mesa Dinosaur Quarry was excavated, researchers wrapped large blocks of rocks and fossils in plaster jackets. According to Curtice, some still remain unopened today. He has started studying them and found five new neck vertebrae, one new back vertebra, two new tail vertebrae, and a left pubis.

Doing this helped him get “a more accurate estimate of the lengths for Supersaurus,” Laura Geggel for Live Science writes. “These newly identified bones helped Curtice get a more accurate estimate of the new lengths for Supersaurus, including that its neck was longer than 50 feet (15 m) and its tail was upward of 60 feet (18 m) long.”

What's more, the size and shape of the newly identified bones support the idea that all of the colossal bones found at Dry Mesa belong to Supersaurus, rather than three different large dinosaurs, Curtice says.

Once his as-yet-unpublished paper goes through peer review, Curtice’s findings will resonate more, a colleague suggests. 

"I think the final verdict will come when this Goliath specimen [that Curtice is using to inform his analysis] is published, when this additional material from Dry Mesa is published. I want to see it go through formal peer review," Matt Lamanna, a vertebrate paleontologist at the Carnegie Museum of Natural History in Pittsburgh, who was not involved with the research, tells Live Science.

"I think it will be pretty exciting when he does," Lamanna adds. "I think he's very probably correct."