How Wyoming's Brontosaurus Became The World's Most Famous Dinosaur — Twice

Brontosaurus, the long-necked “thunder lizard,” plodded across Wyoming over 150 million years ago. When the first massive skeleton of this sauropod was found near Medicine Bow in 1879, it immediately became one of the world’s most famous dinosaurs.

Ten years ago, Brontosaurus became one of the world’s most famous dinosaurs – again. It was "extinct" for 112 years until being unexpectedly resurrected in an intensive 2015 paper on the diversity of Late Jurassic sauropods.

No one was more surprised than Emanuel Tschopp, a sauropod expert and lead author of the 2015 paper. Dinosaur fans, who spent a century telling everyone that Brontosaurus technically wasn’t a valid dinosaur, rejoiced that the "thunder lizard" had come thundering back. 

“It felt weird and very exciting,” Tschopp told Cowboy State Daily. “I was bringing back an icon I myself had told everybody hadn’t actually existed.”

The War And The Thunder

To understand Brontosaurus's rise and fall and rise again, we have to go back in time. Although it went extinct at the end of the Late Jurassic Period, 146 million years ago, this sauropod saga truly started in the 1870s.

In 1877, self-financed paleontologist Othniel Charles Marsh from Yale University was studying the partial skeleton of a massive long-necked dinosaur found near Morrison, Colorado. Since he thought some of the bones resembled those from the marine reptile Mosasaurus, he named the new sauropod Apatosaurus, the “deceptive lizard.”

Two years later, a more complete skeleton of a massive sauropod was found in one of Marsh’s quarries at Como Bluff, the famous dinosaur ridge near Medicine Bow. Recognizing the grandeur of this discovery, and the publicity it would receive, Marsh named the specimen Brontosaurus excelsus, “the noble thunder lizard.”

Brontosaurus instantly entered the popular lexicon as one of the best-known dinosaurs, along with the other famous dinosaurs described by Marsh during the same period.

The underlying issue at the time was that Marsh was competing with Edward Drinker Cope, another self-financed paleontologist poking around Como Bluff, trying to find new dinosaurs. Their personal and professional rivalry became known as “the Bone Wars,” and Wyoming was the primary battlefield for this eccentric and destructive period in the infancy of American paleontology.

Marsh and Cope competed to excavate and publish new dinosaurs as quickly as possible. A handful of partial bones could be enough for either paleontologist to describe a new species, if only so they could usurp their rival in the newspapers and scientific journals.

The final tally of the Bone Wars was 53 new dinosaur species for Cope and 80 for Marsh. Many of their species are defunct today, mostly because their "new species" were either different specimens of the same dinosaur or the same dinosaur described (multiple times) by both paleontologists.

Neither man “won” the Bone Wars. Both Marsh and Cope died destitute and boneless as their vast fossil collections were either sold or seized from them, although many of Marsh’s dinosaurs have become top-tier prehistoric icons, including Brontosaurus, Stegosaurus and Triceratops.

Bye, Brontosaurus

Marsh and Cope were dead before the beginning of the 20th Century. With the influence of the pugnacious paleontologists no longer overshadowing the field, their peers, students, and haters started researching the post-collection carnage to see how well their science held up.

In 1903, paleontologist Elmer Riggs concluded that Marsh was overzealous in describing Brontosaurus and Apatosaurus as different dinosaurs. Both sauropods lived at the same place and time, the Late Jurassic in the American West, and their skeletons were extremely similar.

Riggs reckoned Brontosaurus and Apatosaurus weren’t different dinosaurs – they were different species of the same dinosaur. Because Apatosaurus was named two years before Brontosaurus, the first name became the official name for paleontologists to use.

Brontosaurus, already extinct, was defunct.

For the next 112 years, the world read books and gawked at museum displays that featured “Apatosaurus, formerly known as Brontosaurus.” Despite the scientific synonymizing making Apatosaurus the official name, it couldn’t escape the thunderous infamy of its better-known name, something the 70-foot, 20-ton sauropod shared with the 5-foot-2, 122-pound The Artist Formerly Known As Prince.

(Also, Brontosaurus was notorious for having the wrong head attached to the end of its long neck, but that’s an adjacent story of skullduggery for another time.)

Tschopp grew up learning that Brontosaurus was Apatosaurus. He never imagined that he’d become the sauropod expert to bring Brontosaurus back.

Thundering Back

By 2015, Tschopp was a Ph.D. paleontologist studying the diversity of Late Jurassic sauropods. He was studying diplodocids, the group of Late Jurassic sauropods that includes Diplodocus, Apatosaurus and Brontosaurus.

“I simply wanted to find out what species were in the collection of the Sauriermuseum Aathal museum in Switzerland, which were found near Shell in the Bighorn Basin,” he said. “To identify those Wyoming diplodocids, I needed to restudy the relationships in the entire group of diplodocids because none of the available systematic studies at that point had included all species of diplodocids.”

Tschopp built a computer database that analyzed over 500 skeletal traits of sauropod bones, then compared the consistency of those traits between dozens of specimens in museum collections in the United States and Europe.

“The software calculates how similar individual skeletons are and proposes a family tree based on these similarities,” he said.

As part of this intensive research, Tschopp examined the specimens Marsh studied to establish Apatosaurus and Brontosaurus. When their traits were analyzed and compared, they were similar, but different enough to be distinctly different.

“One of the most surprising results for myself was that the reference skeleton for Brontosaurus was, in fact, distinct enough from the reference skeleton of Apatosaurus to justify that these two were different genera.”

Not only was Brontosaurus back, but there were three distinct species: B. excelsus, B. parvus, and B. yahnahpin. Tschopp’s 2015 paper came like a thunderbolt out of the blue, and Brontosaurus regained its place as one of the most well-known and famous prehistoric animals.

How Are They Different

Even with the groundbreaking study showing they're different, Brontosaurus and Apatosaurus are still very similar dinosaurs in size, shape, and overall appearance. What are the differences between them?

“There is no easy way to tell the difference,” Tschopp said. “There is no single characteristic that would tell the two apart. It’s the number of different traits throughout the skeleton that makes them different.”

Tschopp used humans as a point of comparison. Even though we all outwardly look different from each other, our skeletons show that we’re all the same genus and species, Homo sapiens, and distinct from our closest extant relative, the chimpanzee.

The 2015 study concluded that the necks, shoulders, legs, and tails of Brontosaurus and Apatosaurus have several small but consistently different skeletal traits. That, Tschopp said, is enough to establish a consistent difference between the two massive sauropods.

“We don’t know how these differences would have translated to a distinct external appearance,” he said. “Most likely, there were even more differences in the soft tissues, but these are usually not preserved, so we simply have no clue about them.”

South Side Sauropods

Tschopp’s current research continues to delve into the diplodocid diversity of the Late Jurassic Period. One of the most intriguing patterns he’s examining is a distinct difference from north to south, with Wyoming right at the dividing line.

“The most interesting thing is that there seems to be an entirely different fauna preserved in the Morrison Formation of the Bighorn Basin and Montana compared to that of the classic localities in southern Wyoming, Colorado, and Utah,” he said.

Tschopp and his colleagues have described several new sauropods based on specimens from Thermopolis, Worland, Greybull, and Shell that were previously described as Brontosaurus, Apatosaurus, or Diplodocus. Northern Wyoming and Montana were the territories of Ardetosaurus, Galeamopus, Kaatedocus, and Suuwassea.

Meanwhile, Brontosaurus and Diplodocus seemed to stick to the south side of the Cowboy State and down in Colorado, Utah, and New Mexico.  Tschopp doesn’t have an explanation for this phenomenon (yet), but that’s what the science suggests.

“I have yet to see a bone from the Bighorn Basin that clearly belongs to the classic genera such as Diplodocus, Apatosaurus, or Brontosaurus,” he said. “I hope additional specimens and future excavations will help us understand that mystery.”

Here Today, Gone Tomorrow?

Brontosaurus has gone extinct, gone defunct, and returned to its former glory. The reaction to its decade-old resurrection was and has remained mixed and somewhat muted, which Tschopp expected when he published his paper.

“The resurrection of Brontosaurus was based on a single study, which has not yet been replicated,” he said. “I would say a majority of paleontologists have accepted our findings and are using Brontosaurus again in their publications, for now. Others are more conservative and keep using Apatosaurus.”

Tschopp indicated that ongoing and future studies could prove that his resurrection of Brontosaurus might have been erroneous. The second destruction of Brontosaurus could be by his own hand if that's what his research concludes.

“Everything in science can and should be a point of contention,” he said. “That’s how science works. Lots of other exciting and very nicely preserved specimens have been found and described since 2015, so I’m updating my database and rerunning my analyses. We’ll have to see how Brontosaurus holds up.”

Lifestyles Of The Big And Boney

Even with the resurrection of Brontosaurus, Tschopp said the “sample size” for this famous dinosaur is very low. All the known specimens of Brontosaurus have almost exclusively come from Wyoming.

“Most of the specimens that belong to the three species of Brontosaurus are from southern Wyoming, and one is from Utah,” he said. “From what we know, it’s not a widespread dinosaur.”

That’s why Tschopp is simultaneously exploring the world of Late Jurassic Wyoming. Asking questions about the landscapes and lifestyles of these increasingly distinct and diverse dinosaurs could reveal more about the exciting patterns turning up in Tschopp’s sauropod studies.

“I’ve been working a lot trying to understand how the ecosystem of the Morrison Formation worked,” he said. “How could all these enormous sauropods live there? Which species lived together? How did they avoid competition?”

Tschopp and his collaborators are examining sauropod teeth to understand their diets, using micro-CT scans to study the growth patterns preserved inside bones, and scrutinizing the rare pieces of soft tissue preservation to understand the physiology and anatomy of sauropods. These studies will eventually culminate in several scientific papers that could affirm or deny the legitimacy of Brontosaurus.

For now, Brontosaurus lives (in a relative sense). Tschopp is as confident now as he was 10 years ago when he unexpectedly resurrected the iconic dinosaur, and he’ll follow its thunderous footsteps wherever they lead.

“You have to follow your data in science, and that’s what it told me 10 years ago,” he said. “I have no clue yet what (our ongoing research) means for Brontosaurus. I guess we all have to stay tuned until we run our analyses.”

Andrew Rossi can be reached at arossi@cowboystatedaily.com.