Photo Credit: Glenn Storrs

A Dinosaur Tail: The incredible story of the world’s best Galeamopus fossil

How a Montana rancher, a Pennsylvania veterinarian, and a scientist from Cincinnati unearthed one of the best sauropod fossils ever found.

Next Generation Science Standards:

  • MS-ESS2-3. Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
  • MS-LS4-1. Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth under the assumption that natural laws operate today as in the past.

Key Vocabulary: fossil, resource partitioning, extinction, habitat, paleontologist, adaptation, species, environment, geologic era, geologic period

Galeamopus Article Guide


In the summer of 1999, a Montana rancher was walking across the high plains of the American West. He was a looking for dinosaur fossils, a passion of his ever since legendary paleontologist John Ostrom, one of the first proponents of the dinosaurs as birds theory, came to the area on a field study in the 1960s. The rancher was just a boy at the time, but like so many kids, dinosaurs had captured his imagination and he spent much of that summer working on Dr. Ostrom’s dig.

Decades later, the awe was still there. Every once in a while, the rancher would take a long hike around the land upon which his cattle grazed, prospecting for any trace of the long extinct dinosaurs. That day, the rancher eventually came across a stream where the water had eroded away part of a nearby hill. It was there, after tens of millions of years buried in rock, a small bit of fossilized bone lay exposed in the sunlight. The rancher knew he had found something, but what he didn’t know was that the fossil was a vertebrate from a nearly complete skeleton of a long-necked dinosaur named Galeamopus. 1500 miles away, Dr. Glenn Storrs sat in his office at the Cincinnati Museum Center Geier Collections Center, unaware that someone had just stumbled upon the biggest and most challenging discovery of his career.

Who was Galeamopus?

If you could hop into a time machine and travel to western North America 150 million years ago, it would look nothing like the rugged mountains and high plains we see today. Instead, you would see something more like the Amazon River Basin – a large, low lying area crossed by several river systems fed by mountains that would one day form the modern-day Rockies. There would be fish and crocodiles living in the wet areas, but no flowers, deciduous trees or even grasses as flowering plants had not yet evolved.

And of course, there would be dinosaurs. This area would one day be known as the Morrison Formation, a layer of rock that has preserved some of the best dinosaur fossils in the world. There would be Stegosaurus munching on nearby plants and small, raptor-like coelurosaurs scavenging for food. But the most obvious dinosaurs would be humongous, long-necked sauropods such as Galeamopus, moving in herds.

An artist’s rendition of the Jurassic world of Galeamopus. Photo Credit: Wikipedia/Gerhard Boeggemann

Around 27 meters long, Galeamopus a smaller member of the Diplodocus family of sauropods, the group of dinosaurs characterized by their slender necks and small heads. Sauropods dominated the Jurassic Period moving from one forested area to another, eating everything in sight to support their enormous bodies. These giants were able to flourish due to several unique environmental conditions. The weather in this part of the world at the time was hyper-seasonal, heavy monsoons, and flooding followed by extended periods of drought. This made food and water more likely to be concentrated with less hospitable areas in between. Big animals have a better chance of making the long treks across dry landscape from one resource-rich place to another.

The atmosphere was different – a lot more carbon dioxide was in the air made the planet much warmer. But perhaps most significantly, large size was a good defense against predators. The ferocious Allosaurus also roamed these lands, with serrated teeth that acted like carving knives and 6-inch claws that could slice through a prey’s flesh. Being big and moving in a group might be your best chance for survival.

One day in this lost world, a Galeamopus sat down in the mud of a riverbank, never to get up again, it’s body to be preserved in rock. That is until a curious Montana rancher and a resourceful paleontologist from Ohio came along to find it.

From Montana to Cincinnati

Glenn Storrs grew up in upstate New York and began looking around for fossils around his neighborhood as a kid. “Paleontologically, it’s a pretty boring place,” he says with a laugh. While the metaphoric bedrock of much of the Eastern US may be a bad place to find dinosaur fossils, the books Storrs’ father brought home from his work in the publishing business opened him up to an awesome prehistoric world. “There’s no better way to learn and let your imagination take you places than through reading.”

After getting a degree in geology and biology at nearby Syracuse, Storrs completed his Ph.D. at Yale under the advisory of the same John Ostrom whose fieldwork in Montana inspired the rancher who found the Galeamopus fossil. Eventually, he made his way to Cincinnati and became the Cincinnati Museum Center curator of vertebrate paleontology. But paleontology is a field in which you become more specialized as you go and Storrs was known for his work on ancient marine reptiles when the Galeamopus fossil was found. So how did a paleontologist in Ohio who knew less about long-necked dinosaurs that he did about long-necked plesiosaurs end up unearthing a sauropod fossil in Montana?

When the rancher first found the fossil, he called his brother-in-law, a veterinarian working at the University of Pennsylvania. Bringing a paleontology friend with him, the vet went out to survey the site. They began excavating the fossil but quickly realized that it belonged to a much bigger dinosaur than anyone had anticipated. After a few weeks, Storrs was contacted, who was working nearby on his own excavation project.

“By the time I got there, the UPenn people had already exposed a fair amount of it, says Storrs. “At that point, you could tell there was a lot of the skeleton left in the ground and it would be a major engineering project to get it out.”

Dr. Storrs working in the field. Photo Credit: Glenn Storrs

Dig, Dug

Finding a nearly complete fossilized skeleton is almost always the best day of a paleontologist’s career. An excited Glenn Storrs discussed the find with his friend and colleague Jack Horner, most famous for discovering dinosaurs took care of their young and who served as an inspiration for Sam Neill’s character in the original Jurassic Park film. Storrs recalls, “I spoke to Jack who said that once you’ve collected one sauropod fossil, you never want to collect another. Turns out he was right about that.”

Digging out a fossil the size of Galeamopus takes a lot of people, mostly volunteers and graduate students. This requires a high level of organization and logistics. Further complicating things is that bones aren’t always articulated, they are not in their natural positions. As the animal decomposed on an ancient stream bed millions of years ago, parts had started to wash downstream. “We found a shoulder blade next to the tail and found one of the limbs displaced by the tail,” says Dr. Storrs.  

So how do you dig a fossil weighing thousands of pounds out of the ground? The best way to start, Storrs explains, is to excavate the bones farthest away from the body as they are easiest to separate. Once a bone is removed, it’s covered in a field jacket – several layers of glue and toilet paper with a final layer of burlap soaked in plaster of Paris. However, larger bones like the femur or sections of the tail are far too heavy to move on their own and can present additional challenges. Removing them involves a technique called pedestalling, in which a trench is dug around the fossil then tunnels supported by 4×4’s are dug beneath, where the underlying rock is then carefully and perilously chiseled away. “It’s a great project for graduate students while I was able to give advice,” jokes Storrs.

Part of the Galeamopus fossil being excavated. Photo Credit: Glenn Storrs.

Though the fossil itself weighs about 3000 pounds, not all the rock can be removed off the fossil in the field – you’ve got to transport it back to the lab where they can be more precisely cleaned. The bones of the hips, ribs, and spine couldn’t be individually separated in the field. This meant it had to be not only taken out of the ground in one large chunk of rock, then driven to Cincinnati to fully excavate. Dr. Storrs recalls how a museum donor helped his team get a forklift to move the piece. “When we got on a truck scale to weight the block at the limestone quarry nearby, that piece alone weighted one and a half tons.”

For nearly two months each summer, Dr. Storrs and his team of students and volunteers dug out the Galeamopus fossil. At the end of each field season, a winter jacket of plaster of Paris was put on any exposed bone, topped with a tarp, then buried under a few feet of soil to protect the fossil from the harsh Montana winters. It took 6 years to get the entire skeleton was out of the ground. But the work was only just beginning. After bringing the Galeamopus fossil across the country, a pneumatic tool called an air scribe was used to remove the rest of the rock, grain by painstaking grain. This would take another 7 years and thousands of hours of work until the fossil was completely ready for the public to see.

A large piece of the Galeamopus fossil being loaded by forklift on a trailer to be taken back to Cincinnati. Photo Credit : Glenn Storrs

“You too can be a scientist”

With 85% of the skeleton intact, this fossil is potentially the best example of Galeamopus ever found and will be crucial to giving paleontologists a better understanding of it’s anatomy. More significantly, it will help researchers piece together the evolutionary tree of similar sauropods. It’s likely that many different sauropods lived alongside one another in the Late Jurassic, carefully partitioning resources. Understanding the differences in sauropod species could help paleontologists piece together the ancient ecosystem.

An entire exhibit on dinosaurs is on display at the Cincinnati Museum Center, featuring Galeamopus as well as the fossils of several other species. But while it’s easy to excite people about dinosaurs, not everyone can grow up and be a paleontologist. Which is why the Museum Center is focused on inspiring the next generation of scientists .“We’d like to try to get people to develop an appreciation for how science works.” Dr. Storrs says.  

Teaching children and adults alike to look at the world the way a scientist does is a big part of the Museum’s mission. By understanding how science works and its role in society helps people of all ages make decisions on the things that impact their lives. It’s more than just learning dates or how many bones are in a skeleton, it’s about encouraging people to make their own observations of the natural world. “You have to get out there, gather evidence, and come to sound conclusions that are testable. If you do that, then you too can be a scientist.”

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