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A father, his two sons and their cousin were hiking in Badlands, North Dakota in 2022 when they found what appeared to be a dinosaur leg sticking out of a rock.
Sam Fisher, his children, Jessin and Liam, then ages 10 and 7, and their cousin Kaiden Madsen, age 9, had been amateur fossil hunters for years and knew that the area – the Hell Creek Formation – was rich in them, having rendered some of the most famous Tyrannosaurus rex skeletons in the world.
They did not know, however, that they were making a significant scientific discovery.
“My dad yelled for Jessin and Kaiden to come, and they came running,” Liam said during a press conference Tuesday in Denver. “Dad said, ‘What is this?’ And Jessin said, ‘That’s a dinosaur!’”
They posed for a photo with the bones, and Fisher sent the image to paleontologist and Denver Museum of Nature and Science curator Dr. Tyler Lyson, who was his high school classmate.
Now, the museum has revealed what it calls “Teen Rex”, a rare juvenile T. rex skeleton, one of the few in existence. The public will be able to see it extracted from the rock in the exhibition that will open on June 21st.
‘Positive thinking’
When he first saw the image of the leg bone, Lyson thought he was looking at a duck-billed dinosaur.
“I didn’t know it was a T. rex, because all I had were pictures, and the knee joint looked like a duck’s bill,” he said. “Then I started looking at the photos a little more closely. And the way the bone broke into layers indicated that it could be a carnivorous dinosaur.”
He then messaged his paleontologist friends, checking to see if anyone thought it might be a T. rex. “They said, ‘No, it looks like a duckbill.’ And I thought, OK, probably just an illusion.
Even so, Lyson began an excavation in July 2023, bringing his family of discoverers with him. “The kids were with us every step of the way, which was great,” he said. “We realized it was a T. rex on the first day. We had cameras filming while this was happening.”
Lyson hoped to find a neck bone, which would have helped distinguish between a duck-billed dinosaur or a T. rex, as the two species are different. Instead, he got something much better: “We discovered a lower jaw with a bunch of teeth sticking out,” which he believes is unequivocal proof that the fossil was a T. rex.
“I was completely speechless,” Jessin Fisher said of the moment she realized the fossil was actually a T. rex.
They then removed the underlying rock and, over the course of 11 days, carefully unearthed the 66-million-year-old sandstone rock layer that contained the fossil, which they collected in a 9-foot-long, 5-foot-wide pit. width. plaster jacket weighing over 6,000 pounds.
It was too heavy to be lifted by a normal helicopter, so a more advanced Black Hawk was called in. Less than a year later, the piece is about to become a living museum exhibit, during which visitors will be able to watch scientists clean the fossil. and separate individual bones — a process that can take up to a year, Lyson said.
A 40-minute documentary titled “T-REX,” will also be presented at the exhibition; includes behind-the-scenes footage of the fossil excavation.
Juvenile T. Rex discoveries: a fierce debate
Based on early estimates, Lyson thinks the fossil is from a young T. rex that died of an unknown cause when it was 13 or 15 years old. It was about 25 feet long and weighed about 3,500 pounds. An adult T. rex averaged 40 feet long and weighed at least 8,000 pounds, according to Lyson.
The skeleton is about 30 percent complete, but Lyson said the bones are in good condition.
“We know we have a jointed leg with hip bones, we have some tail vertebrae and I think a decent chunk of skull. We hope there’s a lot more skeleton inside the rock, but it’s strange that we don’t have any ribs, we don’t have any arms, we don’t have a lot of vertebrae – well there could maybe be more where that came from,” he said, adding that he is making plans to return to the rock. Hell Creek Formation and excavate further.
Juvenile dinosaur fossils are rare because they are smaller and therefore harder to find, and more likely to be consumed after death due to their softer bones, Lyson said. Once researchers isolate a bone, they can analyze it carefully and gain more information about the fossil, and perhaps confirm whether it is a juvenile T. rex or something else.
This distinction is a hot topic in paleontology right now, and a paper published this year argued that some of the few juvenile T. rex skeletons found may belong to a separate species called Nanotyrant.
“This has been a fierce debate, Nanotyrannus versus Tyrannosaurus Rex,” Lyson said. “I still think ours is juvenile, because it’s too big to be a Nanotyrannus. There are other things that suggest he is also a young man, in terms of skeletal maturity. Without a doubt, this copy will have great weight in this debate. It will be another data point from which people can make their arguments, and that’s important.”
Once the bone scans are complete, Lyson will work on a scientific study describing the discovery, which he plans to publish in the coming years.
Nick Longrich, paleontologist and evolutionary biologist at the University of Bath, UK, and one of the authors of Nanotyrannus paper, said confirming the discovery of a juvenile T. rex would be extraordinary. “Tyrannosaurus is not common and juvenile dinosaurs are incredibly rare, so young T. rex are the rarest of the rare,” he said.
“For that reason I am skeptical. So far, almost all “T. rex juveniles” are actually adults of their smaller cousin, Nanotyrannus. Not knowing anything else about it, I tend to guess that’s what they have,” Longrich added. “But if they finally have a good skeleton of a small T. rex, that would be quite remarkable and great to see – it’s kind of the Holy Grail of Hell Creek dinosaur fossils. But a good skeleton of a young T. rex should turn up sooner or later. I will be interested in seeing the newspaper.
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