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A father, his two sons and their cousin were hiking in the Badlands of North Dakota in 2022 when they found what looked like a dinosaur leg sticking out of a rock.
Sam Fisher, his sons Jessin and Liam, then 10 and 7, and their cousin Kaiden Madsen, who was 9, had been amateur fossil hunters for years and knew the area – the Hell Creek Formation – was rich in it because they had admitted some of the most famous Tyrannosaurus rex skeletons in the world.
However, little did they know that they were making an important scientific discovery.
“My dad yelled for Jessin and Kaiden to come, and they came running,” Liam said during a press conference in Denver on Tuesday. “Dad asked, ‘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 curator at the Denver Museum of Nature & Science, Dr. Tyler Lyson, who had been a classmate of his in high school.
Now the museum has unveiled what it calls ‘Teen Rex’, a rare juvenile T. rex skeleton, one of only a few in existence. The public can see it being removed from the rock during the opening of the exhibition on June 21.
‘Wishful thoughts’
When he first got the photo 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. “Later I looked at the photos more closely. And the way the bone broke down into sheets indicated that it may have been a carnivorous dinosaur.”
He then texted his paleontology friends 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 wishful thinking.”
Nevertheless, Lyson set up an excavation in July 2023, bringing along the family of discoverers. “The kids were with us every step of the way, which was great,” he said. “On the first day we realized it was a T. rex. There were cameras rolling as it happened.”
Lyson hoped to find a neck bone, which would have helped distinguish between a duck-billed dinosaur and a T. rex, as these are different in the two species. Instead, he got something much better: “We uncovered a lower jaw with a number of teeth sticking out of it,” which he said was undeniable evidence that the fossil was a T. rex.
“I was completely speechless,” Jessin Fisher said of the moment he realized the fossil was in fact a T. rex.
They then proceeded to remove the overlying rock and over the course of eleven days they carefully excavated the 66-million-year-old sandstone rock layer that contained the fossil, which they collected in a 3-meter-long and 1.5-meter-wide enclosure. plaster jacket weighing more than 6,000 pounds.
It was too heavy to be lifted by a regular helicopter, so a more advanced Black Hawk was called in. Less than a year later, the piece is about to become a live museum exhibit, where visitors can watch scientists clean up the fossil. and separating the individual bones — a process that can take up to a year, Lyson said.
The exhibition will also screen a 40-minute documentary entitled “T-REX”; it includes behind-the-scenes footage of the fossil’s excavation.
Juvenile T. Rex thinks: a heated debate
Based on early estimates, Lyson thinks the fossil is that of 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. According to Lyson, an adult T. rex averaged 40 feet in length and weighed at least 8,000 pounds.
The skeleton is about 30% complete, but Lyson said the bones are in good condition.
“We know we have an articulated leg with the hip bones, we have some tail vertebrae and I think quite a bit of the skull. We hope there’s a lot more of the skeleton in the rock, but it’s weird that we have no ribs, no arms, not many vertebrae – that could very well be the case. There may be more of it where this came from,” he said, adding that he is making plans to go back to the Hell Creek Formation and excavate more.
Juvenile dinosaur fossils are rare because they are smaller and therefore harder to find, and more amenable to consumption after death because of their softer bones, Lyson said. Once the researchers isolate a bone, they can carefully analyze it and gain more information about the fossil, perhaps confirming whether it is a juvenile T. rex or something else.
That distinction is currently a hotly debated topic in paleontology, and a paper published this year argued that some of the few juvenile T. rex skeletons found could belong to a separate species called Nanotyrannus.
“That’s been a hotly contested debate, the Nanotyrannus versus Tyrannosaurus Rex,” Lyson said. “I still think ours is a juvenile because it’s too big to be a Nanotyrannus. There are other things that indicate it is also a juvenile, in terms of skeletal maturity. This copy will undoubtedly weigh heavily on that debate. It will be a new data point on which people can base their arguments, and that is important.”
Once the bone studies are completed, Lyson will work on a scientific study outlining the discovery, which he plans to publish within the next few years.
Nick Longrich, a paleontologist and evolutionary biologist at the University of Bath in the United Kingdom and one of the authors of the Nanotyrannus paper, said confirming a find of a young T. rex would be extraordinary. “Tyrannosaurus is not common and young dinosaurs are incredibly rare, so young T. rex are the rarest of the rare,” he said.
“For that reason I am sceptical. So far, almost all ‘juvenile T. rex’ are adults of its smaller cousin, Nanotyrannus. Since I don’t know anything else about it, I would be inclined to assume that they have,” Longrich added. “But if they finally get a good skeleton of a little T. rex, that would be pretty remarkable, and amazing to see – it’s kind of the holy grail of Hell Creek dinosaur fossils. But sooner or later a good skeleton of a young T. rex will turn up. I am curious about the newspaper.”
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