Three boys - ages 7, 9 and 10 at the time - discovered a T. rex bone poking out of the ground while wandering through a fossil-rich stretch of North Dakota badlands, and an upcoming film this summer is going to feature their find.

The trio announced their discovery publicly on Monday during a Zoom news conference as workers at the Denver Museum of Nature and Science prepare to begin chipping the fossil out of its rock cast at a special exhibit called "Discovering Teen Rex." Two young brothers and their cousin said they were "completely speechless" when they made the rare find in July 2022.

The exhibit will open on June 21 and will coincide with the debut of the film "T.REX," which captures the young boys' paleontological journey. 

It all started when Kaiden Madsen joined his cousins, Liam and Jessin Fisher, on a hike through a stretch of land owned by the Bureau of Land Management around Marmarth, North Dakota. 

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Paleontologist with boys who discovered fossil

Vertebrate paleontologist Tyler Lyson, left, poses with young fossil finders Liam Fisher, Jessin Fisher and Kaiden Madsen on the day their expedition uncovered diagnostic features of a juvenile T. rex the boys discovered in the Badlands of North Dakota. (David Clark/Giant Screen Films via AP)

Jessin, a fan of Jurassic Park movies and an aspiring scientists advises other kids to "[j]ust put down their electronics and go out hiking," according to the Associated Press. 

Liam Fisher recalled that he and his dad, who accompanied the trio, first spotted the bone of the young carnivore. He said he thought the bone sticking out of the rock was something he described as "chunk-osaurus" — a made-up name for fragments of fossil too small to be identifiable.

The Tyrannosaurus rex is believed to have died around 67 million years ago. It was discovered in an area near Canada that at the time was similar to present-day Florida, with wildlife that included prehistoric turtles, fish, crocodiles and other cold-blooded species, according to the New York Post.

Sam Fisher took a photo of the discovery and showed it to a family friend, Tyler Lyson, who happened to be the associate curator of vertebrate paleontology at the Denver Museum of Nature and Science.

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Boys at dinosaur dig site

In this photo provided by Giant Screen Films, chief preparator Natalie Toth, left, of the Denver Museum of Nature and Science, examines fossilized plants from the Cretaceous period in a moment captured by the crew of the documentary "T.REX," at a fossil dig site in North Dakota, named "The Brothers." (Andy Wood/Giant Screen Films via AP)

Lyson first believed the find was a relatively common duckbill dinosaur. But he organized an excavation that began last summer, adding the boys and a sister, Emalynn Fisher, now 14, to the team.

It was when they unearthed a jaw bone that had multiple teeth along with it. 

They soon realized that their discovery was something more special. Lyson recalled that he started digging with Jessin where he thought he might find a neck bone.

"And it doesn’t get any more diagnostic than that, seeing these giant tyrannosaurus teeth starring back at you," Lyson said.

A Giant Screen Films documentary crew was on hand recording it.

"It was electric. You got goosebumps," Dave Clark, a member of the crew filming the documentary that later was narrated by Jurassic Park actor Sir Sam Neill, told the AP.

DIno dig boys courtesy of Giant Screen Films

Liam Fisher, Kaiden Madsen and Jessin Fisher pose for a celebratory photo on the day their fossil find was determined to be a juvenile T. rex, in North Dakota.  (David Clark/Giant Screen Films via AP)

Based on the size of the tibia, experts estimate the dino was 13 to 15 years old when it died and likely weighed around 3,500 pounds — about two-thirds of the size of a full-grown adult.

It is unclear yet how complete this fossil is. So far, a leg, a hip, a pelvis, a couple of tailbones and a good chunk of the skull have been found, Lyson said.

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"We wanted to share the preparation of this fossil with the public because it is a remarkable feeling," Lyson said. People will have about a year to watch crews chip away at the rock.  

The Associated Press contributed to this report.