Reconstruction of the ancient 67 million-year-old landscape of North Dakota with a juvenile Tyrannosaurus rex (Teen Rex). Credit: Andrey Atuchin (artist) and Denver Museum of Nature & Science.

Two young brothers and their cousin were wandering through a fossil-rich stretch of the North Dakota badlands when they made a discovery that left them "completely speechless": a T. rex bone poking out of the ground.

The trio announced their discovery publicly Monday at a Zoom news conference as workers at the Denver Museum of Nature & Science prepare to begin chipping the fossil out of its rock cast at a special exhibit called Discovering Teen Rex. The exhibit's opening on June 21 will coincide with the debut of the film "T.REX," about the July 2022 find.

It all started when Kaiden Madsen, then 9, joined his cousins, Liam and Jessin Fisher, then 7 and 10, on a hike through a stretch of land owned by the Bureau of Land Management around Marmarth, North Dakota. Hiking is a favorite pastime of the brothers' father, Sam Fisher.

"You just never know what you are going to find out there. You see all kinds of cool rocks and plants and wildlife," he said.

Liam Fisher recalled that he and his dad, who accompanied the trio, first spotted the bone of the young carnivore. After its death around 67 million years ago, it was entombed in the Hell Creek Formation, a popular paleontology playground that spans Montana, Wyoming and the Dakotas. The formation has yielded some of the most well-preserved T. rex fossils ever. Among them is Sue, a popular attraction at the Field Museum in Chicago, and Wyrex, a star at the Houston Museum of Natural Science.

In this photo provided by Giant Screen Films, Jessin Fisher digs for fossils on public lands near his home in Marmath, N.D. Credit: Sam Fisher/Giant Screen Films via AP

But none of them knew that then. Liam 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.

Still, Sam Fisher snapped a picture and shared it with a family friend, Tyler Lyson, the associate curator of vertebrate paleontology at the Denver Museum of Nature & Science.

Initially, Lyson suspected it 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 didn't take long to determine they had found something more special. Lyson recalled that he started digging with Jessin where he thought he might find a neck bone.

"Instead of finding a , we found the with several teeth sticking out of it," Lyson said. "And it doesn't get any more diagnostic than that, seeing these giant tyrannosaurus teeth staring back at you."

In this photo provided by Giant Screen Films, 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. A documentary film caught the moment of discovery on camera. Credit: David Clark/Giant Screen Films via AP

A documentary crew with Giant Screen Films was there to capture the discovery.

"It was electric. You got goosebumps," recalled Dave Clark, who was part of the crew filming the documentary that later was narrated by Jurassic Park actor Sir Sam Neill.

Liam said his friends were dubious. "They did not believe me at all," he said.

He, Jessin and Kaiden—who the brothers consider to be another sibling—affectionately dubbed the fossil "The Brothers."

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 (1,587.57 kilograms)—about two-thirds of the size of a full-grown adult.

Ultimately, a Black Hawk helicopter airlifted the plaster-clad mass to a waiting truck to drive it to the Denver museum.

Lyson said more than 100 individual T. rex fossils have been unearthed, but many are fragmentary. It is unclear yet how complete this fossil is. So far, they know they have found a leg, hip, pelvis, a couple of tailbones and a good chunk of the skull, Lyson said.

  • In this image provided by 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. A documentary film crew captured the moment of discovery for the film "T.REX." Credit: David Clark/Giant Screen Films via AP

  • 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.” Credit: Andy Wood/Giant Screen Films via AP

  • In a scene from the documentary "T.REX," vertebrate paleontologist Tyler Lyson, Natalie Toth and the expedition team begin the work of uncovering a juvenile T. rex in the Hell Creek Formation in North Dakota. Credit: Andy Wood/Giant Screen Films via AP

  • This image provided by Giant Screen Films and taken from the film "T.REX,” shows a mother T. rex and her young. Credit: Courtesy of Giant Screen Films via AP

The public will get to watch crews chip away the rock, which the museum estimates will take about a year.

"We wanted to share the preparation of this fossil with the public because it is a remarkable feeling," Lyson said.

Jessin, a fan of the Jurassic Park movies and an aspiring paleontologist, has continued looking for fossils, finding a turtle shell just a couple days ago.

For other kids, he had this advice: "Just to put down their electronics and go out hiking."

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