Young Rex

Fossils of a juvenile tyrannosaurus were found while hiking in the Hell Creek Formation in 2022, and the bones were finally excavated in 2023. The partial skeleton, one of the few juvenile tyrannosaur specimens ever found, will go on display at the Denver Museum of Nature and Science later this month, coinciding with the release of a new documentary about the find.

young specimens [T. rex] extremely rare. The finding is of great importance to researchers because the “Young Rex” specimen could help answer questions about how the king of dinosaurs grew up.
says Tyler Lyson, the museum’s vertebrate paleontologist who led the Teen Rex dig.

“Teen Rex” was 7.6 meters long and weighed about 1,600 kilograms when it died 66 million years ago. For comparison, an adult tyrannosaurus reached about 12 meters in length and weighed about 3,600 kilograms.

Brothers Liam and Jessin Fisher, ages 7 and 10, were with their father, Sam Fisher, and their 9-year-old cousin, Caden Madsen, when they saw the large fossil emerging from the rock. Sam Fisher was a former classmate of Tyler Lyson, so he informed the paleontologist about his findings.

Denver Museum of Nature and Science volunteer Aidan Skelly poses next to the partial skeleton of a young tyrannosaur / Photo: Dr. Tyler R. Lyson

The statement stated that Lyson began digging for fossils 11 months later with a team consisting of three boys, as well as Liam and Jessina’s 14-year-old sister, Emmalynn Fisher. Set Many fossils, including a tooth, were unearthedLyson immediately identified it as belonging to a tyrannosaurus.

Lyson and colleagues estimated the size of a juvenile T. rex based on its tibia (lower leg), which was 82 centimeters long. The tibia of an adult T. rex was approximately 112 centimeters long, indicating that this dinosaur was a teenager.

Researchers will analyze the bones in more detail to confirm the dinosaur’s age and learn more about the growth and development patterns of T. rex bones. This work will be performed publicly at the museum as part of a new temporary exhibition called “Discovering Tyrannosaurus,” which will be open to visitors starting June 21.

The “T. rex” documentary, scheduled to premiere the same day, will show footage from the discovery of “Teen Rex” and use computer graphics to bring T. rex to life from birth to adulthood.