‘Dueling dinosaurs’ fossil long thought to include young T. rex actually contains different species: scientists

Two dinosaurs fossilized in combat, originally thought to involve a juvenile Tyrannosaurus rex testing its mettle against a Triceratops, actually feature a separate species frequently confused with the carnivore, scientists revealed Thursday.

The “dueling dinosaurs” fossil was first unearthed in Montana in 2006. At the time, it was assumed to depict a young T. rex fighting a Triceratops and was shelved to collect dust.

Scientists started to examine the fossil more microscopically after it was acquired by the North Carolina Museum of Natural Sciences in 2020 and finally made available for research.

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After a thorough five-year study, scientists confidently determined that the presumed teenage T. rex is actually an adult Nanotyrannus lancensis, a smaller species frequently confused with the king of the dinosaurs.

“Our specimen is a fully grown Nanotyrannus weighing only 1,500 pounds after two decades of growth,” said Dr. Lindsay Zanno, a co-author of the study from North Carolina State University and the head of paleontology at NCMNS, told The Guardian.

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“The anatomy of Nanotyrannus, from its higher tooth count, enlarged hands, shorter tail, unique pattern of cranial nerves and sinuses and smaller adult body size, is incompatible with the hypothesis that this skeleton is a teenage T. rex,” Zanno said.

The Nanotyrannus was believed to have been a newly discovered species in 1946, but the small skull branded with its name actually belonged to a juvenile T. rex.

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The pair operate as one another’s ugly cousin, so to speak. They’re similar in appearance, but boast vastly different features.

Namely, the Nanotyrannus had long legs and strong arms, whereas the T. rex is widely known for its imposing figure but scrawny arms.

The Nanotyrannus also grew to just 18 feet long, while the T. rex stretched to an imposing 42 feet.

The team released their full findings in an article published in Nature on Thursday. In it, they broadened their scope and properly identified another dinosaur skull discovered in 2001 that was also misclassified as a young T. rex.

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The skull, affectionately named Jane, was tied to a new species of Nanotyrannus, and the team still endeavors to right decades of misidentifications.

“For decades, palaeontologists have unknowingly used Nanotyrannus specimens as a model for teenage T. rex to understand the biology of Earth’s most famous dinosaur – studies of its locomotion, growth, diet and life history. Those studies need a second look,” she said.

The “dueling dinosaur” fossil still leaves more questions than answers as scientists now attempt to determine their causes of death and why they were so perfectly encased mid-battle.