For years, the “dueling dinosaurs” in a North Carolina museum were believed to be a Triceratops and Tyrannosaurus rex.
However, an article published on October 30 in the journal Nature has a different take: The researchers believe that the T. Rex is actually a fully grown species called Nanotyrannus lancensis. Why does this matter?
It changes scientific understanding of the T. Rex, which is probably the most beloved and intriguing dinosaur.
- “What if everything we know about T. Rex growth is wrong? A complete tyrannosaur skeleton has just ended one of paleontology’s longest-running debates – whether Nanotyrannus is a distinct species, or just a teenage version of Tyrannosaurus rex,” the North Carolina Museum of Natural Sciences, where the “dueling dinosaurs” are housed, wrote in a press release.
- “The fossil, part of the legendary ‘Dueling Dinosaurs’ specimen unearthed in Montana, contains two dinosaurs locked in prehistoric combat: a Triceratops and a small-bodied tyrannosaur. That tyrannosaur is now confirmed to be a fully grown Nanotyrannus lancensis – not a teenage T. rex, as many scientists once believed,” the release continued.
- “This discovery paints a richer, more competitive picture of the last days of the dinosaurs,” Lindsay Zanno, associate research professor at North Carolina State University, says. “With enormous size, a powerful bite force and stereoscopic vision, T. rex was a formidable predator, but it did not reign uncontested. Darting alongside was Nanotyrannus – a leaner, swifter and more agile hunter.”
The legendary dueling dinosaurs have been the subject of much dispute among scientists.
“This fossil doesn’t just settle the debate. It flips decades of T. rex research on its head,” Zanno said in the museum’s release.
(photo by Mike Kemp/In Pictures via Getty Images)
“The implications are profound. For years, paleontologists used Nanotyrannus fossils to model T. rex growth and behavior,” the museum wrote. “This new evidence reveals that those studies were based on two entirely different animals – and that multiple tyrannosaur species inhabited the same ecosystems in the final million years before the asteroid impact.”
What Is a Nanotyrannus Dinosaur?
For nearly four decades, a small tyrannosauroid skull from Montana “has been the unlikely focus of a contentious scientific debate,” the journal article says.
The journal article describes Nanotyrannus as being “distinguishable from Tyrannosaurus by an abundance of traits, notably including smaller maximum body size and absolutely larger manus (forelimb).”
“We have the growth record preserved in the microstructure of the bone, which shows that it’s an adult,” said James Napoli, a paleontologist, told CNN.
“We document at least two co-occurring, ecomorphologically distinct genera in the Maastrichtian of North America, demonstrating that tyrannosauroid alpha diversity was thriving within one million years of the end-Cretaceous extinction,” the journal article continues.
According to the museum, “Using growth rings, spinal fusion data and developmental anatomy, the researchers demonstrated that the specimen was around 20 years old and physically mature when it died. Its skeletal features – including larger forelimbs, more teeth, fewer tail vertebrae, and distinct skull nerve patterns – are features fixed early in development and biologically incompatible with T. Rex.”
“For Nanotyrannus to be a juvenile T. Rex, it would need to defy everything we know about vertebrate growth,” says Napoli, the co-author, says in the museum’s press release. “It’s not just unlikely – it’s impossible.”
