A team of paleontologists has finally settled a 40-year-old debate about the correct taxonomy for a handful of rare fossil specimens, confirming that Nanotyrannus is indeed a new species. The discovery was made using a well-preserved fossil known as "dueling dinosaurs," which was nearly mature at around 20 years old.
According to researchers, the "dueling dinosaurs" specimen provided all the necessary pieces to solve the long-standing debate about whether the fossils belonged to a juvenile Tyrannosaurus rex or a separate species. The team found that the fossil had much larger forelimbs than a T. rex, a possible vestigial third finger, fewer vertebrae in the tail, and more teeth in the skull.
The researchers also analyzed other tyrannosaur fossils and found that "Jane," another nearly complete fossil, belonged to Nanotyrannus but was not the same species as Nanotyrannus lancensis. They named the new species Nanotyrannus lethaeus.
The findings represent a significant blow to the juvenile T. rex interpretation, which has been widely accepted for decades. Even long-time T. rex proponents have expressed skepticism about the identification of "Jane" as a second species within the Nanotyrannus taxon.
"It's a decisive blow," said Thomas Holtz, a professor at the University of Maryland. The researchers' findings provide conclusive evidence that Nanotyrannus is a valid taxon and contains two species.
"This fossil doesn't just settle the debate; it flips decades of T. rex research on its head," said Lindsay Zanno, a paleontologist at North Carolina State University and head of paleontology at the North Carolina Museum of Natural Sciences. "It suggests that there could have been multiple tyrannosaur species, and we've been underestimating the diversity of dinosaurs from this period."
The discovery is significant not only because it resolves the debate but also because it provides new insights into the biology and behavior of these fascinating creatures. The "dueling dinosaurs" specimen has given paleontologists a rare glimpse into the life of a fully mature tyrannosaur, providing clues about its growth patterns, diet, and interactions with other species.
The study's findings have been published in the journal Nature and are available online at doi: 10.1038/s41586-025-09801-6.
According to researchers, the "dueling dinosaurs" specimen provided all the necessary pieces to solve the long-standing debate about whether the fossils belonged to a juvenile Tyrannosaurus rex or a separate species. The team found that the fossil had much larger forelimbs than a T. rex, a possible vestigial third finger, fewer vertebrae in the tail, and more teeth in the skull.
The researchers also analyzed other tyrannosaur fossils and found that "Jane," another nearly complete fossil, belonged to Nanotyrannus but was not the same species as Nanotyrannus lancensis. They named the new species Nanotyrannus lethaeus.
The findings represent a significant blow to the juvenile T. rex interpretation, which has been widely accepted for decades. Even long-time T. rex proponents have expressed skepticism about the identification of "Jane" as a second species within the Nanotyrannus taxon.
"It's a decisive blow," said Thomas Holtz, a professor at the University of Maryland. The researchers' findings provide conclusive evidence that Nanotyrannus is a valid taxon and contains two species.
"This fossil doesn't just settle the debate; it flips decades of T. rex research on its head," said Lindsay Zanno, a paleontologist at North Carolina State University and head of paleontology at the North Carolina Museum of Natural Sciences. "It suggests that there could have been multiple tyrannosaur species, and we've been underestimating the diversity of dinosaurs from this period."
The discovery is significant not only because it resolves the debate but also because it provides new insights into the biology and behavior of these fascinating creatures. The "dueling dinosaurs" specimen has given paleontologists a rare glimpse into the life of a fully mature tyrannosaur, providing clues about its growth patterns, diet, and interactions with other species.
The study's findings have been published in the journal Nature and are available online at doi: 10.1038/s41586-025-09801-6.
I mean, can you imagine the research that went into this? It's like they're proving a point to prove a point. And now we know about two species of Nanotyrannus... big whoop 
We'll probably just end up learning more about how these dinosaurs grew and ate and interacted with each other... how exciting 
Anyway, I guess this is some kind of significant moment in the world of paleontology... yay 
, it just goes to show how important a well-preserved fossil can be. I mean, who doesn't love a good "dueling dinosaurs" story? 
but seriously, this Nanotyrannus thing is interesting - two species, huh? that's some cool stuff for paleo enthusiasts. i'd love to see more info on the growth patterns and diet of these things tho 
i mean, a new species of dinosaur?! nanotyrannus lethaeus? that's like, so awesome! i love how scientists are still discovering new things about dinosaurs and it's making us realize how much we didn't know about them. and can u believe they found a nearly 20 year old fossil of a fully mature tyrannosaur 
It's crazy to think that "dueling dinosaurs" was this nearly mature specimen... that's wild! 
They're saying it proves there was another species besides T. rex, which is huge! My kids would freak out if they knew how diverse the ancient world was. I'm kinda glad we live in a time where science is all about discovery and exploring the past. It's mind-blowing to think about what else is out there waiting to be found 
. I mean, we already know they were like the apex predators of their time, but to think there might've been more than one species just adds another layer of complexity to our understanding of these awesome creatures 
. We used to think of T. rex as this one big, bad animal, but now we're realizing that maybe there was more to it than that 
. And let's not forget about the size difference between the arms and legs – it's like they had a superpower or something 
.
Nanotyrannus is officially a thing!!! I've been saying it 4 years now that those T-Rex fossils werent just juveniles lol and now its confirmed!! 
can't wait 2 learn more about Nanotyrannus lethaeus! 
