Tag Archives: Nanotyrannus

New Study Confirms Nanotyrannus as a Distinct Species of Tyrannosaurid Dinosaur

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Nanotyrannus lansensis — For years, many believed these specimens were juvenile tyrannosaurus rex — However, a team of American paleontologists analyzed the ceratobranchia (hyoid bone) and concluded that it was actually a distinct, fully grown small tyrannosaurid. This finding shed light on the growth history of Nanotyrannus lansensis.

Encounter between adults of Nanotyrannus lansensis (left) and two juvenile tyrannosaurus rex, with a sub-adult tyrannosaurus rex watching from a distance. Image credit: Jorge Gonzalez.

Nanotyrannus lansensis measures 5.5 meters (18 feet) tall, which is relatively small compared to its length of over 12 meters (40 feet) compared to tyrannosaurus rex.

Initially discovered in 1942, Nanotyrannus lansensis was first classified as gorgosaurus, but through further scientific investigation, it was redefined as a separate species in 1988.

The main cause of the lengthy debate over the classification is that the holotype consists solely of an isolated skull, while traditional assessments of maturity often rely on limb bones.

Until recently, studies on other more complete fossils of Nanotyrannus lansensis yielded conflicting conclusions.

In a recent study, paleontologist Christopher Griffin from Princeton University and his team discovered that the microstructure of small bones in the throat ceratobranchial can accurately indicate the age and skeletal maturity of fossil specimens.

“At the time, there was a general consensus that the holotype skull of Nanotyrannus represented an immature tyrannosaurus rex rather than a distinct species,” Dr. Griffin stated.

“We initially aimed to follow that consensus, but upon examining samples of the hyoid bone and noticing characteristics strongly indicating maturity, we realized we needed to reevaluate that notion.”

The researchers found that in both modern archosaurs (like ostriches and crocodiles) and extinct theropods, the ceratobranch bones retain unique signals of growth and maturation, making them particularly useful for determining the developmental stage of fully mature individuals.

Using this technique, the team studied the holotype of Nanotyrannus lansensis and analyzed three sections of its ceratobranchia, identifying several features that suggest near-complete skeletal maturity.

This indicates that Nanotyrannus lansensis is a taxonomically distinct species that coexisted with tyrannosaurus rex, suggesting a greater diversity of predators in Late Cretaceous ecosystems than previously understood.

“This smaller-bodied tyrannosaurus rex indicates that the carnivore’s hyoid displayed a growth pattern suggesting it had reached or was close to maturity,” remarked paleontologist Ashley Poust of the University of Nebraska State Museum.

“We can now confidently affirm our classification of Nanotyrannus as separate from tyrannosaurus rex.”

“This implies the presence of at least two carnivores of different sizes in the same environment, which has significant implications for dinosaur ecology and extinction,” he added.

“Understanding what existed helps us gauge the size of the fossil record and how species have evolved over time.”

“Furthermore, it’s crucial to comprehend the complexity of the ecosystem.”

Results from this study are published in the journal Science.

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Christopher T. Griffin et al. A small Tyrannosaurus rex lived alongside tyrannosaurus rex. Science published online on December 4, 2025. doi: 10.1126/science.adx8706

Source: www.sci.news

New Research Uncovers Nanotyrannus as a Unique Dinosaur Lineage

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Paleontologists investigated a remarkably preserved and nearly mature Tyrannosaurus rex skeleton found in the Hell Creek Formation of Montana. Their findings suggest that this specimen exhibits traits similar to the holotype of Nanotyrannus and confirm that this lineage is distinct from tyrannosaurus.

A pack of Nanotyrannus daringly attacks a young tyrannosaurus rex. Image credit: Anthony Hutchings.

“This fossil turns decades of research on its head,” stated Dr. Lindsay Zanno, a researcher at North Carolina State University and the North Carolina Museum of Natural Sciences.

The researchers utilized tree ring data, spinal fixation, and developmental anatomy to show that the new specimen reached physical maturity at around 20 years.

Skeletal characteristics like larger forelimbs, more teeth, fewer caudal vertebrae, and distinctive skull neural patterns are established early in development and are biologically incompatible with tyrannosaurus rex.

“For Nanotyrannus to develop into a tyrannosaurus rex would contradict everything we know about vertebrate growth. That’s not just unlikely; it’s impossible,” remarked Dr. James Napoli, a researcher at Stony Brook University.

For years, paleontologists have incorrectly modeled tyrannosaurus growth and behavior using Nanotyrannus fossils.

This new evidence indicates that those studies were based on two entirely different species, suggesting that multiple tyrannosaurus species coexisted in the same ecosystem during the last million years before the asteroid impact.

As part of their study, Dr. Zanno and Dr. Napoli analyzed over 200 Tyrannosaurus fossils.

They found one skeleton, previously thought to represent a juvenile tyrannosaurus rex, that differed from the documented species Nanotyrannus lansensis, which is part of the renowned dueling dinosaur fossil.

The authors concluded that this specimen is a new species of Nanotyrannus, named Nanotyrannus letaeus.

The confirmation of Nanotyrannus implies that predator diversity during the final million years of the Cretaceous was far greater than previously understood, indicating that other small dinosaur species may also have been misidentified.

“This discovery provides a more complex and competitive view of the last days of the dinosaurs,” Dr. Zanno mentioned.

“With its massive physique, powerful bite, and stereoscopic vision, tyrannosaurus rex was indeed a fierce predator, but it did not dominate its environment without competition.”

“Darting together were Nanotyrannus — a slimmer, faster, more agile hunter.”

These findings were published in today’s edition of Nature.

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LE Zanno and JG Napoli. Nanotyrannus and tyrannosaurus coexisted at the end of the Cretaceous period. Nature published online October 30, 2025. doi: 10.1038/s41586-025-09801-6

Source: www.sci.news

Nanotyrannus: Dinosaur Skeleton Resolves Long-Standing Debate Over ‘Small Tyrannosaurus’ Fossil

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Artist’s interpretation of the pack Nanotyrannus assailing a young tyrannosaurus

Anthony Hutchings

Fossils previously thought to belong to a juvenile tyrannosaurus rex have been identified as a fully mature carnivore of a distinct species, resolving a long-standing debate in paleontology.

This controversy originated from a skull unearthed in the Hell Creek Formation in Montana during the 1940s, which was initially identified as gorgosaurus. It was later proposed to be a juvenile tyrannosaurus. In 1988, other researchers posited that the fossil represented an adult of a smaller related species, which they designated Nanotyrannus lansensis.

Since then, a number of additional fossils classified as Nanotyrannus have been discovered, although many paleontologists contend that they are merely tyrannosaurus juveniles.

Now, researchers have examined a complete skeleton for the first time, providing compelling evidence that Nanotyrannus is indeed a separate species.

The skeleton is among a pair of specimens known as “Dueling Dinosaurs,” found by private fossil hunters in 2006, which includes a triceratops and what was initially believed to be a juvenile T. rex buried approximately 67 million years ago.

It was only in 2020, when the fossil came into the possession of the North Carolina Museum of Natural Sciences, that paleontologists could conduct a thorough analysis of it.

“Upon receiving the specimen, we recognized it was extraordinary,” remarks Lindsey Zanno from the North Carolina Museum of Natural Science. “We had no inkling it would radically alter decades of research concerning the world’s most renowned dinosaur.”

Mr. Zanno collaborated with his colleagues, including James Naples, a postdoctoral researcher at Stony Brook University in New York. She had initially supported the juvenile tyrannosaurus theory but was compelled to reevaluate her stance based on the findings.

“Nanotyrannus displays unique nerve and sinus patterns, a greater number of teeth, larger hands, and shorter tails. These traits remain consistent as the species develops from juvenile to adult,” she notes.

Lindsay Zanno with the proposed Nanotyrannuslansensis skeleton

North Carolina State University

Zanno and Napoli’s examination of the dinosaur’s limb bones confirmed that it was a fully mature specimen, approximately 20 years old, weighing around 700 kilograms and measuring about 5.5 meters in length. “This is roughly one-tenth the weight of an adult human and half the length of a tyrannosaurus,” Zanno explains.

Additionally, Zanno and Napoli reanalyzed 200 tyrannosaur fossils and concluded that another nearly complete skeleton, known as Jane from the Hell Creek Formation, is misclassified as a tyrannosaurid fossil. They propose that Jane is actually a new species within this genus, designated Nanotyrannus letaeus.

“Although we possess only one skeleton of N. Retheus, its anatomy suggests it was part of a larger species,” remarks Zanno. “The configuration of the palatal sinuses and the shape of the bone behind the eye are distinctive.”

Proposed Nanotyrannus lansensis skull features more teeth than the tyrannosaurus skull.

Matt Zeher/North Carolina Museum of Natural Science

Scott Parsons, a researcher at the South Carolina State Museum, asserts that this latest study clarifies the debate surrounding Nanotyrannus being its own genus and species.

“In my opinion, Nanotyrannus was among the most formidable dinosaur predators, and being pursued by one would be quite a terrifying experience,” Parsons remarks, noting its long legs and fearsome thumb claws.

“In essence, we can compare Nanotyrannus and tyrannosaurus to modern-day cheetahs and lions. While they shared a similar overall anatomy, they had distinct hunting strategies.”

Thomas Carr from Carthage College in Wisconsin has expressed that the new findings are “quite definitive” that the dueling dinosaur specimen represents an almost adult species, one that differs from tyrannosaurus.

Additionally, Holly Ballard from Oklahoma State University, who led the 2020 research, stated that there is “no contention” regarding the team’s conclusion that the fossil belonged to an individual nearing adult size.

However, neither Ballard nor Carr are fully convinced that the other fossil, Jane, constitutes a new species of Nanotyrannus. “Jane is still maturing and large,” emphasizes Ballard, suggesting it may be a new taxon rather than a juvenile tyrannosaurus. “We’re returning to the old debates,” Ballard laments.

“Moreover, in the Hell Creek Formation, if there are numerous small tyrannosaurs in circulation, where are the juvenile tyrannosaurus? ” Kerr questions, stating that it complicates the fossil record. “We simply haven’t uncovered enough tyrannosaurs to fully elucidate what was occurring during the growth phases of the tyrannosaurids in the Hell Creek Formation.”

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Source: www.newscientist.com

Paleontologists identify Nanotyrannus as a distinct and small tyrannosaurus species

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Tyrannosaurus is one of the most intensively studied and best known dinosaurs. Nevertheless, their relationship and system are highly controversial. The ongoing discussion is Nanotyrannus lansensisinterpreted as either a separate genus of small-bodied tyrannosaurs, or a juvenile tyrannosaurus. tyrannosaurus rex. In a new study, paleontologists from the University of Bath and the University of Chicago examined multiple lines of evidence that Nanotyrannus lansensis as a separate species.

Nanotyrannus attack a boy tyrannosaurus. Image credit: Raul Martin.

first skull Nanotyrannus It was discovered in Montana in 1942, but paleontologists have debated for decades whether it was a separate species or just a juvenile of a much larger species. tyrannosaurus.

In the new study, paleontologist Nick Longlich of the University of Bath and paleontologist Evan Saitta of the University of Chicago reanalyzed the fossil and looked at its growth rings and body structure. Nanotyrannusand hitherto unrecognized fossils of youth tyrannosaurus.

Measuring tree rings Nanotyrannus They found that the bone was more densely packed toward the outside, indicating that bone growth was slowing down. That suggests these animals were nearly life-sized. It is not a young body that grows quickly.

Fossil growth modeling shows that the animal could have weighed between 900 and 1,500 kg and reached a maximum length of 5 meters, about 15% of the size of a giant. . tyrannosaurus8,000 kg and grew to over 9 m.

“I was quite surprised when I saw these results. I didn't expect to see such conclusive results,” said Dr. Longlich.

“If they were young tyrannosaurus They're supposed to grow like crazy and gain hundreds of pounds a year, but we don't see it that way. ”

“We tried modeling the data in different ways, but still got low growth rates. This seems to put an end to the hypothesis that these animals are young.” tyrannosaurus”

Researchers found no fossil evidence that combined both traits to support the existence of different species Nanotyrannus and tyrannosaurus —If one turns into the other, it will exist.

Every fossil they examined could be confidently identified as one or the other species.

The growth patterns of other tyrannosaurs were also inconsistent with the hypothesis that these tyrannosaurs were young. tyrannosaurus.

“If you look at other juvenile tyrannosaurs, you'll see a lot of characteristics that are typical of adults. Very young. tarbosaurus — next of kin of tyrannosaurus — exhibiting unique characteristics of adults,” Dr. Longrich said.

“Just as kittens look like cats and puppies look like dogs, the various juvenile tyrannosaurs are also unique. And Nanotyrannus nothing similar tyrannosaurus”

“It may have grown in a completely different way than other tyrannosaurs or other dinosaurs, but it's more likely that it simply wasn't a dinosaur. tyrannosaurus”

But it poses a mystery. Nanotyrannus not a boy tyrannosaurusSo why didn't anyone find the young man? tyrannosaurus?

“That was always one of the big questions. Well, it turns out we actually found it,” Dr. Longrich said.

“However, this fossil was collected many years ago, put away in a box of unidentified bones in a museum drawer, and then forgotten.”

Nanotyrannus They were lighter in build and had longer limbs than their stouter relatives. It also had larger arms, unlike those known for their short arms. tyrannosaurus.

“Actually, my arms are longer than people's.” tyrannosaurus.Even the biggest one tyrannosaurushave shorter arms and smaller claws than these smaller animals. Nanotyrannus. This was an animal whose arms were actually pretty scary weapons. It's actually a completely different animal, smaller, faster and more agile,” Dr. Longrich said.

“tyrannosaurus While animals relied on size and strength, this animal relied on speed. ”

“The long arms and other features suggest it was only a distant relative.” tyrannosaurus — and may have been sitting outside the family TyrannosauridaeWhich tyrannosaurus Part of the predatory dinosaur family. ”

a paper The survey results were published in a magazine fossil research.

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Nicholas R. Longrich and Evan T. Saitta. 2024. Taxonomic status of Nanotyrannus lansensis (Dinosaur: Tyrannosauridae) – A different taxon of small tyrannosaurs. Phos.stud 2 (1): 1-65; doi: 10.3390/fossils2010001

Source: www.sci.news