An Ultimate Guide to Nanotyrannus: The Dwarf Tyrant

Leave a comment / / Updated on: 24th September 2023

Name MeaningDwarf TyrantHeight1.8 meters (6 feet)
PronunciationNAN-o-tie-RAN-usLength4.6 to 5.2 meters (15 to 17 feet)
EraMesozoicLate CretaceousWeight907 kg (2,000 lbs)
ClassificationDinosauria,‭ ‬Saurischia,‭ & TheropodaLocationUSA (North America)

Nanotyrannus Pictures

Nanotyrannus | Elenarts108 via Getty Images

The Nanotyrannus

Gage Beasley Prehistoric's Nanotyrannus Concept
Gage Beasley Prehistoric’s Nanotyrannus Concept

Earth, at some point in its prehistoric history, has served as home to many unique creatures.

While not all of these creatures are known, some have attained worldwide popularity, including dinosaurs.

Some dinosaurs are more popular than others, such as the Tyrannosaurus rex, which stands out as the undisputed king of the Late Cretaceous period.

However, in recent times, there have been several arguments in the scientific community regarding a potential close relative to the T.rex; the Nanotyrannus.

This creature’s name translates to dwarf tyrant, and the primary reason for the debate surrounding it is because experts initially categorized it as a distinct species.

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

However, other experts considered it to be a juvenile T.rex.

The Nanotyrannus was initially discovered in the 1940s by a team led by David H. Dunkle, then an undergraduate student at Yale University, from a site near the town of Jordan, Montana.

This first discovery included parts of an incomplete skull and it eventually gained popularity in 1988, after which it was officially named.

Paleontologist Robert T. Bakker, renowned for his work on dinosaur paleobiology, published a scientific paper describing the skull as a new genus and species, which he named Nanotyrannus lancensis.

Holotype Skull of the Nanotyrannus | James St. John via Flickr (CC BY 2.0)

The name Nanotyrannus derives from the Greek words nanos, meaning dwarf, and tyrannos, meaning tyrant, referring to its proposed smaller size compared to its famous relative, Tyrannosaurus rex.

Ever since its discocery and the publication of 1988, this creature’s popularity has grown in the realm of paleontology.

The rest of this article covers various aspects of the creature’s existence, all of which have been derived from extensive research and experiments over the years.

Keep reading to discover more about the Nanotyrannus.

Physical Characteristics 

Despite the arguments about whether or not the Nanotyrannus is related to the T.rex, when compared to it, it is significantly smaller.

Subsequent research and discoveries give experts reason to believe that the creature could reach between 15 and 17 feet, standing around six feet from the hip.

Gage Beasley Prehistoric's Nanotyrannus Size Comparison Chart
Gage Beasley Prehistoric’s Nanotyrannus Size Comparison Chart

It is also believed that the creature could weigh as much as 2,000 pounds, which is nothing compared to the size of the average T.rex.

While the Nanotyrannus shares many physical characteristics with T. rex, it possesses some distinctive traits that set it apart.

This dinosaur had a robust and muscular body, much like its larger relative, built for power and agility.

Its long, slender skull is one of its recognizable features, and measuring approximately 30 inches (76 centimeters) in length, the skull exhibits similarities to both T. rex and other small theropod dinosaurs.

As mentioned, the Nanotyrannus‘ skull was a blend of that of the T.rex and other smaller theropod dinosaurs, with a narrow snout and large, forward-facing eyes, suggesting excellent binocular vision.

The fenestrae (openings) that make up the rostrum, or the front portion of the skull, contribute to its lightweight construction.

Front of the Nanotyrannus | MR1805 via Getty Images

These air sacs presumably filled the antorbital fenestrae, which helped the skull to weigh less without sacrificing its strength.

Theropods frequently exhibited these modifications, which are thought to have been vital in preserving a healthy balance between strength and mobility.

The large, forward-facing eyes and binocular vision of Nanotyrannus indicate a predator that relied on depth perception and accurate targeting.

This suggests that it may have been an agile hunter, able to swiftly pursue and capture smaller, fast-moving prey.

Another feature of this creature that has caused even more debate is its dentition.

The Nanotyrannus‘ teeth are serrated and recurved, ideal for slicing through flesh and tearing apart prey.

Closeup of fossilized Tyrannosaur (Nanotyrannus) Tooth | CookiesForDevo via Getty Images

The creature possessed a unique dental formula, with a greater number of teeth than its larger relative, T. rex.

The premaxilla, the front portion of the upper jaw, contained six or seven teeth, while the maxilla, the main upper jawbone, housed around 14 teeth.

This distinct dental feature serves as evidence, for some experts, to the claim that the creature is a different genus from the T.rex.

However, alternative viewpoints propose that these distinctions may be attributed to the ontogenetic changes occurring during the growth and development of the individual dinosaur, suggesting Nanotyrannus might be a juvenile T. rex.

Experts believe, however, that the creature, despite its smaller size, had a relatively strong bite force, capable of inflicting significant damage to its prey.

Habitat and Distribution

Nanotyrannus roamed Earth, or parts of it that is now North America, in the Late Cretaceous period, approximately 68-66 million years ago.

Determining the precise habitat and distribution of Nanotyrannus is challenging due to the limited fossil evidence available.

Most of the knowledge regarding its habitat is inferred from the geological formations where its remains have been discovered.

According to experts, this creature lived in the same area of North America as the T.rex.

The Rocky Mountains were then rising in the far west, and a large portion of the area was covered by a small inland sea.

All year long, the weather was typically warm and humid, and the area was covered in oak, birch, conifer, and magnolia forests, as well as fern-, cypress-, and sequoia-like tree swamps along the coast.

Valley of the Ten Peaks and Moraine Lake, Banff National Park, Canada. (The Rocky Mountains) | Photo via Gorgo

There were many animals that we are familiar with today, including small mammals, birds, insects, snakes, crocodiles, amphibians, and plant-eating dinosaurs including Triceratops, Hadrosaurs, and Ankylosaurs.

The initial discovery of Nanotyrannus happened in Montana, USA.

Because of the creature’s presence in this region, experts believe that it likely inhabited various parts of the Western Interior of the United States, including South Dakota and Wyoming.

It is also believed that Nanotyrannus, like many other species during this period, migrated across the various continents, which were still joined as one supercontinent.

This supercontinent eventually broke apart later in the Late Cretaceous period, and it could have been affected by this continental fragmentation.

However, there is not enough evidence to prove this theory yet, as there have been no fossil discoveries of this creature in other continents.

Behavior and Diet

Nanotyrannus | Elenarts108 via Getty Images

Generally, determining the social behavior of any species is difficult, but it is even more difficult to determine the behavior of extinct creatures.

Nevertheless, several lines of evidence suggest that the Nanotyrannus may have exhibited some social behaviors.

The presence of multiple individuals found in close proximity at certain fossil sites implies the possibility of social groupings.

Some paleontologists propose that it, like its larger relative T. rex, may have engaged in pack hunting.

This hypothesis is based on the discovery of multiple individuals, ranging from juveniles to adults, found together in certain fossil assemblages.

Nanotyrannus Hunting Together | MR1805 via Getty Images

Pack hunting would have allowed them to coordinate their efforts in taking down larger prey, increasing their hunting success and overall survival.

The Nanotyrannus probably used a variety of displays and modes of communication to create and sustain social connections.

For territorial disputes, courtship, and dominance displays, visual cues including body postures and colour may have been utilised.

Long-distance communication between individuals may have used vocalisations, like roars and calls, which could have signalled their presence, hostility, or willingness for mating.

Also, the presence of juveniles alongside adults suggests the possibility of parental care and cooperative breeding in the Nanotyrannus.

Nanotyrannus hunting | Elenarts108 via Getty Images

Similar to modern-day birds, it is speculated that adults may have guarded nests and protected their young until they were able to fend for themselves.

Cooperative breeding, where multiple individuals assist in raising offspring, might have been beneficial for the survival and development of the young Nanotyrannus.

One of the primary indicators of an animal’s diet is its dentition.

The Nanotyrannus‘ teeth, in this instance, offer important information about its dietary preferences.

This creature had teeth that were sharp and serrated, and they were made specifically for grabbing and tearing flesh.

Fossilized Tyrannosaur (Nanotyrannus) Tooth | CookiesForDevo via Getty Images

The fact that the Nanotyrannus exhibited these traits, which are typical of carnivorous predators, suggests that its main source of nutrition was meat.

As a carnivorous dinosaur, it would have actively hunted and killed other dinosaurs and smaller prey animals.

While the exact prey preferences of the Nanotyrannus remain speculative, it is plausible that it targeted a variety of animals within its ecosystem.

This could include small to medium-sized herbivorous dinosaurs, such as ceratopsians, hadrosaurs, or ornithopods.

Additionally, it might have opportunistically fed on smaller reptiles, mammals, or even scavenged from carcasses of larger dinosaurs.

Life Cycle

Nanotyrannus dinosaur resting on a rock | Elenarts108 via Getty Images

The life cycle of the Nanotyrannus began with the hatching of its eggs.

It is believed that it laid a clutch of eggs, similar to other theropod dinosaurs.

The eggs were typically buried in nests to protect them from predators and environmental factors.

Once hatched, the hatchlings were likely vulnerable and required parental care to survive.

During their early years, Nanotyrannus individuals would have relied heavily on their parents for food and protection.

It is also possible that they exhibited different coloration patterns compared to adult Nanotyrannus, potentially helping to camouflage them in their environment.

As the creature grew, it went through several stages of development.

Nanotyrannus | MR1805 via Getty Images

By studying the fossilized remains of juvenile specimens, paleontologists have gained insights into the growth patterns of these dinosaurs.

The growth rate of Nanotyrannus appears to have been rapid during the first few years of life, similar to other theropod dinosaurs.

As they grew, their proportions changed, with their legs becoming relatively longer compared to their bodies.

It is estimated that Nanotyrannus reached sexual maturity at around 10 to 12 years of age, based on the growth rates of its closest relatives.

Sexual dimorphism may have existed within the species, meaning that males and females may have exhibited physical differences.

However, further research is necessary to confirm this hypothesis.

Evolution and History 

Reconstructed skeleton of “Jane” (Nanotyrannus), Burpee Museum of Natural History | Zissoudisctrucker via Wikipedia (CC BY-SA 4.0)

The story of Nanotyrannus began in the 1940s when fossil fragments were collected in Montana, USA.

One of the primary controversies surrounding it is whether it represents a distinct species or merely a juvenile form of Tyrannosaurus rex.

Some researchers argue that the differences observed in the skeletal features of Nanotyrannus specimens, such as the proportionally longer legs and different skull proportions, suggest a separate species.

On the other hand, proponents of the juvenile hypothesis propose that these differences can be explained by the natural variation among individuals of the same species.

Researchers have carefully compared and analyzed various Nanotyrannus and T. rex specimens, evaluating factors such as growth rates, bone histology, and cranial characteristics. 

Nanotyrannus | MR1805 via Getty Images

The examination of these traits aims to determine whether Nanotyrannus truly represents a distinct species or a developmental stage of T. rex.

In recent years, advancements in technology have offered new avenues for understanding the Nanotyrannus mystery.

High-resolution scanning techniques and sophisticated computer models have allowed scientists to examine the internal structures of Nanotyrannus bones, revealing insights into its growth patterns and skeletal development.

These findings have added valuable data to the ongoing discussion, further refining our understanding of this enigmatic dinosaur.

Interactions with Other Species 

Tyrannosaurus Rex Family Portrait | LindseyWArt via Deviant Art

Believed to be a smaller relative of Tyrannosaurus rex, Nanotyrannus likely occupied a niche as an agile predator, potentially targeting smaller prey.

Interactions with other theropods, including Tyrannosaurus rex, would have shaped Nanotyrannus‘ strategies and habitat selection.

To avoid direct competition, Nanotyrannus likely sought areas where T. rex was less dominant.

It may have also interacted with smaller theropods like Velociraptor and Dromaeosaurus, potentially competing for resources or scavenging opportunities.

Nanotyrannus and a Ceratops | MR1805 via Getty Images

Nanotyrannus‘ interactions with other species can be categorized as interspecies predation, intraspecific competition, and possible scavenging and commensalism.

It likely preyed upon smaller herbivorous dinosaurs, influencing their behavior and evolution.

If it was a distinct species, Nanotyrannus may have competed with juvenile T. rex for resources, shaping their growth and development.

Additionally, scavenging on larger dinosaur carcasses and benefiting from the hunting efforts of other predators could have also played a role in Nanotyrannus’ survival.

Cultural Significance 

Nanotyrannus was a theropod carnivorous dinosaur that lived in the Cretaceous Period of North America. | CoreyFord via Getty Images

Despite its small size compared to its famous relative Tyrannosaurus rex, Nanotyrannus has made a lasting impact on popular culture, scientific research, and education.

Its taxonomic classification has been a subject of intense debate among experts, with some arguing that it is merely a juvenile T. rex, while others support its status as a distinct genus.

Scientifically, the Nanotyrannus has contributed significantly to our understanding of dinosaur biology and evolution.

Despite the ongoing taxonomic controversy, studying its unique anatomy has provided valuable insights into tyrannosaurid growth patterns and ontogeny.

Confirming Nanotyrannus as a distinct genus could open doors to exploring the evolutionary divergence and ecological niches of smaller tyrannosaurs, challenging previous assumptions.

Nanotyrannus in Jurassic Fight Club | Photo via Jurassic Fight Club Fandom

Nanotyrannus also serves as a source of inspiration and education.

Its distinct appearance and controversial status captivate the imagination of dinosaur enthusiasts, young and old.

Exhibits in museums and educational materials featuring Nanotyrannus engage visitors in learning about paleontology, ancient ecosystems, and the scientific process.

By showcasing the complexity of prehistoric environments and the interconnectedness of species, Nanotyrannus sparks discussions and fosters a sense of wonder.


Nanotyrannus, whether a separate genus or a juvenile form of Tyrannosaurus rex, continues to be a subject of fascination and scientific debate.

Its smaller size and unique anatomical features have made it a captivating figure in popular culture, sparking the imagination of dinosaur enthusiasts worldwide.

Scientifically, Nanotyrannus has contributed to our understanding of dinosaur biology and evolution, shedding light on growth patterns and ontogeny.

It serves as an educational tool, inspiring curiosity and providing insights into the ancient world.

The cultural and scientific significance of Nanotyrannus ensures its enduring legacy as a symbol of the awe-inspiring diversity of prehistoric life.


Did Nanotyrannus hunt in packs?

There is evidence to suggest that Nanotyrannus individuals may have exhibited social behaviors, including pack hunting.

How does Nanotyrannus fit into the evolutionary history of tyrannosaurs?

If confirmed as a distinct genus, Nanotyrannus challenges previous assumptions about the size variations and ecological niches within the tyrannosaur family.

It offers an opportunity to explore the evolutionary divergence of smaller tyrannosaur species and their relationships with larger relatives like T. rex.


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