Nanosaurus: Unveiling the Dwarf Lizard of the Late Jurassic Era

Let’s embark on a journey back in time, to an era when colossal creatures roamed the Earth. Among these ancient giants, there existed a rather diminutive yet fascinating dinosaur known as Nanosaurus. Despite its small stature, this creature holds a significant place in the grand tapestry of prehistoric life. As we delve into the world of Nanosaurus, we’ll uncover intriguing details about its existence, characteristics, and the environment it thrived in during the Late Jurassic Period.

Nanosaurus Key Facts

Meaning of nameSmall or dwarf lizard
Type SpeciesNanosaurus agilis
When it Lived155.7 to 145.0 MYA
PeriodLate Jurassic
EpochLate/Upper Kimmeridgian to the top of the Early/Lower Tithonian
Length6.6 to 7.2 feet
HeightAround 1 foot
Weight44 to 66 lbs
MobilityMoved on two legs
First Discovery1877 by Othniel Charles Marsh
Location of first findMorrison Formation, USA
First Described by1877 by Othniel Charles Marsh
HolotypeYPM VP 1913

Nanosaurus Origins, Taxonomy and Timeline

Nanosaurus, meaning ‘small or dwarf lizard’, is a name derived from Latin and Greek origins. The Latin ‘nanus’ translates to ‘dwarf’ while the Greek ‘sauros’ translates to ‘reptile’ or ‘lizard’. This nomenclature aptly reflects the relatively diminutive size of this dinosaur.

Illustration of Othnielosaurus, a small bipedal herbivorous dinosaur from the Late Jurassic period. This dinosaur is depicted with a slender build and striped tail, showcasing its agility and speed. Othnielosaurus, known for its lightweight frame and adaptability, inhabited what is now North America.

Belonging to the Cerapod group, this dinosaur is classified within the Ornithopoda family. Its type species, Nanosaurus agilis, is the only species in the genus. This classification places it among a group known for their bipedal mobility and plant-eating habits. The timeline of this herbivorous dinosaur spans the Late Jurassic Period, specifically from the Late Kimmeridgian to the Early Tithonian Epochs.

Discovery & Fossil Evidence

Fossilized skeleton of Othnielosaurus displayed in a museum exhibit, accompanied by a detailed anatomical diagram. This specimen highlights the skeletal structure of the small, bipedal herbivorous dinosaur from the Late Jurassic period.
.Skull-less skeleton of a juvenile Nanosaurus skeleton (BYU 163), Carpenter, Kenneth, CC BY-SA 4.0, via Wikimedia Commons

The discovery of Nanosaurus is a tale of scientific intrigue and evolving understanding. Its taxonomic classification has changed many times over the years as new research revealed more information. Othniel Charles Marsh, a pioneer in paleontology, first named Nanosaurus in 1877 based on partial remains from Colorado’s Morrison Formation. Initially, he identified two species: Nanosaurus agilis, from fragmentary remains including a dentary, and Nanosaurus rex, based on a complete thigh bone. For a short time he also named a third species to this genus, Nanosaurus victor. The narrative became more complex when Marsh introduced the genus Laosaurus in 1878, adding several species to the mix.

Display of Othnielia skeletons in a museum exhibit, showing a group of these small, bipedal herbivorous dinosaurs from the Late Jurassic period. The arrangement of the skeletons highlights their agile build and lightweight frame.
Cast mounted as if a herd running, Denver Museum of Nature and Science. Firsfron, CC BY-SA 3.0, via Wikimedia Commons
Exhibit of an Othnielosaurus skeleton in a museum, displayed in a lifelike pose among ferns. This setup highlights the agile build and lightweight frame of Othnielosaurus, a small bipedal herbivorous dinosaur from the Late Jurassic period.
Reconstructed skeleton cast, Dinosaur Journey Museum, Jens Lallensack, CC BY-SA 4.0, via Wikimedia Commons

 However, it was in the 1970s and 1980s that paleontologist Peter Galton significantly revised the taxonomy, introducing the genus Othnielia for species previously assigned to Nanosaurus and Laosaurus. In the early 2000s, other genera were introduced such as Othnielosaurus and Drinker. The most transformative development occurred in 2018 when Galton and Kenneth Carpenter described a new ornithischian specimen. This specimen bore striking similarities to the fragmentary holotype of Nanosaurus. This led to the unification of all of these species under the name Nanosaurus agilis, painting a new picture of this small dinosaur as a common and well-represented species in the fossil record.

Two fossil slabs containing Othnielosaurus remains, showcasing the preserved bones of this small bipedal herbivorous dinosaur from the Late Jurassic period. The slabs are displayed with a scale for reference, highlighting the delicate and intricate nature of the fossilized bones.
Type specimen of Nanosaurus agilis Marsh 1877 (YPM VP 1913) as illustrated in 1908 and cast of the bone impressions after the fragmentary bone was removed. Carpenter, Kenneth, CC BY-SA 4.0, via Wikimedia Commons

This journey, from initial discovery to contemporary understanding, showcases the dynamic nature of paleontology, where each discovery and revision brings us closer to understanding the ancient world of dinosaurs like Nanosaurus.

Nanosaurus Size and Description

Through this long and ever-changing history, this species has been studied often by many people. Let’s delve into the physical attributes of Nanosaurus, a creature that, despite its small size, played a significant role in the Late Jurassic ecosystem.

Short description of Nanosaurus

It was a bipedal dinosaur, distinguished by its short forelimbs and elongated hindlimbs that were well-adapted for swift movement. The large processes on its hindlimbs indicate strong muscle attachments, hinting at a potentially agile lifestyle. Its hands were short and broad, with compact fingers, while its head was relatively small compared to its body. Its body is well-known but the skull still lacks fossil evidence.

Size and Weight of Type Species

Size comparison diagram showing O. consors, the type species of Othnielosaurus, next to a human figure for scale. This illustration highlights the small size of O. consors, a bipedal herbivorous dinosaur from the Late Jurassic period.
PaleoGeekSquared, CC BY-SA 4.0, via Wikimedia Commons

As the name suggests, this was indeed a small dinosaur. Specimens previously assigned to Drinker and Othnielosaurus measured between 6.6 to 7.2 feet in length and weighed approximately 44.0 to 66.0 pounds. This modest size sets it apart from many of its contemporaries, which often reached much larger dimensions.

The Dinosaur in Detail

Nanosaurus, though small, possessed unique features that set it apart. Its bipedal locomotion, for instance, suggests a lifestyle that required agility and speed for foraging or evading predators. This adaptation not only highlights its survival instincts but also provides a window into the diverse evolutionary paths of dinosaurs.

This herbivorous dinosaur possessed small leaf-shaped cheek teeth which were triangular with small ridges and denticles lining the front and back edges. The teeth in the premaxillary region had less ornamentation, suggesting a diet that primarily consisted of plant material. This dental arrangement, combined with its physical build, paints a picture of a dinosaur well-suited to a herbivorous lifestyle in the diverse ecosystems of the Late Jurassic Period.Notable specimens, such as the holotype YPM VP 1913, have been instrumental in piecing together the puzzle of Nanosaurus’ existence. These fossils offer a tangible link to a bygone era, allowing us to reconstruct aspects of this dinosaur’s life and behavior.

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Interesting Points about Nanosaurus

The Nanosaurus in its Natural Habitat

Here, we find ourselves transported to a landscape vastly different from our own. North America was fused with Asia at this time, creating a paleocontinent known as Laurasia. The Late Jurassic Period was characterized by diverse ecosystems, with a climate that supported a rich array of flora and fauna.

As an herbivore, Nanosaurus fed on the vegetation of its time. Its bipedal mobility suggests it could have navigated through various terrains in search of food. While the specifics of its diet remain speculative, it likely included a range of plant material available in its habitat. The Morrison Formation has also yielded plant fossils such as cycads, gingkoes, ferns, horsetails, and various trees, to name a few.

Its social behavior is a subject of intrigue. Whether it was a solitary wanderer or moved in herds is a question that adds depth to our understanding of its life. Many museum displays show them engaging in social behavior such as running in herds or fighting, but this behavior remains speculative.

Contemporary Dinosaurs

In the lush world of the Late Jurassic Period, a tiny, sprightly creature darted through the underbrush. This pint-sized dinosaur, no larger than a modern turkey, was a mere speck in a land of giants. Its life was a constant dance of dodging and weaving with behemoths like Apatosaurus lumbering nearby. The Nanosaurus, however, had more pressing concerns than being inadvertently stepped on. In the shadows lurked the menacing Torvosaurus, a predator as fearsome as its name suggests. This massive beast was larger than a school bus. It was a stark contrast to the diminutive Nanosaurus. Imagine a cat-and-mouse game where the Nanosaurus had to rely on its agility and wits to outmaneuver this formidable predator, turning the dense foliage into its ally in this deadly game of hide and seek.

Amidst these titans, Elaphrosaurus roamed. This dinosaur, roughly the same size as the menacing Torvosaurus, was a wild card in the Nanosaurus’ daily struggle. While not as bulky, Elaphrosaurus was a swift and agile hunter that the Nanosaurus would have had to work to avoid. This added an extra layer of complexity to the already intricate dance of survival our main dinosaur had to perform.

Frequently Asked Questions

When was this dinosaur first discovered?

It was first discovered in 1877 by Othniel Charles Marsh.

What does its name mean? 

The name means ‘small or dwarf lizard’ and comes from both Latin and Greek origins.

What type of diet did it have?

It was an herbivore, feeding on the diverse plant material of the Late Jurassic.

In which period did it live?

It lived during the Late Jurassic Period, approximately 155.7 to 145.0 million years ago.

Where have its fossils been found?

Fossils have been found in Southwestern North America, in states such as Colorado, Wyoming, and South Dakota.


The information in this article is based on various sources, drawing on scientific research, fossil evidence, and expert analysis. The aim is to provide a comprehensive and accurate overview of the Nanosaurus. However, please be aware that our understanding of dinosaurs and their world is constantly evolving as new discoveries are made.

This article was last fact-checked: Joey Arboleda, 11-03-2023