Bactrosaurus: The Club Lizard from the Late Cretaceous Era

Welcome to a journey back in time, to an era when a unique dinosaur known as Bactrosaurus roamed the earth. This creature, whose name intriguingly translates to ‘Club Lizard’, is a marvel of the Late Cretaceous period. Let’s embark on an exploration of this fascinating creature, its origins, characteristics, and the world it inhabited.

Bactrosaurus Key Facts

Bactrosaurus pronunciationbak-truh-saw-ruhs
Meaning of nameClub Lizard
Type SpeciesBactrosaurus johnsoni
When it Lived89.8 to 70.6 MYA
PeriodLate Cretaceous
EpochConiacian to Late/Upper Campania
Length20.0 to 21.0 ft
Height6.6 ft
Weight1.2 tons
MobilityMoved on 2 legs
First Discovery1933 by Charles Gilmore
Location of first findGobi Desert, China
First Described by1933 by Charles Gilmore
HolotypeAMNH 6553

Bactrosaurus Origins: Taxonomy, Timeline, and Discovery

Bactrosaurus by Levi bernardo

The Bactrosaurus, or ‘Club Lizard’, derives its name from the Greek words ‘baktron’, meaning club, and ‘sauros’, meaning lizard. This dinosaur belongs to the Ornithopoda group, specifically the Hadrosaurid family. The genus includes the type species Bactrosaurus johnsoni and the subspecies Bactrosaurus prynadai.

It lived during the Late Cretaceous period, specifically from the Coniacian to the Late Campanian epoch. The first discovery of the Bactrosaurus was made in the Gobi Desert, China. American paleontologist Charles Gilmore first described this dinosaur in 1933. Since then, additional finds have been made in China, Mongolia, and Tajikistan, all dating back to the Cretaceous period.

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Fossil Evidence

A fossil display of a Bactrosaurus skeleton, showcased in a museum setting. The skeleton is laid out in a glass case, embedded in a sandy substrate to mimic its natural burial environment. Bactrosaurus, a herbivorous dinosaur from the Late Cretaceous period, is known for its sturdy build and beaked mouth.
Gary Todd, CC0, via Wikimedia Commons

The first Bactrosaurus fossils were discovered in the Gobi Desert, China. These initial findings consisted of partial skeletons of six individual Bactrosaurus johnsoni, ranging from possible hatchlings to full-sized adults. Charles W. Gilmore, who first described these fossils in 1933, named the dinosaur Bactrosaurus, or “club lizard”, in reference to the large club-shaped neural spines projecting from some of the vertebrae.

Later finds of Bactrosaurus fossils have been made in other parts of China, as well as in Mongolia and Tajikistan. These discoveries have provided valuable insights into the dinosaur’s physical characteristics and lifestyle and expanded its known geographical range.

Bactrosaurus Size and Description

Before we delve into the specifics of this dinosaur’s size and physical characteristics, let’s take a moment to appreciate its unique nature. As an early relative of the Lambeosaurus, it exhibits a number of intriguing features that set it apart from other dinosaurs of its time.

Short description of Bactrosaurus

It was an herbivorous dinosaur that exhibited a number of unique physical characteristics. Its body shape was robust, indicative of a powerful build for a hadrosaur. The dinosaur’s head was crestless, a feature that distinguishes it from many other hadrosaurs. The limbs, pelvis, and most of the skull are well-known, thanks to the fossil evidence that has been discovered.

Size and Weight of Type Species

A size comparison chart illustrating the type species Bactrosaurus johnsoni. This diagram shows the Bactrosaurus johnsoni, a herbivorous dinosaur from the Late Cretaceous period, in relation to a human figure for scale.
Slate Weasel, CC0, via Wikimedia Commons

A typical Bactrosaurus would have been 20–21 ft (6–6.5 m) long and weighed around 1.2 tons. Its femur measured 2.6 ft (80 centimeters) long. These measurements suggest that this was a medium-sized dinosaur, smaller than some of its hadrosaur relatives but still a noticeable presence in its environment.

The Dinosaur in Detail

This is a fascinating dinosaur, not just because of its size and physical characteristics, but also because of the unique features that set it apart from other dinosaurs. One of these features is its teeth. It had three stacked teeth for each visible tooth, a feature that is also seen in iguanodonts. This dental structure would have been advantageous for grinding down plant material, making this a highly efficient herbivore.

Another distinctive feature is its robust build. Despite being a hadrosaur, a group of dinosaurs known for their relatively slender bodies, it had a notably powerful build. This would have made it a formidable presence in its environment, capable of defending itself against predators.

Finally, it is notable for its crestless head. While many hadrosaurs had crests on their heads, the Bactrosaurus did not. This absence of a crest is seen as an anomaly among hadrosaurs and is one of the features that makes it unique.

The Bactrosaurus in its Natural Habitat and Environment

It lived in a world very different from our own. The Late Cretaceous period was a time of warm climates and high sea levels, with vast inland seas covering parts of the continents. The Asian landscape of this time would have been dominated by flowering plants, a relatively new development in earth’s history. The climate was generally warmer and more humid than today, probably because of very active volcanism associated with unusually high rates of seafloor spreading. The polar regions were free of continental ice sheets and their land was instead covered by forest. Dinosaurs roamed Antarctica even with its long winter night.

The Bactrosaurus, as an herbivorous dinosaur, would have relied heavily on the vegetation present during its time. The Late Cretaceous period saw the rise of flowering plants known as angiosperms which would have been a major food source for this dinosaur. Its powerful build and robust teeth would have allowed it to efficiently process this plant material in order to make it a highly effective herbivore.

The locomotion, moving on two legs, would have allowed it to navigate its environment with ease. This would have been particularly useful in the dense vegetation of the Late Cretaceous period. The powerful build and robust teeth would have also made it a formidable presence in its environment, capable of defending itself against predators.

Interesting Points about Bactrosaurus

  1. It is one of the earliest known hadrosauroids, making its discovery a significant finding in the field of paleontology.
  2. Despite the absence of a complete skeleton, it is one of the best-known early hadrosauroids.
  3. It exhibits a number of iguanodont-like features, including three stacked teeth for each visible tooth and a powerful build.
  4. In 2003, evidence of tumors was discovered in their fossilized skeletons, suggesting that these dinosaurs may have been susceptible to certain diseases.
  5. This was originally thought to be a lambeosaurine hadrosaurid, but recent studies place it as a more basal hadrosauromorph.

Contemporary Dinosaurs

The Bactrosaurus, a fascinating dino in its own right, shared its world with an intriguing ensemble of contemporary Asian dinosaurs. Among these were the Gilmoreosaurus, Saurolophus, Tarbosaurus, and Therizinosaurus. These dinosaurs perfectly showcase a wide arrange of adaptations and lifestyles and yet used these in the same environment.

The Gilmoreosaurus, a dinosaur considerably smaller than the Bactrosaurus, might have been a frequent sight in the same habitats. Despite their size difference, these two herbivores could have coexisted relatively peacefully, their diets possibly consisting of different plant types or parts, thus reducing direct competition. The Saurolophus, another herbivore, was roughly the same size as the Bactrosaurus. Unlike the Gilmoreosaurus, their similar sizes might have led to competition for the same food resources.

The Tarbosaurus, a large carnivorous dinosaur, introduces a different dynamic to this prehistoric scene. As a predator, it might have posed a threat to the Bactrosaurus and added a layer of danger and urgency to its daily life. The presence of such a formidable predator would have undoubtedly influenced the behavior and habits of the Bactrosaurus, possibly leading to the development of defensive strategies or behaviors.

Lastly, the Therizinosaurus—with its long, clawed forelimbs—presents an interesting contrast to the Bactrosaurus. Despite its intimidating appearance, the Therizinosaurus was likely an herbivore or possibly an omnivore. Its presence adds to the rich diversity of life that surrounded the Bactrosaurus, further illustrating the complexity of this prehistoric ecosystem. Through this exploration, we gain a deeper understanding of the Bactrosaurus’s life and environment, shedding light on the intricate interplay of survival, competition, and coexistence in the prehistoric world.

Frequently Asked Questions

What does the name Bactrosaurus mean?

The name translates to “club lizard”. This name is derived from the Greek words “baktron“, meaning club, and “sauros“, meaning lizard.

What was its diet?

It was an herbivore, meaning it primarily consumed plant material.

When did this dinosaur live?

It lived during the Late Cretaceous period, specifically from the Coniacian to Late Campanian epochs, which is approximately 89.8-70.6 million years ago.

Where was it first discovered?

The first fossils were discovered in the Gobi Desert, China. These were described in 1933 and subsequent finds have been made in Mongolia and Tajikistan as well as China.

What are some of its unique features?

It is notable for its robust build, crestless head, and unique dental structure, which included three stacked teeth for each visible tooth.

What was its environment like?

This herbivore lived during a time of warm climates and high sea levels with vast inland seas covering parts of the continents. The landscape would have been dominated by flowering plants, a relatively new development in the history of earth’s vegetation.


This article was last fact checked: Joey Arboleda, 06-10-2023

Featured image Credit: Levi bernardo, CC BY-SA 3.0, via Wikimedia Commons