Adasaurus: The Late Cretaceous Predator from Mongolia

Adasaurus: The Late Cretaceous Predator from Mongolia

Imagine a time when fearsome predators roamed the Earth, their dominance etched in the fossilized sands of Cretaceous landscapes. One such remarkable creature is Adasaurus, a cunning carnivore that prowled the Nemegt Formation in Mongolia during the Late Cretaceous Period. This “Evil Lizard,” named from the Mongolian and Greek words for evil spirit and lizard, respectively, offers a captivating glimpse into the dynamic and often perilous world of ancient theropods.

First unearthed in 1977 by the esteemed paleontologist Rinchen Barsbold, Adasaurus has intrigued scientists and dinosaur enthusiasts alike with its unique blend of characteristics. This dromaeosaurid, or raptor, stands out not only for its fearsome name but also for its intriguing evolutionary adaptations and interactions with contemporary dinosaurs. As we delve deeper into the life and times of this ancient predator, we’ll explore its origins, fossil discoveries, and the remarkable ecosystem it once dominated.

Adasaurus Key Facts

Meaning of nameEvil Lizard
Type SpeciesAdasaurus mongoliensis
When it Lived72.1 to 66.0 MYA
PeriodLate Cretaceous
Length7.8 to 11.5 ft
Height3.3 ft at hips
Weight80.0 to 192.0 lbs
MobilityMoved on two legs
First Discovery1977 by Rinchen Barsbold
Described by1983 by Rinchen Barsbold
HolotypeMPC-D 100/20
Location of first findNemegt Formation, Mongolia

Adasaurus Origins, Taxonomy, and Timeline

Adasaurus, whose name translates to “Evil Lizard,” draws from the Mongolian word “Ada” meaning evil spirit, and the Greek word “sauros” meaning lizard. This evocative name reflects both the predatory nature and the cultural influences surrounding its discovery. Pronounced AH-da-SAW-rus, the name conjures images of a formidable creature stalking the ancient landscapes of Mongolia.

Adasaurus: Discover the Agile Predator of the Late Cretaceous. Explore the fascinating world of Adasaurus, the "Evil Lizard" from Mongolia's Late Cretaceous Period. Learn about its habitat, behavior, and more.

Taxonomically, Adasaurus belongs to the Theropoda, within the Dromaeosauridae, known for their agility and predatory prowess. Its ype species is A. mongoliensis, which remains the only species identified within the genus. This classification places it among a fascinating group of raptors with certain physical traits and hunting strategies.

The timeline of Adasaurus extends from approximately 72.1 to 66.0 million years ago, during the Maastrichtian of the Late Cretaceous Period. This era was characterized by significant evolutionary changes and the dominance of dinosaurs across various ecological niches, follow by the extinction of all non-avian dinosaurs.

Listen to Pronunciation

To listen to the correct pronunciation of Adasaurus, check out this video.

Discovery & Fossil Evidence

The initial discovery of Adasaurus dates back to 1977, when Rinchen Barsbold unearthed its fossils in the Nemegt Formation of Mongolia. This region, known for its rich Cretaceous fossil beds, has provided a treasure trove of information about Late Cretaceous fauna. The holotype specimen, catalogued as MPC-D 100/20, includes well-preserved skeletal remains that have allowed paleontologists to reconstruct much of its anatomy and hypothesize about its behavior.

Reconstructed skull of the dromaeosaurid Adasaurus mongoliensis.
Reconstructed skull of the dromaeosaurid A. mongoliensis.
PaleoNeolitic, CC BY-SA 4.0, via Wikimedia Commons

Subsequent finds have been limited, making Adasaurus a relatively rare but significant member of the Dromaeosauridae. The fossils primarily consist of partial skeletons, including elements of the skull, vertebrae, and limbs. These discoveries offer valuable insights into the physical characteristics and evolutionary relationships of this intriguing predator.

Despite the scarcity of extensive fossil material, the specimens available reveal a creature adapted for a predatory lifestyle. The preservation of these fossils, although not complete, provides a window into the past, showcasing the unique adaptations that enabled Adasaurus to thrive in its environment.

Adasaurus Size and Description

Adasaurus was a medium-sized Theropoda, distinguished by its agile and sleek body built for hunting. Its overall body shape was streamlined, with a relatively small head equipped with sharp teeth and a keen sense of sight. The neck was flexible, allowing for a wide range of motion, while the vertebrae were robust, supporting a strong and muscular frame. The limbs were well-developed, with powerful hind legs that facilitated swift and agile movements. Its tail, long and rigid, provided balance and stability during high-speed chases. Although its skin and exact coloration remain speculative, it is likely that Adasaurus had a covering of feathers or proto-feathers, as suggested by related dromaeosaurids.

Size and Weight of Type Species

Size of the medium-sized dromaeosaurid Adasaurus mongoliensis compared to a 1.8 m (5.9 ft) tall human.
PaleoNeolitic, CC0, via Wikimedia Commons

The type species, Adasaurus mongoliensis, measured between 7.8 to 11.5 feet in length, standing approximately 3.3 feet tall at the hip. Its weight ranged from 80.0 to 192.0 pounds, reflecting a lean and agile build. These dimensions indicate a predator well-suited for chasing down prey, with a physique designed for speed and precision. Estimates of its size and weight vary slightly among paleontologists, but the consensus points to a relatively lightweight yet formidable hunter within its ecological niche.

Adasaurus in Detail

Adasaurus possessed several distinctive features that set it apart from other theropods. Its sickle-shaped claws on the second toes of its hind legs were particularly notable, adapted for grasping and slicing through the flesh of its prey. This adaptation is shared with other dromaeosaurids, highlighting a specialized predatory strategy. The structure of its jaws and teeth suggests a diet primarily consisting of small to medium-sized vertebrates, possibly including other dinosaurs.

The skeletal structure of Adasaurus reflects its adaptability and survival instincts. The robust yet lightweight bones facilitated swift movements, while the elongated limbs provided leverage and power during hunting. These physical attributes underscore the evolutionary success it had in the competitive ecosystems of the Late Cretaceous.

Notable specimens of Adasaurus have contributed significantly to our understanding of dromaeosaurid diversity and evolution. The detailed study of these fossils has shed light on the intricate relationships between various theropod species and their respective ecological roles. Each discovery adds a piece to the puzzle, enhancing our knowledge of this enigmatic predator.

Contemporary Dinosaurs

Living alongside Adasaurus were several other fascinating dinosaurs that shared their habitat and contributed to the dynamic ecosystem of the Nemegt Formation.

One such contemporary was Mononykus, an alvearezsaurid. This smaller but equally agile predator likely competed with Adasaurus for similar prey, creating a complex web of interactions and rivalries. The coexistence of these two raptors offers a glimpse into the competitive nature of their environment, where only the most adaptable survive.

Protoceratops, a herbivorous dinosaur, also inhabited the same region. While not a direct competitor, its presence added to the diversity of the ecosystem. Protoceratops likely served as prey for Adasaurus, illustrating the intricate food web that sustained these ancient communities.

Oviraptor, another intriguing dinosaur of the time, may have shared nesting grounds with Adasaurus. Although primarily known for its egg-stealing reputation, Oviraptor’s omnivorous diet meant that it could exploit a variety of food sources, reducing direct competition with the carnivorous Adasaurus. This coexistence highlights the varied survival strategies employed by different species.

Tarbosaurus, a massive tyrannosaurid, represented the apex predator of the region. While they occupied different niches, the presence of such a formidable hunter would have influenced the behavior and territorial dynamics of smaller predators. Understanding these relationships helps paint a vivid picture of the predator-prey dynamics within this ancient ecosystem.

Interesting Points about Adasaurus

Adasaurus in its Natural Habitat

The natural habitat of Adasaurus was the Nemegt Formation, characterized by a semi-arid climate with seasonal variations. This environment included river channels, floodplains, and a variety of vegetation, ranging from coniferous trees to flowering plants. Such a diverse landscape provided ample opportunities for hunting and nesting.

Restoration of Therizinosaurus, Tylocephale (actually Prenocephale) and Velociraptor (actually Adasaurus).

Adasaurus, being a carnivore, primarily hunted smaller dinosaurs and possibly other vertebrates. Its agility and speed, facilitated by its powerful hind legs, made it an effective predator. The presence of its sickle-shaped claws suggests a reliance on ambush tactics, using its claws to latch onto prey and deliver fatal bites.

Social behavior of Adasaurus is still a subject of speculation, but it may have been a solitary hunter or operated in small packs, similar to other dromaeosaurids. Its keen senses, particularly sight and smell, would have been crucial for locating prey in the varied terrain of its habitat. These adaptations not only ensured its survival but also influenced the ecological balance of its environment.

Frequently Asked Questions

What does Adasaurus mean?

Adasaurus means “Evil Lizard,” derived from the Mongolian word for evil spirit and the Greek word for lizard.

When did Adasaurus live?

Adasaurus lived during the Late Cretaceous Period, approximately 72.1 to 66.0 million years ago.

What was the diet of Adasaurus?

Adasaurus was a carnivore, primarily hunting smaller dinosaurs and other vertebrates.

When was Adasaurus discovered?

Adasaurus was first discovered in 1977 by Rinchen Barsbold in the Nemegt Formation of Mongolia.

What was the size of Adasaurus?

Adasaurus measured between 7.8 to 11.5 feet in length and weighed between 80.0 to 192.0 pounds.

What distinguishes Adasaurus from other theropods?

Adasaurus is notable for its sickle-shaped claws on its hind legs, adapted for grasping and slicing prey.


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 Adasaurus. 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, 05-30-2024

Featured Image Credit: PaleoNeolitic, CC BY-SA 4.0, via Wikimedia Commons

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