Paleontologists have unearthed a previously unknown species of dinosaur in Mongolia’s Gobi Desert, revealing an unusual two-fingered adaptation that sets it apart from its relatives. The newly identified species, named Duonychus tsogtbaatari, adds to the growing body of research on therizinosaurs, a bizarre group of plant-eating theropods. This discovery not only expands our understanding of dinosaur evolution but also marks the first time a therizinosaur has been found with fewer than three claws.
Unique Discovery in the Gobi Desert
The fossil remains of Duonychus tsogtbaatari were found in the Bayanshiree Formation, a fossil-rich region in Mongolia’s Gobi Desert. This area is known for its abundance of late Cretaceous dinosaur fossils, with UNESCO recognizing it as one of the world’s most significant dinosaur fossil sites. The discovery was made by researchers from the Mongolian Academy of Sciences, alongside international paleontologists.
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Unlike other therizinosaurs, which typically had three claws on each hand, Duonychus tsogtbaatari possessed only two. The species’ name reflects this distinctive trait, with “Duonychus” translating to “two claws” in Greek, while “tsogtbaatari” honors Mongolian paleontologist Khishigjav Tsogtbaatar.
A Therizinosaur Unlike Any Other
Therizinosaurs were a peculiar group of theropod dinosaurs, distantly related to the carnivorous Tyrannosaurus rex but adapted for a herbivorous or omnivorous lifestyle. They are often characterized by their massive claws, long necks, and stocky bodies. However, Duonychus tsogtbaatari broke the mold with its two-fingered hands, making it the first known therizinosaur with this feature.
Dr. Darla Zelenitsky, a paleontologist at the University of Calgary and a co-author of the study, noted that therizinosaurs were already considered “awkward-looking” dinosaurs. Their most famous representative, Therizinosaurus, featured in Jurassic World Dominion, had enormous, scythe-like claws. However, Duonychus tsogtbaatari appears to have evolved a different strategy, with its two large, curved claws likely specialized for grasping vegetation, digging, or even defense.
Largest Preserved Claw Sheath
One of the most remarkable aspects of this discovery is the fossil’s preservation. Researchers found the first-ever keratinous sheath of a therizinosaur claw—an element akin to the outer covering of human fingernails. This sheath significantly increased the length and sharpness of the claws, likely making them more effective tools.
Paleontologist Yoshitsugu Kobayashi from Hokkaido University in Japan emphasized the importance of this find, noting that keratin is rarely preserved in fossils. “This newly discovered species from Mongolia breaks the mold with just two fingers instead of the typical three, offering a rare glimpse into how theropod hands evolved and adapted,” he explained.
Evolutionary Significance
The discovery of Duonychus tsogtbaatari sheds light on the evolutionary adaptations of therizinosaurs. Most theropod dinosaurs—including Tyrannosaurus rex—evolved reduced arm structures, but Duonychus represents a unique case of digit reduction within an herbivorous lineage.
Dr. Zelenitsky pointed out that while two-fingered theropods like T. rex are well known, Duonychus tsogtbaatari evolved this feature independently. This makes it a fascinating example of convergent evolution, where unrelated species develop similar traits due to comparable ecological pressures.
How Duonychus Used Its Claws
The function of Duonychus tsogtbaatari’s two-fingered hands remains a subject of speculation. Some researchers believe that the claws helped the dinosaur grip branches and pull vegetation closer—similar to the way chameleons use their limbs today. Others suggest that the claws may have played additional roles in defense, courtship displays, or even interspecies competition.
Steve Brusatte, a paleontologist at the University of Edinburgh, likened Duonychus tsogtbaatari to Edward Scissorhands due to its strange hands, but he also compared them to oversized tongs used for barbecuing. “Most therizinosaurs had three fingers, but this one is unique in having only two—so it really does look like a set of giant tongs,” he said.
Window into the Late Cretaceous
Estimated to have weighed around 260 kilograms (573 pounds) and stood about three meters (10 feet) tall, Duonychus tsogtbaatari lived during the Late Cretaceous period, between 100.5 and 66 million years ago. This was a time of significant evolutionary changes, as dinosaurs continued to diversify before the mass extinction event that ended their reign.
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The discovery of Duonychus tsogtbaatari provides new insights into how therizinosaurs adapted to their environments and adds to the growing knowledge of dinosaur evolution in Asia. The Gobi Desert continues to yield groundbreaking discoveries, reinforcing its status as a critical location for paleontological research.