A bizarre new species of dinosaur unearthed in Mongolia’s Gobi Desert is offering scientists one of the most detailed glimpses yet into the curious world of therizinosaurs—a group of plant-eating dinosaurs known for their massive claws and ungainly appearance.
Named Duonychus tsogtbaatari, the newly identified species stood around 10 feet (3 meters) tall, weighed approximately 573 pounds (260 kilograms), and bore distinctive two-fingered claws—one of which has been preserved with its keratin sheath still intact. The sheath, made of the same material as human fingernails, extends the length of the claw to nearly a foot, making it the largest fully preserved claw of its kind ever discovered.
“It’s close to a foot in size,” said paleontologist Darla Zelenitsky, associate professor at the University of Calgary and coauthor of the study published in iScience. “This is by far the biggest claw preserved for a dinosaur that has that keratinous sheath on it.”
The name Duonychus is derived from the Greek for “two claws,” while the species name honors Khishigjav Tsogtbaatar, a respected Mongolian paleontologist. Belonging to the therizinosaur lineage—members of the broader theropod group that includes Tyrannosaurus rex—these dinosaurs defy the predator mold. Instead, therizinosaurs are believed to have been herbivores or omnivores, using their imposing claws for feeding and possibly for defense.
In addition to the claw, the fossil includes parts of the dinosaur’s spine, tail, hips, arms, and legs. Based on its anatomy, researchers suggest that Duonychus used its claws to grasp vegetation, possibly handling branches up to 4 inches (10 cm) in diameter. The claws may have also played a role in social display behaviors or self-defense.
Experts liken the unusual appendages to those of a modern sloth, which uses long claws to cling to tree branches. However, in Duonychus, the oversized digits added an almost surreal twist—drawing comparisons to cult film character Edward Scissorhands for their exaggerated, blade-like appearance.
The fossil, first uncovered by Mongolia’s Institute of Paleontology under the Mongolian Academy of Sciences, marks an important addition to the growing record of Cretaceous-era life in Asia and sheds light on the remarkable evolutionary paths dinosaurs took before their extinction.
