Bizarre New Dinosaur Discovered with Two-Fingered Hands Like Tyrannosaurus
April 21, 2025
An international research team, including North Carolina Museum of Natural Sciences paleontologist Chinzorig Tsogtbaatar, has discovered a new species of therizinosaur from the Late Cretaceous Bayanshiree Formation (~96-90 million years old) in the Gobi Desert of Mongolia. The dinosaur was named Duonychus tsogtbaatari, in honor of Chinzorig’s father, influential Mongolian paleontologist Khishigjav Tsogtbaatar.
Unlike other therizinosaurs, which possess tridactyl (three-fingered) hands with large claws adapted for grasping vegetation, Duonychus is didactyl (two-fingered), akin to Tyrannosaurus. Additionally, the preserved claw sheath retains an almost complete three-dimensional structure, representing a rare instance of keratin preservation in medium to large theropods.
Therizinosaurs (Therizinosauria) were theropod dinosaurs that lived during the Cretaceous period (~145-66 million years ago) in Asia and North America. They are characterized by long necks, small leaf-shaped teeth, and large hooked claws on three-fingered hands. The large therizinosaur Therizinosaurus, discovered in Mongolia in the late 1940s, gained widespread recognition after appearing in the film “Jurassic World.”
The discovery of Duonychus tsogtbaatari provides a significant opportunity to investigate therizinosaur hand evolution and the mechanisms behind digit reduction. The research analyzes the morphological characteristics and exceptionally preserved keratinous claw sheath of this new species to offer novel insights into dinosaur evolution and behavior.
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