Paleontologists have unearthed the fossilized stays of a brand new and strange therizinosaurid dinosaur with atypical fingers in Mongolia.
Life reconstruction of Duonychus tsogtbaatari. Picture credit score: Masato Hattori.
Duonychus tsogtbaatari lived in what’s now Mongolia throughout the Late Cretaceous epoch, between 95 and 90 million years in the past.
The brand new species belongs to Therizinosauria, a bunch of herbivorous or omnivorous theropod dinosaurs that lived in Asia and North America throughout the Cretaceous.
“Therizinosauria is a clade of bizarre herbivorous or omnivorous theropod dinosaurs identified from Cretaceous deposits of Asia and North America,” Hokkaido College Museum vertebrate paleontologist Yoshitsugu Kobayashi and his colleagues wrote of their paper.
“This clade is most recognizable for his or her tridactyl (three-fingered) fingers sporting three giant claw-like unguals, as exemplified by the large-bodied Therizinosaurus from the most recent Cretaceous of Mongolia.”
“Extra primitive members of the clade like Falcarius, Beipiaosaurus, and Jianchangosaurus had comparatively smaller unguals in comparison with extra derived types, equivalent to Erliansaurus, Nothronychus, and particularly Therizinosaurus.”
“As herbivorous or omnivorous theropods with lengthy necks and small leaf-shaped enamel, the evolution of their uncommon fingers probably performed an necessary position within the feeding ecology of this clade.”
In response to the paleontologists, Duonychus tsogtbaatari is a medium-sized therizinosaur, with an estimated physique mass of roughly 260 kg.
The fossils of this dinosaur have been recovered from the Urlibe Khudak locality of the Bayanshiree Formation within the Gobi Desert, Ömnögovi province, southeastern Mongolia.
“The specimen consists of a partial skeleton, together with: six articulated dorsal vertebrae, six articulated sacral vertebrae with sacral ribs, the anterior-most caudal vertebra, some dorsal ribs, partial left scapula and coracoid, humeri, ulnae, radii, carpals, metacarpals, the left and proper manus, the suitable ilium, each pubes, and the proximal finish of the left ischium,” the researchers wrote.
Reconstructed skeleton and chosen parts of Duonychus tsogtbaatari. Picture credit score: Kobayashi et al., doi: 10.1016/j.isci.2025.112141.
Duonychus tsogtbaatari is completely different from different therizinosaurs in that the hand possesses solely two fingers, reasonably than three fingers.
“With respect to different therizinosaurs, this new species is exclusive in possessing a definitive didactyl (two-fingered) hand,” the scientists wrote.
“The specimen additionally novelly — amongst non-paravian theropods — preserves an entire, three-dimensional sheath representing the keratinous claw.”
The well-preserved specimen of Duonychus tsogtbaatari supplies perception into purposeful elements of its fingers.
“Based mostly on ventral curvature and angle of assault parameters of the claw, the preserved keratinous claw of Duonychus tsogtbaatari reveals features throughout the vary of scansorial (climbing), tenasorial (grappling) to amplectorial (greedy),” the authors wrote.
“Of those features, the herbivorous or omnivorous eating regimen and physique dimension of Duonychus tsogtbaatari, as in different therizinosaurids, would counsel an amplectorial utilization the place the claws serve to understand branches as in chameleons and a few mammals (e.g., southern tamandua, anteater), reasonably than to climb bushes (e.g., squirrels), or to understand, seize, or manipulate prey (e.g., birds of prey, felids).”
“Regardless of having solely two purposeful digits, Duonychus tsogtbaatari was probably an efficient grasper, contemplating the intense flexion on the ungual joint and the sturdy curvature of the keratinous claw, options unknown for different therizinosaurs.”
“Based mostly on the form of the ungual and the scale of the keratinous claw, Duonychus tsogtbaatari may have grasped branches or swaths of vegetation as much as roughly 10 cm in diameter, which is lower than the diameter of these grasped by Therizinosaurus, suggesting that Duonychus tsogtbaatari could have been extra selective in its foraging conduct.”
“The manus of Duonychus tsogtbaatari, with its sturdy ungual flexion and claw curvature, additional helps that the manus of derived therizinosaurs probably served in a rake or hook-and-pull operate to convey vegetation to the mouth throughout feeding as beforehand urged.”
“Though claws normally have a dominant operate, probably for hook-and-pull foraging in most derived therizinosaurs, these constructions may even have been utilized for different functions, equivalent to territoriality, protection, courtship, play, and so on.”
“Along with an sudden morphological variety of the therizinosaur manus (i.e., didactyly), Duonychus tsogtbaatari reveals a larger species richness of therizinosaurs in ecosystems of the Bayanshiree Formation than beforehand realized,” they concluded.
The crew’s paper was printed on March 25 within the journal iScience.
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Yoshitsugu Kobayashi et al. Didactyl therizinosaur with a preserved keratinous claw from the Late Cretaceous of Mongolia. iScience, printed on-line March 25, 2025; doi: 10.1016/j.isci.2025.112141
