2025-03-26 北海道大学
<関連情報>
- https://www.hokudai.ac.jp/news/2025/03/2-68.html
- https://www.hokudai.ac.jp/news/pdf/250326_pr.pdf
- https://www.cell.com/iscience/fulltext/S2589-0042(25)00401-8
モンゴル白亜紀後期から出土した角質の鉤爪を持つディダクティル・テリジノサウルス Didactyl therizinosaur with a preserved keratinous claw from the Late Cretaceous of Mongolia
Yoshitsugu Kobayashi∙ Darla K. Zelenitsky ∙ Anthony R. Fiorillo ∙ Tsogtbaatar Chinzorig
iScience Published:March 25, 2025
DOI:https://doi.org/10.1016/j.isci.2025.112141
Graphical abstract
Highlights
- Duonychus tsogtbaatari is described as another therizinosaur from Mongolia
- It is a didactyl therizinosaur, possessing only two manual digits
- A keratinous sheath on digit I provides rare insight into theropod claw structure
- Duonychus reveals convergent digit III loss in at least five theropod clades
Summary
Therizinosaurs were a group of herbivorous/omnivorous theropod dinosaurs that lived in Asia and North America during the Cretaceous Period. These theropods are notable for their three-fingered hands sporting large claw-like unguals. Here, we describe a new and unusual species of the therizinosaurid Duonychus tsogtbaatari, recovered from the lower Upper Cretaceous Bayanshiree Formation of the Gobi Desert of Mongolia. This species is different from other therizinosaurs in that the hand possesses only two fingers, rather than three fingers, the typical condition for Avetheropoda, providing further insight into forelimb/hand reduction among theropods. Phylogenetically, Duonychus reveals a broader but still limited appearance of didactyly among avetheropodans. The manual ungual of Duonychus tsogtbaatari also preserves a nearly complete three-dimensional structure covering the ungual of the left manual digit I, which represents a keratinous manual claw. The strong curvature of this large claw and high ungual flexion indicate that Duonychus was likely amplectorial (grasping) and an effective grasper of vegetation, despite having only two functional fingers.
