Amtosaurus
Named after Amtgai, the Mongolian type locality, plus Greek sauros ('lizard')
Amtosaurus is a genus of ornithischian dinosaur based on a fragmentary skull collected from the Late Cretaceous (Cenomanian to Turonian) Bayanshiree Formation of Mongolia and originally believed to represent an ankylosaurid. Hadrosaurid affinities have also been suggested. However, according to Parish and Barrett, this specimen is too fragmentary to be reliably classified beyond an indeterminate ornithischian. A second species assigned to the genus, A. archibaldi, has become the basis of a valid ankylosaurid taxon, Bissektipelta.
Under dispute
Amtosaurus is a nomen dubium based on a braincase originally referred to Ankylosauria; later assessment could not confirm even an ankylosaurian identity and delegated it to Ornithischia indeterminate (Parish and Barrett, 2004; Jones, 2026).
Species
Amtosaurus magnus Kurzanov & Tumanova, 1978 Nomen dubium
Type species
From Latin 'magnus' meaning 'large/great'.
- Holotype
- PIN 3780/2 , Paleontological Institute, Russian Academy of Sciences
- Horizon
- Bayanshiree Formation, Cenomanian–Turonian, Late Cretaceous , 100.5–89.8 million years ago
- Locality
- Amtgai, Ömnögovi, Mongolia
References
- Kurzanov, S. M.; Tumanova, T. A. (1978). The structure of the endocranium in some Mongolian ankylosaurs. Paleontological Journal 1978(3): 369-374. kurzanov1978a
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Parish, J. C.; Barrett, P. M. (2004). A reappraisal of the ornithischian dinosaur Amtosaurus magnus Kurzanov and Tumanova 1978, with comments on the status of A. archibaldi Averianov 2002. Canadian Journal of Earth Sciences 41(3): 299-306. Canadian Science Publishing. doi:10.1139/e03-101
Assessed the Amtosaurus braincase and could not confirm an ankylosaurian identity.
parish2004a -
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Treats Amtosaurus as a nomen dubium, an indeterminate ornithischian.
jones2026a