Shamosaurus is an extinct genus of herbivorous basal ankylosaurid ankylosaur from Early Cretaceous (Aptian to Albian stage) deposits of Höövör, Mongolia.

In 1977, a Soviet-Mongolian expedition discovered the skeleton of an unknown ankylosaurian at the Hamrin-Us site in Dornogovi Province.

The specific name means "protected by a shield" in Latin, a reference to the body armour.

In 2010, Gregory S. Paul estimated its body length at 5 metres (16 ft), its weight at 2 tonnes (2.2 short tons).

[2] Shamosaurus scutatus shares many cranial similarities with Gobisaurus domoculus, including a rounded squamosal, large elliptical orbital fenestrae (oval eye sockets) and oval external nares (nostrils), a deltoid dorsal profile with a narrow rostrum (the snout is tongue-shaped and narrow in top view), quadratojugal protuberances (cheek horns), and caudolaterally directed paroccipital processes (extensions of the rear skull obliquely pointing to behind and sideways).

Saichania Zaraapelta Tarchia Tsagantegia Talarurus Nodocephalosaurus Ziapelta Euoplocephalus Ankylosaurus Anodontosaurus Scolosaurus Zuul Dyoplosaurus In phylogenetic analyses by Xing et al. (2024), Shamosaurus is recovered as a member of Shamosaurinae or as an ankylosaurid, more derived than Gobisaurus.

Below are two simplified cladograms from that study:[7] Cedarpelta Chuanqilong Liaoningosaurus Gobisaurus Shamosaurus Ankylosaurinae