Maleevus

Between 1946 and 1949, Soviet-Mongolian expeditions uncovered fossils at Shiregin Gashun. In 1952, Soviet palaeontologist Evgenii Aleksandrovich Maleev named some ankylosaurian bone fragments as a new species of Syrmosaurus: Syrmosaurus disparoserratus. The specific name refers to the unequal serrations on the teeth.[1]

The holotype, PIN 554/I, was found in a layer of the Bayan Shireh Formation dating from the Cenomanian-Santonian. It consists of two upper jawbones, left and right maxillae. Maleev erroneously assumed these represented the lower jaws. Referred was specimen PIN 554/2-1, the rear of the skull of another individual.[1]

In 1977, Teresa Maryańska noted a similarity with another Mongolian ankylosaur, Talarurus, in that both taxa have separate openings for the ninth to twelfth cerebral nerve; she therefore renamed the species as Talarurus disparoserratus.[2] Having determined that Syrmosaurus is a junior synonym of Pinacosaurus, Soviet palaeontologist Tatyana Tumanova named the material as a new genus Maleevus in honor of Maleev in 1987.[3] The type species remains Syrmosaurus disparoserratus, the combinatio nova is Maleevus disparoserratus.[4] In 1991, George Olshevsky named the species as a Pinacosaurus disparoserratus.[5] In 2014, Victoria Megan Arbour determined that the rear skull was not different from that of many other ankylosaurids and that the single distinguishing trait of the teeth, a zigzag pattern on the cingulum, was shared with Pinacosaurus. She concluded that Maleevus was a nomen dubium.[6]

The preserved maxillae have length of about twelve centimetres.[1] This indicates that Maleevus was a medium-sized ankylosaur of around 6 metres (20 ft). The height and weight of Maleevus is unknown due to the lack of known remains. (size estimates based on the related Talarurus).

Syrmosaurus disparoserratus was by Maleev placed in the Syrmosauridae.[1] Today Maleevus is seen as a member of the Ankylosauridae.

• Timeline of ankylosaur research