School of Earth and Environmental Sciences, Seoul National University, Seoul, 08826, South Korea.
Hokkaido University Museum, Hokkaido University, Sapporo, Hokkaido, 060-0801, Japan.
Sci Rep. 2021 Nov 25;11(1):22928. doi: 10.1038/s41598-021-02273-4.
A new ankylosaurid dinosaur, Tarchia tumanovae sp. nov., has been recovered from the Upper Cretaceous Nemegt Formation of Mongolia. It includes a well-preserved skull, dorsal, sacral, caudal vertebrae, sixteen dorsal ribs, ilia, a partial ischium, free osteoderms, and a tail club. The squamosal horns of T. tumanovae are divided into two layers, the external dermal layer and the underlying squamosal horn proper. The irregular ventral margin of the base of the upper dermal layer may represent a resorption surface, suggesting that the squamosal horns of some ankylosaurids underwent extreme ontogenetic remodeling. Localized pathologies on the dorsosacral ribs and the tail provide evidence of agonistic behaviour. The tail club knob asymmetry of T. tumanovae resulted from restricted bone growth due to tail club strikes. Furthermore, T. tumanovae had an anteriorly protruded shovel-shaped beak, which is a morphological character of selective feeders. Ankylosaurid diets shifted from low-level bulk feeding to selective feeding during the Baruungoyot and the Nemegt "age" (middle Campanian-lower Maastrichtian). This ankylosaurid niche shifting might have been a response to habitat change and competition with other bulk-feeding herbivores.
一种新的甲龙类恐龙，Tarchia tumanovae sp. nov.，是从蒙古上白垩统的Nemegt 组中发现的。它包括一个保存完好的头骨、背骨、荐骨、尾骨、十六个背肋骨、坐骨、部分耻骨、游离的骨板和尾锤。T. tumanovae 的鳞骨角分为两层，外部真皮层和下面的鳞骨角本身。上真皮层基部不规则的腹侧边缘可能代表一个吸收面，这表明一些甲龙类的鳞骨角经历了极端的个体发育重塑。背荐肋骨和尾部的局部病变提供了竞争行为的证据。T. tumanovae 的尾锤球节不对称是由于尾锤撞击导致骨骼生长受限所致。此外，T. tumanovae 具有向前突出的铲形喙，这是选择性食草动物的形态特征。在 Baruungoyot 和 Nemegt“时代”（中坎潘期-下马斯特里赫特期），甲龙类的饮食从低水平的大量进食转变为选择性进食。这种甲龙类生态位的转变可能是对栖息地变化和与其他大量进食草食动物竞争的反应。
