The Datai fossil material was discovered in 2016, in sediments of the Zhoutian Formation in Mazhou, Huichang County, Jiangxi Province, China. The fossils were then obtained by the Yingliang Stone Natural History Museum two years later, where they are currently stored. The two known specimens—representing different ages of immaturity—were found articulated and in association.[1]
The paratype specimen, YLSNHM 01003, also includes a skull, in addition to all of the cervical vertebrae, five dorsal vertebrae, incomplete pectoral girdles, the left elbow region (distal humerus and proximal radius and ulna), and osteoderms.[1]
In 2024, Xing et al.describedDatai yingliangis as a new genus and species of ankylosaurine dinosaur based on these fossil remains. The generic name, 'Datai' (IPA:[ˌdɑˈtʰaɪ̯]), is a composite of the last character of the words 'tongda' (IPA:[ˌtɒŋˈdɑ]) (to understand/to be sensible) and 'antai' (IPA:[ˌɑnˈtʰaɪ̯]) (stable) in Chinese Pinyin. The specific name, 'yingliangis' (IPA:[ˌjɪŋˈlɪɑŋɪs]), is in recognition of the Yingliang Group.[1]
Xing Lida pointed out that in the past, ankylosaurian phylogenies had little stability with many clades tending to collapse into polytomies. In the study he used the traits of Datai to improve the resolution. For their phylogenetic analysis, Xing et al. (2024) tested two character matrices. The first was based on the findings of Zheng et al. (2018) with fourteen poorly preserved taxa being deleted or "pruned" by Xing, and the second was based on the findings of Raven et al. (2023) with 34-taxon deletion. The first tree recovers Datai as a basal ankylosaurine, while the second recovers it as a sister taxon to the two Pinacosaurus species.[1]
Both trees are reproduced below excluding the outgroups for improved readability:
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