[2] The holotype, IVPP V5542 was found on a cliff southwest of Laiyang, Shandong Province, near Hongtuyan train station.

[3] The remains were named and described by Dong Zhiming in 1978 as belonging to the new genus and species Micropachycephalosaurus hongtuyanensis,[3] which he incorrectly figured was discovered in the Wangshi Formation.

[3][4] Dong (1978) briefly described, but did not figure, a parietal and squamosal that also supposedly belonged to the holotype,[3] but Butler & Zhao (2009) were unable to locate them.

The one piece of evidence that could provide this link, the supposedly thickened skull roof, was missing from the fossil collection the scientists examined, and so could not be used to support or refute its original classification.

As the Hongtuya is directly older than the Jiangjunding, it was identified that Tanius sinensis, a contemporary of Micropachycephalosaurus, lived in the latest Campanian to earliest Maastrichtian by Borinder in 2015.