Cephalic shield of Dunyu longiforus gen. et sp. nov. ( holotype IVPP V 17681) from the Ludlow (Silurian) Kuanti Formation of Qujing, Yunnan, southwestern China. A. dorsal view; B. ventral view; C. close-up view of the left corner; D. close-up view to show the regional variation of polygonal tubercles, and minute spines on the inner surface of the dermal rim encircling the median dorsal opening; E. illustrative drawing in dorsal view. (Image by ZHU Min)