Xiangshuiosteus in Yunnan

Xiangshuiosteus wui is a brachythoracid arthrodire placoderm from the Late Emsian epoch of Wuding, Yunnan. It has recently been reassessed as a dunkleosteid.

Specimen and taxonomy

X. wui is known from a flattened, “Buddhist cap” shaped skull roof.[2] The skull roof is strongly reminiscent of those of coccosteids, but also has anatomical features otherwise diagnostic of buchanosteids.[2] This mix of anatomy lead its describer, Wang Junqing, to suggest that X. wui is the sister taxon of Coccosteidae, and represents a transitional form between Coccosteidae and Buchanosteidae.[2] A reappraisal of Kiangyousteus and several other eubrachythoracid arthrodire genera by You-An Zhu and Min Zhu lead to the conclusion that X. wui not only does not represent a transitional form between coccosteids and buchanosteids, but is actually a dunkleosteid closely related to the Gogo Reef Eastmanosteus calliaspis (which is, in turn, implied to be not of the genus Eastmanosteus).[3]


The generic name literally translates as “Chinese: 香水; literally: ‘perfume'(Pinyin:Xiāngshuǐ) + bone,” but actually refers to Xiangshui Valley,[note 1] the district[2] in Wuding County where the holotype was found.[2] The specific name honors Wu Baosheng, the gentleman who provided the holotype to Wang Junqing, the species’ describer.[2]

See also

  • Jiuchengia a coccosteid found in the same formation.


  1. ^ Not to be confused with Xiangshui County (Chinese: 响水县; literally: ‘noisy water’)(Pinyin:Xiǎng shuǐ) in Jiangsu province