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Temporal range: Late Emsian[1]
Xiangshuiosteus wui.jpg
Artist's reconstruction
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Class: Placodermi
Order: Arthrodira
Suborder: Brachythoraci
Infraorder: Pachyosteomorphi
Superfamily: Dunkleosteoidea
Family: Dunkleosteidae
Genus: Xiangshuiosteus
Species: X. wui
Binomial name
Xiangshuiosteus wui
Wang 1992[2]

Xiangshuiosteus wui is a brachythoracid arthrodire placoderm from the Late Emsian epoch of Wuding, Yunnan. It has recently been reassessed as a dunkleosteid.[3]

Specimen and Taxonomy[edit]

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[edit]


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


  1. ^ Wang Junqing & Min, Zhu (1995). "Age of the Jiucheng Formation of Wuding,Yunnan". Institute of Vertebrate Palaeontology and Palaeoanthropology, Academia Sinica, Beijing. Retrieved 2013-05-20. 
  2. ^ a b c d e f g Wang Junqing (April 1992). "NEW DISCOVERY OF EARLY MIDDLE DEVONIAN BRACHY-THORACID (PLACODERM FISH) FROM WUDING REGION OF YUNNAN". Vertebrata PalAsiatica. 30 (2): 111–119. 
  3. ^ a b Zhu, You‐An, and Min Zhu. "A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci." Zoological Journal of the Linnean Society169.4 (2013): 798-819.