Early Devonian fish material from Posongchong Formation of Guangnan, Yunnan, China

doi:10.19615/j.cnki.2096-9899.260206

Abstract

Abstract:

New findings of early vertebrates, including placoderms, sarcopterygians, and the galeaspids Sanqiaspis rostrata, Macrothyraspis longicornis, Gantarostraspis gengi, Wenshanaspis sp., are described from Posongchong Formation (Pragian, Lower Devonian) in Zhujie, Guangnan County, Wenshan Prefecture, Yunnan, China. The new specimen of Macrothyraspis longicornis exhibits the ventral side of its headshield, revealing a large branchial chamber encompassed by a very narrow ventral rim. The material of Yunnanolepidoidei and Petalichthyida represents the first fossil record of placoderms from Wenshan Prefecture, southwestern Yunnan. These new findings enrich the fish diversity of the Pragian Xujiachong Vertebrate Assemblage and provide additional paleoichthyological data for the biostratigraphic correlation between Posongchong Formation and its coeval strata in southwestern China and northern Vietnam.

Key words: Guangnan, Wenshan, Yunnan, Posongchong Formation, Early Devonian, Pragian, galeaspids, placoderms

摘要：

记述了云南省文山州广南县珠街镇早泥盆世布拉格期坡松冲组发现的早期脊椎动物新材料，包括盾皮鱼类、肉鳍鱼类以及长吻三岐鱼(Sanqiaspis rostrata)、长角大窗鱼(Macrothyraspis longicornis)、鸭吻鱼(不定种) (Gantarostraspis sp. indet.)、文山鱼(未定种) (Wenshanaspis sp.)等多种盔甲鱼类。长角大窗鱼的新标本展示了其头甲的腹面，呈现出被狭窄腹环包围的口鳃腔。云南鱼目(Yunnanolepidoidei)和瓣甲鱼目(Petalichthyida)的新材料代表了滇西南文山地区盾皮鱼类化石的首次记录。这些新发现丰富了徐家冲脊椎动物群的鱼类多样性，并为坡松冲组与中国西南部和越南北部同期地层之间的生物地层对比提供了更多的古鱼类学资料。

关键词: 云南文山广南, 坡松冲组, 早泥盆世, 布拉格期, 盔甲鱼类, 盾皮鱼类

CLC Number:

XIAN Zu-Min, MO Xiong, GUAN Qi, ZHAO Ying-Tian, XUE Qin-Yuan, LI Qiang, LIU Jun-Ping, ZHU Min. Early Devonian fish material from Posongchong Formation of Guangnan, Yunnan, China. Vertebrata Palasiatica, 2026, 64(2): 151-166.

鲜祖敏, 莫雄, 关奇, 赵应天, 薛钦元, 李强, 刘军平, 朱敏. 2026, 64(2): 151-166, 云南广南早泥盆世坡松冲组鱼类化石新材料. 古脊椎动物学报.

Figures/Tables 6

Fig. 1 Geological setting of the fossil fish sites in Wenshan Prefecture, Yunnan Province A. locality map of the fossil fish sites; B. fish-bearing lithological column in Zhujie Township, Guangnan County, Wenshan Prefecture, Yunnan Province; C. geological map in Zhujie, showing the fossil fish locality Abbreviations: ∈2l. Longha Formation; ∈3b. Bocaitian Formation; ∈3t. Tangjiaba Formation; ∈3x. Xiechang Formation; C2w. Weining Formation; D1b. Bajiaoqing Formation; D1c. Cuifengshan Formation; D1p. Pojiao Formation; D1ps. Posongchong Formation; D2g. Gumu Formation; O1f. Fenxiang Formation; O1hn. Honghuayuan Formation; O1l. Laozhai Formation; O1ls. Lengshuigou Formation; O1m. Meitan Formation; O1n. Nanjinguan Formation

Fig. 2 Photograph (A) and interpretative drawing (B) of Sanqiaspis rostrata (YDDY10002) from Posongchong Formation, Guangnan County, Wenshan Prefecture, Yunnan in dorsal views scale bars = 1 cm

Fig. 3 Photograph (A) and interpretative drawing (B) of Macrothyraspis longicornis (IVPP V34296) from Posongchong Formation, Guangnan County, Wenshan Prefecture, Yunnan in ventral views Scale bars = 1 cm

Fig. 4 Gantarostraspis gengi (A, B) and Wenshanaspis sp. (C-E) from Posongchong Formation, Guangnan County, Wenshan Prefecture, Yunnan A, B. photographs of incomplete rostral process of G. gengi, IVPP V34297a, b; C-E. photograph (C) and interpretative drawings (D, E) of an incomplete headshield of Wenshanaspis sp., YDDY10001b, in dorsal (C, D) and ventral (E) views. Scale bars = 1 cm

Fig. 5 Photographs of new specimens of placoderms and sarcopterygians from Posongchong Formation, Guangnan County, Wenshan Prefecture, Yunnan A, B. an anterior median dorsal plate of Yunnanolepidoidei indet. (YDDY10003) in dorsal (A) and visceral (B) views; C, D. an incomplete ventral wall of trunk-shield of Petalichthyida indet. (YDDY10004a, b) in visceral (C) and internal (D) views; E, F. Sarcopterygian scales, IVPP V34298 (E) and V34299 (F) Scale bars = 1 cm

Fig. 6 Close-up of the paleogeographic map of the South China Block showing the major fish and plant fossil localities around the South China Sea (modified from Xue et al., 2018) Abbreviations: a. Posongchong Formation at Zhujie, Wenshan, Southeast Yunnan; b. Posongchong Formation at Zhaotong, Northeast Yunnan; c. Xujiachong Formation at Qujing, East Yunnan; d. Posongchong Formation at Zhichang, Wenshan, Southeast Yunnan; e. Khao Loc Formation at Tong Vai Valley, North Vietnam; f. Si Ka and Bac Bun formations at Dong Van, Ha Giang, North Vietnam; g. Lianhuashan and Nahkaoling formations at Chongzuo, Guangxi; h. Lianhuashan and Nahkaoling formations at Nanning, Guangxi; i. Posongchong Formation at Wuding, Northeast Yunnan

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