黔南独山地区泥盆系法门阶–石炭系杜内阶革老河组 和汤粑沟组长身贝类新认知

本文描述了在黔南独山县其林寨剖面和黎家寨剖面上泥盆统革老河组和下石炭统汤粑沟组中发现的长身贝类化石共8属10种(含未定种)。其中, 在革老河组中发现有3属4种: Productella? sp.、Yanguania dushanensis、Xinshaoproductus xinshaoensis和X. quadrata; 汤粑沟组中有8属9种: Productella? sp.、Hunanoproductus hunanensis、Spinocarinifera qilinzhaiensis sp. nov.、Yanguania dushanensis、Y.? sp.、Xinshaoproductus xinshaoensis、Tomiproductus sp.、Ozora? sp.和Ericiatia kiangsuensis。总体而言, 革老河组和汤粑沟组中的长身贝类在组成上主要以Productoidea超科中Productidae科的分子为主, Productellidae科和Echinoconchoidea超科中Sentosiidae科的分子各有1种。本文记述的Hunanoproductus和Xinshaoproductus系在黔南地区首次发现, 并且Xinshaoproductus在黔南地区的首现层位低于湘中地区。常见于欧亚地区的中泥盆统吉维特阶至上泥盆统弗拉斯阶及湘中地区上泥盆统的Productella属, 在黔南地区上延到了下石炭统的汤耙沟组中, 为该属最晚的化石记录。Spinocarinifera和Tomiproductus是欧亚、北美、西澳和北非等地杜内阶或杜内阶-维宪阶中的常见分子, 汤粑沟组中发现的S. qilinzhaiensis sp. nov.则是目前已知该属在华南地区的代表。该种以近方圆形的轮廓、铰合线短、耳翼小、放射状壳线连续但微弱为特征, 区别于该属的其他种。而Tomiproductus在华南地区见于湘中刘家塘组的上部和下扬子地区的金陵组。Ozora属于美国密苏里地区维宪阶下部的代表分子, 亦见于墨西哥南部的下石炭统。如果鉴定无误, 黔南地区的发现则有可能代表了该属最早的化石记录。革老河组的长身贝类组成属种单调, 以Yanguania、Xinshaoproductus属等地方性分子为特征; 随着杜内期的海侵, 汤耙沟组中的长身贝类组成与湘中地区的更为相近, 生物多样性显著增加, 既继承了革老河组中的地方性分子, 同时在属级分类单元中也出现了一些在欧美、澳大利亚等地区的类型, 如Spinocarinifera、Tomiproductus和Ozora属。反映了从杜内期开始的海侵, 使华南地区的腕足动物群与欧美地区同时期的腕足动物群之间开始发生较为密切的生物地理区系联系。

Productoid brachiopods from the Devonian (Famennian) Gelaohe and Car-boniferous (Tournaisian) Tangbagou formations of the Dushan area of Gui-zhou, China

Ten species belonging to eight genera of productoid brachiopods (including indeterminate species) from the Upper Devonian Gelaohe and Lower Carboniferous Tangbagou formations in the Dushan area of Guizhou Province were described in this paper. The Gelaohe Formation contains Productella? sp., Yanguania dushanensis, Xinshaoproductus xinshaoensis and X. quadrata. Apart from sharing Productella? sp., Yanguania dushanensis, and Xinshaoproductus xinshaoensis with the Gelaohe Formation, the Tangbagou Formation also yields Hunanoproductus hunanensis, Spinocarinifera qilinzhaiensis sp. nov., Yanguania? sp., Tomiproductus sp., Ozora? sp., and Ericiatia kiangsuensis. The productoid brachiopods of these two formations are dominated by elements of the family Productidae (super-family Productoidea) in composition, and have only one representative of the family Productellidae and one of the family Sentosiidae (super-family Echinoconchoidea). Hunano-productus and Xinshaoproductus are first recognized in southern Guizhou in this study, and the former is preserved in a lower horizon than that in central Hunan Province. The Lower Carboniferous Tangbagou Formation in southern Guizhou witnesses the latest occurrence of Productella, which was previously recorded from Givetian to Frasnian of Eurasia and Up-per Devonian of Central Hunan. Spinocarinifera are widely recorded from Tournaisian or Tournaisian to Visean of Eurasia, North America, western Australia, and northern Africa. The new species S. qilinzhaiensis sp. nov. established herein, charac-terized by round quadrate outline, relatively short hinge line, small and flat ears, and weak but complete ribbings, is the only representative of the genera in South China. The spatial-temporal distribution of Tomiproductus generally accords with that of Spinocarinifera abroad, while in South China, Tomiproductus was recorded in the Liujiatang Formation of central Hunan and the Jinling Formation of Lower Yangtze area. The Ozora in southern Guizhou, if classified correctly, is the lowermost occurrence of the genus, lower than the records in the lower Visean of Missouri, US, and the Lower Carboniferous of South Mexico. The productids in southern Guizhou have a relatively low biodiversity in the Upper Devonian Gelaohe Formation, mainly comprising endemic genera such as Yanguania and Xinshaoproductus. The composition of productids in southern Guizhou was obviously affected by the Tournaisian transgression. Several cosmopolitan genera, including Spinocarinifera, Tomiproductus, Ozora, appeared in the Lower Carboniferous Tangbagou Formation this area, accompanied by the long-endurance endemic genera from the Gelaohe Formation, and thus obviously increased the biodiversity. Meanwhile, the biogeographical affinity among southern Guizhou, central Hunan, and Euramerica became closer due to the Tournaisian transgression in southern China.