华南贵州早奥陶世红花园组的镰箭类牙形刺(英文)

DREPANOISTODONTID CONODONTS FROM THE EARLY ORDOVICIAN HONGHUAYUAN FORMATION OF GUIZHOU, SOUTH CHINA

本文描述了产自华南贵州下奥陶统红花园组(桐梓红花园标准剖面,沿河甘溪剖面和贵阳黄花冲剖面)的四个镰箭类牙形刺种:Drepanoistodus sp.cf.nowlani,Paltodus sp.cf.P.subaequalis,Paltodus sp.A和Paroisto-dus sp.。D.sp.cf.nowlani为红花园组常见种,但另三种则相对稀少。在红花园组标准剖面,Paltodus sp.cf.P.subaequalis最低出现于该组底部,证实此层位为晚特马豆克期。文中详细图示了产于瑞典下奥陶统的两个带化石种:Paltodus deltifer和Paroistodus proteus,以及瑞典镰箭刺属的三个常见种:Drepanoistodus forceps,D.basiovalis和D.sp.cf.D.suberectus。通过与瑞典材料的详细对比,我们认为华南以前关于P.proteus和P.deltifer两种的记述多有误,须重新厘定。

Four drepanoistodontid species, Drepanoistodus sp. cf. D. nowlani, Paltodus sp. cf. P. subaequalis, Paltodus sp. A and Paroistodus sp. are described and illustrated from the Lower Ordovician Honghuayuan Formation in Guizhou, South China. Drepanoistodus sp. cf. D. nowlani is abundant throughout the formation whereas the other three species occur rarely. Presence of Paltodus sp. cf. P. subaequalis at the base of the Honghuayuan Formation at its type locality indicates a late Tremadocian age for this level. Specimens from Sweden of the two Lower Ordovician index species Paltodus deltifer and Paroistodus proteus, as well as three species of Drepanoistodus （D. forceps, D. basiovalis and D. sp. cf. D. suberectus）, are also illustrated. Comparison with the Swedish material reveals that previously reported occurrences of P. deltifer and P. proteus in South China were either mis-identified or based on ambiguous data.