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描述产自浙江常山205国道剖面上奥陶统砚瓦山组的牙形刺,主要有Baltoniodus alobatus,B.variabilis,Periodon aculeatus,Dapsilodus viruensis,Scabbardella altipes和Panderodus gracilis等,可归入Baltoniodus alobatus带。浙赣地区奥陶系砚瓦山组自建立以来都被归入瀚江期,并与宝塔组对比。本文根据当前的发现并结合以前报道的砚瓦山组牙形刺化石,认为砚瓦山组自下而上可识别出Pygodus anserinus,Baltoniodus alobatus和Hamarodus brevirameus(=Hamarodus europaeus)等带,其时代应归为桑比早期至凯迪早期,并可与华南扬子区的庙坡组大部(或大田坝组)至宝塔组对比。其中,Pygodus anserinus带和Baltoniodus alobatus带见于浙江常山、江山地区,Hamarodus brevirameus带则见于江西武宁。在常山黄泥塘金钉子剖面,砚瓦山组底部为Pygodus anserinus带;在常山205国道剖面则见Baltoniodus alobatus带;但在江西武宁地区,砚瓦山组从底部起,几乎全都归为Hamarodus brevirameus带。因而,砚瓦山组在江西武宁与浙江常山等地之底界并不一致,有明显的穿时现象。本文牙形刺生物地层研究还表明,晚奥陶世古滕贝格的δ13 C的正偏移事件(GICE)在常山地区的起始时间不会早于B.alobatus带。
The description of conodonts from the Upper Ordovician Yan’anshan Formation in Section 205 of Changshan, Zhejiang Province are Baltoniodus alobatus, B. variabilis, Periodon aculeatus, Dapsilodus viruensis, Scabbardella altipes and Panderodus gracilis, which can be classified as Baltoniodus alobatus. The Ordovician Yan Wenshan Formation in the Zhejiang-Jiangxi region has been included in the Hanjiang period since its establishment and has been compared with the Pagoda Formation. Based on the current findings and combining with the previously reported Ostwald fossils of the Yan Wanshan Formation, it is concluded that the Yanwashan Formation can identify the zones of Pygodus anserinus, Baltoniodus alobatus and Hamarodus brevirameus (= Hamarodus europaeus) from the bottom up, It was classified as the early period of Sambi to early Kaidi and compared with that of most of the Miaopu Formation (or Da Tianba) in the Yangtze Region of South China. Among them, the Pygodus anserinus belt and the Baltoniodus alobatus belt are found in Changshan, Jiangshan region of Zhejiang Province, while the Hamarodus brevirameus belt is found in Wuning, Jiangxi Province. In the golden nail section of Changchun Huangnitang, the bottom of the Yanwashan Formation is the Pygodus anserinus belt, while the Baltoniodus alobatus belt is found in the section of the Changshan 205 National Road; however, in the Wuning area of Jiangxi Province, the Yan Wanshan Formation is almost all classified as Hamarodus brevirameus band. Thus, Yan Wanshan group in Wuning, Jiangxi and Zhejiang Changshan and other places at the bottom are not the same, there is a clear wear phenomenon. In this paper, the research on the biosphere of conodont also shows that the onset of δ13C positive offset event (GICE) of Gutenberg in the Late Ordovician will not be earlier than that of the B. alobatus in Changshan area.