科研之友
微信
新浪微博
Facebook
分享链接
摘要
New and accurately located material of agnostoid and eodiscoid trilobites has been collected from Middle Cambrian rocks exposed in the Oslo Region, Norway. These include the classical areas South and west of Oslo (Royken, Ovre Eiker and Kongsberg) as well as those in the autochthonous and allochthonous areas to the north (Hov, Gran, Toten, Gjovik, Ringsaker) and northeast (Elverum). Detailed profiles are provided for the classical areas of Slemmestad (Royken), Risbekken (Toten), Gjovik and Ringsaker. New data is also presented from previously unpublished logged bore cores at Stavlum, near BROGGER'S classic locality of Krekling and farther west at Sandbakk, near Kongsberg. The proposed new (international) global agnostoid zonation for the Middle Cambrian can be applied to the Norwegian succession and following Swedish colleagues, the Hypagnostus parvifrons Zone is now included in an extended Ptychagnostus atavus Zone and the Solenopleura brachymetopa Zone is included in the Lejopyge laevigata Zone. An upper subdivision of the latter into the Proagnostus bulbus Zone in China cannot be recognised in Scandinavia. No distinct limestone beds indicating low-stand sea level periods can be recognised with certainty, but at Slemmestad and Ringstrand, Ringsaker, a conglomerate at the base of the Ptychagnostus gibbus Zone may be equivalent to the Forsemolla Limestone Bed defined from SE Scania, Sweden. Higher in the section at Ringstrand a 15 cm thick bed crowded with hyolithids may be equivalent to the Hyolithes Limestone Bed in S.E. Scania and is followed by a 20 cm thick conglomerate containing fossils indicative of the Lejopyge laevigata and Goniagnostus nathorsti Zones. Lejopyge calva ROBISON, 1964, previously described from the L. laevigata Zone of Utah (USA) is very common in the conglomerate at Ringstrand which is approximately equivalent to the Exporrecta Conglomerate in Vastergotland, Sweden. An extended discussion is provided for the families Diplagnostidae, Peronopsidae and Ptychagnostidae. 22 genera arid 48 species of agnostoids and 2 genera and species of eodiscoids are described. Species recognised in Norway for the first time are Agnostus neglectus WESTERGARD, 1946; Clavagnostus repandus (WFSTERGARD in HOLM & WESTERGARD 1930); Peronopsis insignis (WALLERIUS 1895); P. scutalis (HICKS 1872); Diplorrhina depressa (WESTERGARD 1946); D. cylindrica (WESTERGARD 1946); D. quadrata (TULLBERG, 1880); Hypagnostus lingula (GRONWALI, 1902); Tomagnostella exsculpta (ANGELIN, 1851); T sulcifera (WALLERIUS 1895); Ptychagnostus atavus (TULLBERG 1880); P. cassis OPIK, 1961; Goniagnostus scarabaeus WHITEHOUSE, 1939; Lejopyge calva ROBISON, 1964; L. elegens (TULLBERG 1880); Tomagnostus fissus (LUNDGREN in LINNARSSON 1879); Glaberagnostus cicer (TULLBERG 1880); Lisogoragnostus confluentus (RUDOLPH 1994); Phalagnostus scanicus (TULLBERG 1880); Condylopyge rex (BARRANDE 1846) arid Macannaia skybergi n.sp. Peronopsis fallax (LINNARSSON 1869); P. minor (BROGGER 1878); P. ferox (TULLBERG 1880) and Diplorrhina depressa (WFSTERGARD 1946), formerly subspecies, are afforded specific rank. Norwegian material of Diplagnostus planicauda (ANGELIN 1851); Peronopsis minor (BROGGER 1878) and Eodiscus punctatus (SALTER 1864) is figured for the first time together with new figures of type and additional material from the BROGGER and STRAND collections. Among the new figured material are specimens chosen to show rare intraspecific variability, a feature of the agnostoids arid important for the taxonomic classification followed in this work.
- 出版日期2008-11
- 单位中国地质博物馆
