Tagasi otsingusse
Weidner et al., 2023

Middle Cambrian agnostoids and trilobites from the Lower Allochthon, Swedish Caledonides

Weidner, T., Nielsen, A. T., Ebbestad, J. O. R.
DOI
DOI10.18261/9788215068022-2023
Aasta2023
AjakiriFossils and Strata
Köide68
Leheküljed1-121
Tüüpartikkel ajakirjas
Keelinglise
Id47547

Abstrakt

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 (Røyken, Øvre Eiker and Kongsberg) as well as those in the autochthonous and allochthonous areas to the north (Hov, Gran, Toten, Gjøvik, Ringsaker) and northeast (Elverum). Detailed profiles are provided for the classical areas of Slemmestad (Røyken), Risbekken (Toten), Gjøvik 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 New data is also presented from previously unpublished logged bore cores at Stavlum, near Brogger's classic locality of Krekling and farther west at Sandbakk, near Kongsberg.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 leve! 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 Robinson, 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 and 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 (Westergard in Holm & Westergard,1930); Peronopsis insignis (Wallerius, 1895 ); P. scutalis (HrcKs 1872); Diplorrhina depressa (Westergard,1946 ); D. cylindrica (Westergard, 1946); D. quadrata (Tullberg, 1880); Hypagnostus lingula (Gronwall, 1902); Tomagnostella exsculpta (Angelin, 1851); T sulcifera (Wallerius,1895); Ptychagnostus atavus (Tullberg, 1880); P. cassis Öpik, 1961; Goniagnostus scarabaeus Whitehouse, 1939; Lejopyge calva Robinson, 1964; L. elegens (Tullberg, 1880); Tomagnostus fissus (Lundgren in Linnarson, 1879); Glaberagnostus cicer (Tullberg, 1880); Lisogoragnostus confluentus (Rudolph, 1994); Phalagnostus scanicus (Tullberg, 1880); Condylopyge rex (Barrande, 1846) and Macannaia skybergi n. sp. Peronopsis fallax (Linnarsson, 1869); P. minor (Brogger, 1878); P. ferox (Tullberg, 1880) and Diplorrhina depressa (Westergard, 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 Strang collections. Among the new figured material are specimens chosen to show rare intraspecific variability, a feature of the agnostoids and important for the taxonomic classification followed in this work.

Viimati muudetud: 12.1.2025
KIKNATARCSARVTÜ Loodusmuuseumi geokogudEesti Loodusmuuseumi geoloogia osakond
Leheküljel leiduvad materjalid on enamasti kasutamiseks CC BY-SA litsensi alusel, kui pole teisiti määratud.
Portaal on osaks teadustaristust ning infosüsteemist SARV, majutab TalTech.
Open Book ikooni autor Icons8.