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Agnostid trilobites from the Lower Ordovician of southern Sweden

  • Per Ahlberg (a1)

Abstract

Agnostid trilobites are described from the Lower Ordovician (Oelandian Series) of Öland, Östergötland, Västergötland and Närke, southern Sweden. In addition, a few agnostids are described from the Ceratopyge Limestone (upper Tremadoc) of Scania (Skåne), the southernmost province of Sweden. 24 species (of which Galbagnostus nericiensis is new), assigned to four genera, are described or discussed. Species of Geragnostus and Arthrorhachis dominate numerically. Also recorded locally are species of Galbagnostus and Leiagnostus. Most species have a markedly restricted vertical distribution, and many species appear to have a sufficiently short range to be of value in stage- and zone-level correlation. Agnostids are represented almost throughout the Lower Ordovician of southern Sweden, but they have not been recorded from the Tremadocian “Dictyonema” and Ceratopyge Shales, nor from the upper Holen Limestone (upper Kundan Stage). In the Ordovician of Baltoscandia, agnostids are largely restricted to the Central Baltoscandian Confacies Belt; they are very rare or absent in the adjacent belts to the east and in the graptolitic shales of the Scanian Confacies Belt.

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