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Silurian trilobites from Scandinavia

Helbert, Gregory James

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Gregory James Helbert


Trilobites of the family Lichidae are described from the Silurian of Gotland, Sweden. Nineteen species (fourteen of which are named, two new) are assigned to Acanthopyge, Choneiliobarges, Craspedarges, Dicranopeltis, Lichas, Platylichas and Pseudotupolichas. Trimerolichas Phleger, 1936 is considered to be a junior subjective synonym of Lichas Dalman, 1827. L. gotlandicus Angelin, 1854 and L. palifer Lindstrom, 1885 are respectively considered to be subjective synonyms of Lichas latifrons Angelin, 1854 and Lichas araneus Lindstrom, 1885. L. triquetrus Lindstrom, 1885 is considered to be a juniour subjective synonym of Dicranopeltis salteri (Fletcher, 1850). Named species from Gotland also occur in the East Baltic, Scotland, England and Wales. One unnamed species which possibly belongs to Dicranogmus is considered identical to one from the Wenlock of Greenland. The Lichidae of Gotland also show close affinities to species from Ejin Qui Province in China and the Chicago area of the U.S.A. Trilobites belonging to the families Aulacopleuridae, Brachymetopidae, Calymenidae, Cheiruridae, Encrinuridae, Illaenidae, Lichidae, Odontopleuridae, Phacopidae, Proetidae and Styginidae from the Silurian of southern Norway are described. Fifty-seven forms (forty-one named, fourteen of which are new and sixteen are under open nomenclature) are assigned to AoePnaspis, Apotinupus, Bumastus, Calymene, Choneliobapges, Cyphoppoetus, Diaoalymene, Diopanopeltis, Dudleyaspis, Eccaipos gen. nov., Ekwanoscutellum, Encrinupus, Eophacops, Hadromepos, Harpidella, Hedstroemia, Leonaspis, Lichas, Opsypharus, Platylichas, Proetus, Pseudotupolichas, and Warburgella. Illaenus rotundus Kiaer, 1908, Illaenus sculptus Kiaer, 1908 and Illaenus thomsoni Salter, 1867 are considered junior subjective synonyms of Stenopapeia glaber (Kjerulf, 1865). Bumastus? phrix Lane & Thomas, 1978 and B. depressus Kiaer, 1908 are respectively considered to be junior subjective synonyms of Bumastus? inf1atus (Kiaer, 1908) and Opsypharus maccallumi (Salter, 1867). Named species from the Silurian of southern Norway occur also in Canada, the East Baltic, England, Gotland, Sweden and Wales. Similar trilobite associations to those found in the Silurian of southern Norway have been recorded from the U.K. and the East Baltic. These associations are consistent with a shallow water environment, as shown by work on other fossil groups and by sedimentological evidence. Abundant faunas from the Llandovery and early Wenlock are dominated by associations of Acepnaspis with species of Encpinupus and "illaenimorph" trilobites. An abundant fauna from the upper Wenlock has yielded an association of Warbugella with Calymene species and Proetus (Proetus).


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