Trilobites and stratigraphy of the Middle Ordovician Killeröd Formation, Scania, Sweden

Abstract: The Killeröd Formation ("Bronnii beds or Coscinorrhinus limestone") is a thin, but distinctive formation in the Middle Ordovician, upper Uhakuan Stage, of southeastern Scania, the southernmost province of Sweden. It is about 70 cm thick and consists of alternating grey microcrystalline limestone and blue-grey shaly mudstone. The Killeröd Fm is richly fossiliferous and has yielded a fairly extensive fauna that mainly consists of trilobites, but also includes brachiopods, conodonts and ostracodes. The trilobite fauna is dominated by trinucleid trilobites. These include Botrioides bronnii (Boeck, 1838), B. efflorescens (Hadding, 1913) and B. impostor Owen, 1987. Other trilobites are Arthrorhachis sp., Bronteopsis holtedahli Skjeseth, 1955, Lonchodomas rostratus (Sars, 1835), Nileus platys Schrank, 1972, Platycalymene dilatata (Tullberg, 1882), platycalymene? sp., Pseudomegalaspis patagiata (Törnquist, 1884), Remopleurides sp., and Telephina aff. granulata (Angelin, 1854). The trilobite fauna of the Killeröd Formation bears a close resemblance to those found in the lower Andersö Shale in Jämtland, central Sweden, and the upper Elnes Formation in the Oslo Region of Norway. It is conc1uded that the trilobite fauna of the Killeröd Formation is indicative of the Hustedograptus teretiusculus Zone. This is in accordance with the conodontbased correlations provided by Bergström (1973).