Lower Ordovician conodonts from Köpings klint, central Öland, and the feeding apparatuses of Oistodus lanceolatus Pander and Acodus deltatus Lindström
Abstract: Köpings klint is located on Öland, SE Sweden and expose a sequence of Lower Ordovician rocks from the boundary between the Tremadoc and the Arenig. The strata are correlated with the Paltodus deltifer, the Paroistodus proteus and the Oepikodus evae conodont Zones. The sediment was mostly deposited in a shallow, subtidal marine environment, but the Oepikodus evae Zone is correlated with a major transgression. The species Oepikodus evae can be used as a facies indicator, suggesting outer shelf and generally deeper water environments than the subtidal zone, which is more normal for the platform deposits in the Lower Ordovician of Öland. Provincialism of conodonts, where two major faunal regions dominate, are known from the early Ordovician. The two major faunal regions are the North Atlantic faunal region and the Midcontinental faunal region. The conodonts from Köpings klint belong to the North Atlantic faunal region with few exceptions, as for example the taxon Tropodus sp. The feeding apparatuses of the species Acodus deltatus and Oistodus lanceolatus are here described as hyalion apparatuses. A hyalion apparatus consists of a pair of M-elements, a transition series of S-elements and two pairs of P-elements. The elements are placed in a symmetrical pattern, with the symmetrical Sa-element in a mirror plane in the centre.
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