The stratigraphic distribution of the Ordovician genus Liliosphaeridium Uutela and Tynni 1991 emend. Playford et al. 1995 has been examined in five sections on the northern part of the island of Öland, Sweden. The investigated interval spans the Volldaov - Kunda boundary. The genus has been re-examined taxonomically and four new species have been established: L. brevicalix, L. pocillum, L. tintinnabulum, and L. trinatum. In these new species, a trend involving progressive reduction of the vesicle wall ornamentation and increase in the height of the calyx of the processes can be observed. L. tintinnabulum n. sp. is a significant species for biostratigraphical correlations, being present in a short interval in different palaeogeographical areas such as Baltic regions, South China, and North Africa. On Öland, the stratigraphical range of the genus Liliosphaeridium is confined to the glauconitic limestones of the informal formations A and B in an interval comprised between the lower part of the Baltoniodus norrlandicus and the Yangtzeplacognathus crassus conodont Zones. The first occurrence on Öland of representatives of the genus Liliosphaeridium could correspond to the base of Darriwilian Stage, as recently established
On the biostratigraphical significance of the Ordovician acritarch genus Liliosphaeridium on Oeland, Sweden
BAGNOLI, GABRIELLA;
2001-01-01
Abstract
The stratigraphic distribution of the Ordovician genus Liliosphaeridium Uutela and Tynni 1991 emend. Playford et al. 1995 has been examined in five sections on the northern part of the island of Öland, Sweden. The investigated interval spans the Volldaov - Kunda boundary. The genus has been re-examined taxonomically and four new species have been established: L. brevicalix, L. pocillum, L. tintinnabulum, and L. trinatum. In these new species, a trend involving progressive reduction of the vesicle wall ornamentation and increase in the height of the calyx of the processes can be observed. L. tintinnabulum n. sp. is a significant species for biostratigraphical correlations, being present in a short interval in different palaeogeographical areas such as Baltic regions, South China, and North Africa. On Öland, the stratigraphical range of the genus Liliosphaeridium is confined to the glauconitic limestones of the informal formations A and B in an interval comprised between the lower part of the Baltoniodus norrlandicus and the Yangtzeplacognathus crassus conodont Zones. The first occurrence on Öland of representatives of the genus Liliosphaeridium could correspond to the base of Darriwilian Stage, as recently establishedI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
