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On the biostratigraphical significance of the Ordovician acritarch genus Liliosphaeridium on Oeland, Sweden
No full textThe 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 establishe
The Ordovician acritarch genus Pachysphaeridium Burmann 1970: new, revised & reassigned species
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Paleontological evidence for Late Cambrian in the Arburese area, SW Sardinia
No full textNew palynological investigations allowed a better definition of the age of terrigenous deposits of the Monte Fonnesu tectonic Unit, exposed in the Arburese area (SW Sardinia). The section investigated consists of a coarsening upwards positive sequence, up to 10 m thick, that is made up of quartz-arenitic sandstones and light gray quartzite beds (0.5 m thick), interbedded with thin beds of black shale. In the lower part of the section, two quartzitic levels are rich in lingulid (brachiopods) shell fragments. This is the first report of macrofossils from the Monte Fonnesu Unit. Samples collected for palynological analyses in the black shale at the base and at the top of the lowest quartzitic level yielded a Late Cambrian acritarch microflora that can be correlated with the Peltura trilobite Superzone. The Late Cambrian age assigned to the lower part of the sequence allows us to define more precisely the age of Mt. Fonnesu sandstone, which in consequence is bracketed between the Late Cambrian and the Early Ordovician
Ordovician acritarch genera Peteinosphaeridium, Liliosphaeridium, and Cycloposphaeridium: morphology, taxonomy, biostratigraphy, and palaeogeographic significance
No full textLate Cambrian acritarch Lusatia: Taxonomy, palaeogeography, and biostratigraphic implications.
No full textIntraspecific variability of the herein emended diacrodian acritarch Lusatia dendroidea is described based on late Cambrian (Furongian) well preserved material from Spain, the High Arctic of Russia, and the East-European Platform. L. dendroidea, displays bipolar asymnietric morphology and, as originally defined, consists of three long major processes originating from the "corners" of its vesicle. Specimens with one, two and four major processes are considered to represent morphological variations of the most common three process form. Based on its narrow stratigraphic range, wide-spread palaeogeographic distribution, and distinctive morphology, L. dendroidea is an excellent guide fossil for the Furongian
Early Jurassic age for youngest Beacon Supergroup strata base on polynomorphs fron Section Peak, Northern Victoria Land, Antarctica
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