Karadockie aparaty szczekowe wieloszczetow z polnocnej Estonii i regionu Petersburga

An abundant, diverse and well-preserved fauna of jaw-bearing polychaetes (Annelida, Polychaeta, Eunicida) was recovered from the late Viruan (Caradoc) of eight borehole sections in North Estonia and the St. Petersburg region. Altogether 46 species are encountered. Two new genera, Incisipnon with type species I. incisus (Kielan-Jaworowska, 1966) and Estonioprion with type species E. maennili sp. n., and five new species (Incisiprion edentulus, Polychaetura kielanae, Ramphoprion bialatus, Ramphoprion peterburgensis, Estonioprion maennili) are introduced. In addition 17 new species are described under open nomenclature. The taxonomy is based on jaw apparatuses, fused or reconstructed ones. Many species found in Estonia have been previously described from the erratic boulders of Poland. The studied polychaete fauna was confined to the North Estonian Confacies, a shallow-water carbonate shelf, which constituted favourable habitats for Ordovician polychaete worms. The stratigraphical ranges of many prevalent polychaete species exceed the interval studied. However, a few species seem to be restricted to particular horizons and may be useful for stratigraphy. Polychaete assemblages of certain time intervals, characterized by very steady species composition and relative frequencies of different taxa, were spatially widespread within the North Estonian Confacies. Based on the changes in the assemblages, some stratigraphical levels, like the boundary beds of the Idavere and Jõhvi stages, can be traced within the study area. The jawed polychaete faunas of Baltica and Laurentia probably had several species in common during the Caradoc.Z osadów późnego wiruanu (karadok) z ośmiu wierceń na obszarze półocnej Estonii i z regionu Petersburga wydobyto liczne dobrze zachowane aparaty szczękowe wieloszczetów z rodziny Eunicidae. Ogółem oznaczono 46 gatunków wieloszczetów. Wyróżniono dwa nowe rodzaje: Incisiprion, z gatunkiem typowym I. incisus (Kielan-Jaworowska, 1966) i Estonioprion, z gatunkiem typowym E. maennili sp. n. Opisano tez pięć nowych gatunków: Incisiprion edentulus, Polychaetura kielanae, Ramphoprion bialatus, Ramphoprion peterburgensis i Estonioprion maennili. Ponadto w nomenklaturze otwartej opisano 17 nowych gatunków. Systematykę oparto na aparatach złożonych z kilku szczęk, lub zrekonstruowanych na podstawie izolowanych szczęk. Liczne gatunki znalezione w Estonii były poprzednio opisane z ordowickich głazów narzutowych Polski. Badana fauna wieloszczetów występuje w Estonii na obszarze wapiennego szelfu, na którym w ordowiku panowaly korzystne warunki dla rozwoju tej grupy. Zasięgi stratygraficzne wielu badanych gatunków przekraczają interwał, z którego pochodzi badana fauna. Jednakże niektóre gatunki wydają się być ograniczone do określonych poziomów i mogą być użyteczne dla stratygrafii. Na podstawie zmian w zespołach wieloszczetów w poszczególnych poziomach karadoku, w pracy tej wyróżniono pewne poziomy stratygraficzne oparte na wieloszczetach, jak, np. warstwy przejściowe między piętrami Idavere i Jõhvi. Wiele gatunków wieloszczetów w karadoku było zapewne wspólnych dla regionu Bałtyckiego i Kanady

Ordovician polychaeturid polychaetes: Taxonomy, distribution and palaeoecology

The fossil polychaete family Polychaeturidae is considered as monogeneric and comprises four species of the genus Pteropelta. Pteropelta, originally established on isolated scolecodonts (the carriers), is revised and the apparatus−based Polychaetura is shown to be a junior synonym of Pteropelta. In addition to Pteropelta gladiata and Pteropelta kielanae, Pteropelta hubertisp. nov., and Pteropelta sp. A are herein described from the Upper Ordovician of Estonia and Sweden. Polychaeturids include some of the most common and characteristic scolecodont−bearing polychaetes in the Ordovician of Baltoscandia. They first appeared in the early Darriwilian (Mid Ordovician), flourished in the Late Ordovician and disappeared in the early Silurian. The distribution patterns of individual polychaeturid species infer regional biostratigraphical potential. Polychaeturids were geographically widespread during the Ordovician and have been recorded from at least three palaeocontinents

Darriwilian (Middle Ordovician) conodont biostratigraphy in NW Estonia

Darriwilian conodonts have been studied in numerous sections of Baltoscandia, but few data are available from the classical outcrop area in northern Estonia. In this paper we report the succession of Darriwilian conodonts and chitinozoans from the bed-by-bed sampled Uuga and Osmussaar cliffs, NW Estonia. Standard Baltoscandian conodont and chitinozoan zones and subzones were identified from the topmost Volkhov to Uhaku regional stages. The global Dapingian–Darriwilian boundary coincides with the Volkhov–Kunda boundary in NW Estonia. The Kunda Stage is represented by its middle or upper part only, and the Aseri Stage is probably missing in both sections studied. The lowermost part of the Lasnamägi Stage with the conodont Yangtzeplacognathus foliaceus is also very condensed. The rest of the Lasnamägi and Uhaku stages, corresponding to the main part of the Pygodus serra conodont Zone, is well represented and can be correlated across Estonia and Sweden. Subtle regional variations in this interval indicate very uniform depositional conditions over wide areas of the Baltoscandian palaeobasin. Our results suggest that the Y. foliaceus Subzone in Estonia needs further assessment. Stratigraphically well-constrained Y. protoramosus appears to be more common than previously thought, and is thus a valuable regional subzonal index. The integrated conodont and chitinozoan scale provides more than 20 biostratigraphically important levels for local and regional correlations, probably approaching temporal resolution in the order of 0.1 Ma for the late Darriwilian

Acritarchs from the Ordovician-Silurian boundary beds of the Valga-10 drill core, southern Estonia (Baltica) and their stratigraphical and palaeobiogeographical implications

Fourteen samples of the Valga-10 drill core, south Estonia, from the lower Jelgava Formation (middle Pirgu Regional Stage, Upper Katian) to the lowermost Ohne Formation (lowermost Juuru Regional Stage, Lower Rhuddanian) were investigated for acritarchs. The section is biostratigraphically and chemostratigraphically well constrained; it comprises the rugata, taugourdeaui and scabra chitinozoan zones, the ordovicicus and giradeauensis conodont zones and the Hirnantian Isotopic Carbon Excursion (HICE). The good preservation allowed the identification of three prasinophyte phycomata and 52 acritarch species including the four new species Evittia porkuniensis, Helosphaeridium tongiorgii, Nexosarium leherissei and ?Veryhachium bulliferum. One new combination is proposed: Poikilofusa obliquipunctata (Uutela & Tynni 1991) comb. nov. Comparison with contemporaneaous palynofloras shows that eastern Laurentia and Baltica share a high number of species during the latest Katian-Hirnantian. Some of these species show a potential for future improvement of biostratigraphical correlation between the uppermost Katian-Hirnantian strata of low to mid-latitude carbonate platforms in eastern Laurentia and Baltica. Conversely, significant taxonomic differences exist between the assemblage studied and typical Gondwanan palynofloras. These results suggest that the Laurentian/Baltic and Gonwanan phytoplanktonic palaeoprovinces existed during latest Ordovician times. Published data reveal similar distribution pattern for chitinozoans and graptolites during the Hirnantian. A bathymetric ridge rise associated with the opening of the Rheic Ocean, coupled with the Hirnantian glacially-driven sea-level fall might have prevented water mass exchange and mixing/migration of phytoplankton between Gondwana and Laurentia/Baltica, thus being at the origin of the observed acritarch bioprovincialism. Additionally, distribution and diversity patterns of acritarchs are compared to those of other microfossils in the Valga-10 section. Near the base of the Hirnantian (Porkuni Regional Stage), benthic organisms (ostracods and scolecodonts) and phytoplankton (acritarchs) show increasing diversity with appearances of new taxa and new morphologies. Planktonic (chitinozoans) and nektonic (conodonts) organisms show a different pattern, with a decline in diversity during the earliest Hirnantian and a marked increase in the later part of the stage. Two alternative hyptotheses are proposed to explain these differences in diversification patterns: (1) the development of a shallower, proximal environment in the locality studied during the Hirnantian glaciation may have been more favourable to the diversification of benthonic organisms; (2) the planktonic and nektonic organisms suffered the effects of glaciation more than benthonic ones

Cryptospore assemblages from Upper Ordovician (Katian-Hirnantian) strata of Anticosti Island, Quebec, Canada, and Estonia: Palaeophytogeographic and palaeoclimatic implications

Rich palynological assemblages have been recovered from deposits of Hirnantian age in Anticosti Island (Quebec, Canada), and in borehole Valga-10 in southern Estonia. The assemblages are well preserved, and include acritarchs, chitinozoans. and cryptospores. The age of the deposits is well constrained by means of palynomorphs (acritarchs and chitinozoans) as well as sequence stratigraphic and chemostratigraphic correlations. Cryptospore assemblages from the two localities are similar and are also broadly comparable to the few known coeval assemblages described elsewhere. They include 11 genera and 20 species, and testify to the presence of an extended and diverse flora during Hirnantian times in Laurentia and, for the first time, also in Baltica. The present findings contribute to an improved knowledge of origin and early development of vegetative cover. The recovery of diverse and abundant cryptospores in Himantian deposits may be related to increased input of land-derived sediment during the global sea-level fall linked to the Late Ordovician glaciation, but it also demonstrates that the early land plants may have tolerated a wide range of climatic conditions. (C) 2011 Elsevier B.V. All rights reserved

Ordovician polychaeturid polychaetes: Taxonomy, distribution and palaeoecology

The fossil polyclinic family Polychaeturidae is considered as monogeneric and comprises four species of the genus Pteropelta. Pteropelta, originally established on isolated scolecodonts (the carriers), is revised and the apparatus-based Polychaetura is shown to be a junior synonym of Pteropelta. In addition to Pteropelta gladiata and Pteropelta kielanae. Pteropelta huberti sp. nov., and Pteropelta sp. A are herein described from the Upper Ordovician of Estonia and Sweden. Polychaeturids include some of the most common and characteristic scolecodont-bearing polychaetes in the Ordovician of Baltoscandia. They first appeared in the early Darriwilian (Mid Ordovician), flourished in the Late Ordovician and disappeared in the early Silurian. The distribution patterns of individual polychaeturid species infer regional biostratigraphical potential. Polychaeturids were geographically widespread during the Ordovician and have been recorded from at least three palaeocontinents