Results 11 to 20 of about 169 (141)
A new chitinozoan species from the Middle Ordovician of Estonia [PDF]
Estonian Journal of Earth Sciences, 2012 A new species Baltochitina delicata is formally defined. This rare species has been identified in the Aseri Regional Stage (Darriwilian) in North Estonian sections. The genus Baltochitina was known so far only by a single species B. nolvaki, which occurs
Jaak Nõlvak
doaj +2 more sources
Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs [PDF]
Proceedings of the Royal Society B: Biological Sciences, 2019 Joseph Bernardo +2 more
exaly +2 more sources
Early and early Middle Ordovician chitinozoans from the Baldone drill core, central Latvia [PDF]
Estonian Journal of Earth Sciences, 2022 Early and early Middle Ordovician chitinozoans are relatively poorly known in Baltoscandia, thus the understanding of the early diversification of the group, as well as its biostratigraphic utility, is limited. In this paper, we document the distribution
Jaak Nõlvak, Yan Liang, Olle Hints
doaj +1 more source
Boundary between the Porkuni and Juuru regional stages in the Neitla section, Estonia [PDF]
Estonian Journal of Earth Sciences, 2023 Conodonts and chitinozoans were studied from the Neitla section, which exposes the boundary between the Porkuni and Juuru regional stages. This level, although not proved biostratigraphically, has been traditionally considered to correspond to the ...
Peep Männik, Jaak Nõlvak
doaj +1 more source
The detailed Middle to early Late Ordovician faunal succession and δ13Ccarbon chemistry of the Kårehamn drill core, offshore eastern Öland, Sweden: implications for stratigraphy and correlation [PDF]
Estonian Journal of Earth Sciences, 2023 The Middle to lower Upper Ordovician stratigraphy of the KÃ¥rehamn core, drilled ca 7 km offshore to the east of the KÃ¥rehamn village, northeastern Ãland, is presented. The investigated core is one of four drill cores obtained during the preparation of
Svend Stouge +4 more
doaj +1 more source
Latest Ordovician age of the Spinachitina fragilis Chitinozoan Biozone in Baltoscandia [PDF]
Estonian Journal of Earth Sciences, 2023 The global Spinachitina fragilis Chitinozoan Biozone has been considered the lowermost Silurian zone in most publications. S. fragilis was first described from the Ohesaare drill core, Estonia, and utilised as a Baltic regional zonal taxon together with ...
Jaak Nõlvak, Yan Liang, Olle Hints
doaj +1 more source
The role of clay minerals in the preservation of Precambrian organic‐walled microfossils
Geobiology, Volume 21, Issue 6, Page 708-724, November 2023., 2023 Abstract Precambrian organic‐walled microfossils (OWMs) are primarily preserved in mudstones and shales that are low in total organic carbon (TOC). Recent work suggests that high TOC may hinder OWM preservation, perhaps because it interferes with chemical interactions involving certain clay minerals that inhibit the decay of microorganisms.
C. R. Woltz +3 more
wiley +1 more source
Paleoceanography and Paleoclimatology, Volume 38, Issue 2, February 2023., 2023 Abstract New δ34Spy (pyrite) and δ34SCAS (carbonate‐associated sulfate) across the Llandovery‐Wenlock boundary (∼432 Ma) provide evidence for the expansion of reduced marine environments during the Ireviken Biogeochemical Event. This event consists of a major positive carbon isotope excursion, increased biotic turnover, and other major perturbations ...
Brittany M. Stolfus +7 more
wiley +1 more source
AGU Advances, Volume 3, Issue 1, February 2022., 2022 Abstract The Ordovician (Hirnantian; 445 Ma) hosts the second most severe mass extinction in Earth history, coinciding with Gondwanan glaciation and increased geochemical evidence for marine anoxia. It remains unclear whether cooling, expanded oxygen deficiency, or a combination drove the Late Ordovician Mass Extinction (LOME).
Nevin P. Kozik +4 more
wiley +1 more source
Lethaia, Volume 54, Issue 5, Page 610-630, December 2021., 2021 The Mora 001 and Solberga 1 drill cores provide the best available overview on the early Silurian (Llandovery, Rhuddanian to Telychian) graptolite succession available for the Siljan Ring impact structure of central Sweden. The Solberga 1 succession includes a nearly complete graptolite succession from the Pernerograptus revolutus Biozone (late ...
Jörg Maletz
wiley +1 more source