Jakub Witkowski

Jakub Witkowski
University of Szczecin · Stratigraphy and Earth History

About

61
Publications
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549
Citations
Citations since 2017
27 Research Items
306 Citations
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Introduction
Working on early fossil record of siliceous phytoplankton (mostly diatoms), and variations in marine biogenic silica accumulation through the Paleogene. fossildiatoms.wordpress.com instagram.com/fossil.diatoms

Publications

Publications (61)
Presentation
The Paleogene period (~66 to ~23 Ma) was characterized by an initial extreme warmth, followed by a gradual cooling of the climate. Many mechanisms have been proposed to explain it, including feedbacks involving enhanced silicate weathering and high rates of marine primary production. One challenge for paleoproductivity reconstructions in the early...
Book
The Blake Nose area (western North Atlantic) represents the longest currently available single-locality record of diatom evolution, spanning approximately 30 million years of the early Cenozoic Era. This study provides a detailed taxonomic account of the diatom assemblages found in the lower Paleocene through upper Eocene deep-sea sediments recover...
Article
Cenozoic silicoflagellate evolution led to ten known genera derived from two groups classified together in Corbisema that may have survived the end-Cretaceous extinction. These underwent rapid diversification and gave rise to at least five genera before the end of the Paleocene, including Dictyocha and Naviculopsis. Important silicoflagellate evolu...
Article
Based on scanning electron and light microscope examination of Triceratium radiatum Brightwell, Entogoniopsis gleseri Sims, Witkowski, Strelnikova & Williams, and Entogoniopsis sp. 1 of Witkowski et al. (2015), we propose a new genus of fossil diatoms, Crawfordia. It is characterised by multipolar, pseudocellate valves with trifolia and prominent i...
Article
This short paper is comprised of four notes on, or related to, the genus Stictodiscus Greville (1861a: 39) based, for the most part, on specimens in BM (Natural History Museum, London) and a correction to the type designation of Aulacodiscus madagascarensis Tempère noted in a previous publication (Williams 2021: 158)
Preprint
Full-text available
The Paleogene history of biogenic opal accumulation in the North Atlantic provides insight into both the evolution of deep-water circulation in the Atlantic basin, and weathering responses to major climate shifts. However, existing records are compromised by low temporal resolution and/or stratigraphic discontinuities. In order to address this prob...
Article
Full-text available
The Paleogene history of biogenic opal accumulation in the North Atlantic provides insight into both the evolution of deepwater circulation in the Atlantic basin and weathering responses to major climate shifts. However, existing records are compromised by low temporal resolution and/or stratigraphic discontinuities. In order to address this proble...
Article
Full-text available
Diatomites are prolific hydrocarbon source rocks in many basins worldwide. In the broader Carpathians, diagenetically altered diatomites are called menilites, and menilitic shale successions are regarded as the most prolific hydrocarbon source rocks in the region. The abandoned Sibiciu de Sus quarry, located in the Eastern Carpathian Bend Zone of R...
Article
The composition and distribution of deep-sea sediments is the result of a multitude of climatic, biotic and oceanic conditions relating to biogeochemical cycles and environmental change. Here we utilize the extensive sediment archives of the International Ocean Discovery Program (IODP) and its predecessors to construct maps of deep-sea sediment typ...
Article
The widespread occurrence of lower Eocene chert and porcellanite has been viewed as a major paleoceanographic issue since the advent of ocean drilling, and both biotic and abiotic forcings have been proposed to explain it. We present a reconstruction of indurated siliceous sediment (ISS) and preserved biosiliceous sediment (PBS) occurrences in the...
Article
Full-text available
Diatomaceous sediments are often prolific hydrocarbon source rocks. In the Paratethys area, diatomaceous rocks are widespread in the Oligo-Miocene strata. Diatomites from three locations, Szurdokpüspöki (Hungary) and Limberg and Parisdorf (Austria), were selected for this study, together with core materials from rocks underlying diatomites in the L...
Article
Full-text available
Ocean Drilling Program (ODP) Site 1051 (Blake Nose, western North Atlantic) is of crucial importance for reconstructing diatom evolution and biosiliceous sedi- mentation patterns through the early Cenozoic period of extreme greenhouse warmth followed by the progressive global cooling. The magnetostratigraphy in Hole 1051A, however, has been subject...
Article
Full-text available
Although previous phylogenetic analyses suggested that the araphid diatom family Plagiogrammaceae is monophyletic, there is still not a clear understanding of relationships among the genera, and the taxonomy of several genera --Dimeregramma and Plagiogramma--remains questionable in light of paraphyly for both genera using molecular and morphologica...
Article
Full-text available
The Oligocene Ruslar Formation, an equivalent of the Maykop Suite, is a potential hydrocarbon source rock in the western Black Sea Basin. In contrast to the offshore areas, the depositional environment and hydrocarbon source rock potential of onshore Bulgaria sediments are largely unknown. Hence, a 14-m-thick section of the Ruslar Formation, expos...
Article
The naviculopsid morphology, which consists of an arch across the minor axis of a basal ring with two corners and sides, is the simplest of the Cenozoic silicoflagellate skeletal designs that include an apical structure. This skeletal design is most often associated with the genus Naviculopsis (geologic range: middle Paleocene to early Miocene), bu...
Data
Fence diagram showing nannofossil- and silicoflagellate-based correlation of Holes 208, 752A, 1121B and 700B. Stratigraphic columns are arranged according to increasing palaeolatitude.
Data
Comparison of the Palaeocene–Eocene silicoflagellate biostratigraphic zonation proposed in McCartney et al. 2018 to previous southern subtropical to subpolar zonal schemes.
Article
Full-text available
Early Palaeocene through early Eocene silicoflagellate assemblages were examined from five southern subtropical through subpolar deep-sea sites: DSDP Holes 208 and 524, and ODP Holes 700B, 752A, and 1121B. For each site, the taxonomic composition of the silicoflagellate assemblage is documented in detail; Pseudonaviculopsis gen. nov., Dictyocha cas...
Data
Morphometry plot for Fenneria brachiata (Brightwell) J. Witkowski, including data from onshore and deep-sea sites. Color-coding represents the synonyms reported from the respective sites in the published records.
Data
Comparison of the timing of diatom datums between Sites 338, 1051 and 1260. Based on published records referenced in Witkowski et al. (2018).
Article
Full-text available
Triceratium barbadense Greville, 1861a, T. brachiatum Brightwell, 1856, T. inconspicuum Greville, 1861b and T. kanayae Fenner, 1984a, are among the most common diatoms reported worldwide from lower to middle Eocene biosiliceous sediments. Due to complicated nomenclatural histories, however, they are often confused. A morpho- metric analysis perform...
Article
The so-called Oamaru Diatomite dates from approximately the Eocene–Oligocene Transition (∼34 million years ago), which is widely regarded as one of the most important climatic events of the entire Cenozoic era due to global cooling and the onset of continental-scale Antarctic glaciations. It also represents one of the richest fossil diatom deposits...
Article
Catalogue of diatom names resurrected: diatombase will be the new authority resource for diatom names and more.
Article
Silicoflagellate skeletons are made up of siliceous components that interconnect through triple-junctions to form a basket-shaped design made of basal and apical structures. The skeletal framework has a domal shape that can be paired with another to form a double skeleton. For Cenozoic skeletal morphologies, the basal structure consists of a ring o...
Chapter
Full-text available
Marine microfossils are produced by a variety of microorganisms that may be auto- or heterotrophic or planktic or benthic. Although most marine microfossils are body fossils of single-celled organisms (protists), some are small-sized elements of macrobiota, e.g., conodont elements or sponge spicules. The vast majority of marine microfossils possess...
Article
Full-text available
In this paper presented are the results of light and electron microscopic studies on a marine dia-tom species Biddulphia seychellensis. The species turned out to be abundant in some samples from the west coast of South Africa and from the western Indian Ocean coral reefs of Scattered Islands (Eparses). Unlike most representatives of the genus, B. s...
Article
We present the results of an extensive light-(LM) and scanning electron microscope (SEM) study of internally costate pseudocellate multipolar diatoms previously placed within Biddulphia, Entogonia, Sheshukovia and Triceratium. For the first time, we critically examine the poorly known genus Sheshukovia. We find that the separation of Sheshukovia fr...
Article
Modern silicoflagellates are known to produce double skeletons, which are considered as pre-division stages; members of modern doublets are aligned at basal corners, using either pikes or organic material between the abbasal surfaces of the basal rings to hold together. In contrast, fossil doublets from the Cretaceous and Paleogene often have the c...
Article
Two of the oldest known silicoflagellate-bearing sediments, lower Albian at Ocean Drilling Program Site 693 in the Weddell Sea of Antarctica and Santonian in the Devon Island sequence of the Canadian Archipelago, are re-examined with a focus on silicoflagellate genera Variramus, Cornua, and Gleserocha that lack basal rings, a feature appearing duri...
Article
Les plus anciens silicoflagellés provenant des sédiments de l’Albien inférieur du Site 693 de l’Ocean Drilling Program (ODP) dans la mer de Weddell en Antarctique et des sédiments du Santonien des îles Devon de l’archipel arctique canadien sont revus, afin de mieux comprendre les genres Variramus, Cornua et Gleserocha qui ne possèdent pas d’anneau...
Article
The Middle Eocene Climatic Optimum (MECO; ~ 40 million years ago [Ma]) is one of the most prominent transient global warming events in the Paleogene. Although the event is well documented in geochemical and isotopic proxy records at many locations, the marine biotic response to the MECO remains poorly constrained. We present new high-resolution, qu...
Article
Full-text available
Two, rare double skeletons of Corbisema silicoflagellates have been observed from Early and Middle Eocene sediments. Both specimens are in the Star-of-David configuration, with the basal corners of each skeleton aligned with the middle of sibling basal sides. These specimens are of a species that has an elongate basal ring, which shows that skeleto...
Article
Valve structure of the Cretaceous diatom Hemiaulus giganteus Souse ex Strelnikova is documented using light- and scanning electron microscopy. A lectotype for H. giganteus is established based on the presumed type material of Souse from Bolschoi Aktai River basin, Sverdlovsk District, Russia. We compare the morphology of H. giganteus to the generit...
Data
The Middle Eocene Climatic Optimum (MECO; ~ 40 million years ago [Ma]) is one of the most prominent transient global warming events in the Paleogene. Although the event is well documented in geochemical and isotopic proxy records at many locations, the marine biotic response to the MECO remains poorly constrained. We present new high-resolution, qu...
Article
Nine samples of broad Late Cretaceous age, previously studied by the respected Russian diatomistA.P. Jousé, were reexamined in order to document the taxonomic composition of silicoflagellates at several localities within the Ural Federal District of Russia. New observations are provided on the range of morphological variability in several important...
Article
Full-text available
Scanning electron and light microscope observations are presented of Biddulphia brittoniana Kain & Schultze, B. heteroceros Grunow and B. multicornis Grunow. All these species possess unusual modes of chain formation, including entangling spines and clasping of the external tubes of the rimoportulae. The three species are transferred to Cerataulus...
Article
The Middle Eocene Climatic Optimum (MECO) is a major transient warming event that occurred at ~ 40 Ma and reversed a long-term cooling trend through the early and middle Eocene. We report the results of a high-resolution, quantitative study of siliceous microfossils at Ocean Drilling Program Sites 748 and 749 (Southern Kerguelen Plateau, Southern O...
Article
Full-text available
This study documents two new species of the genus Pseudoaulacodiscus, P polyakovae and P simsiae, from Eurasian and North American Upper Cretaceous marine sediments. Based on new data, the generic description of Pseudoaulacodiscus is emended. Previously unknown morphological features that reaffirm the opinion that Pseudoaulacodiscus comprises hemia...
Data
The Middle Eocene Climatic Optimum (MECO) is a major transient warming event that occurred at ~ 40 Ma and reversed a long-term cooling trend through the early and middle Eocene. We report the results of a high-resolution, quantitative study of siliceous microfossils at Ocean Drilling Program Sites 748 and 749 (Southern Kerguelen Plateau, Southern O...
Article
We present four genera of bipolar centric diatoms with linking structures located on the valve face: Rutilaria (including two new species from the Cretaceous), Spinivinculum, Pseudorutilaria and Kisseleviella, which are commonly classified in the family Rutilariaceae. Functional comparison of their linking structures and modes of chain formation sh...
Article
Upper Cretaceous sediments of the Kanguk Formation exposed in Eidsbotn and Viks Fiord grabens on Devon Island, Nunavut, Canadian High Arctic, yielded 91 fossil marine diatom species and varieties (including indeterminate taxa), representing 41 genera. Excellent preservation of the assemblages was aided by shallow burial, protection in downfaulted l...
Article
Diverse and well-preserved assemblages of early to late Campanian silicoflagellates from the Smoking Hills andMason River formations exposed in the District ofMackenzie, Northwest Territories, Canada include twenty-one known species and five new species in six genera. These include a rare occurrence ofCornua trifurcata and unusual skeletalmorpholog...
Article
Full-text available
Three varieties of the silicoflagellate Lyramula simplex based on distinct morphological expressions are documented herein from the Campanian Smoking Hills and Mason River Formations of the Mackenzie District in the Northwest Territories, Canadian Arctic. The presence of two new morphological structures broaden the species concept for this taxon to...
Article
Full-text available
Recent studies of Santonian and Campanian sediments from several sites in northern Canada identified two new silicoflagellate genera, many new and unusual species, a Santonian assemblage of Variramus and abundant specimens of the poorly known genus Cornua. This allowed a reassessment of Variramus with information from three new species, and transfe...
Article
Two new genera of fossil diatoms, Blochia gen. nov. and Nikolaevia gen. nov., are proposed from Kanguk Formation (Upper Cretaceous) outcrops on Devon Island, Canadian Arctic margin. Both genera display morphological features suggesting a relationship with Stellarima Hasle & Sims. Nikolaevia is unusual in having an external opening of the rimoportul...
Article
A recently discovered deposit of Late Cretaceous diatoms on Devon Island contains exceptionally well-preserved siliceous microfossils. Two diatom taxa from this deposit, previously identified as belonging to the genera Actinodictyon and Lepidodiscus, were examined with light and scanning electron microscopy. The present study revealed that these tw...
Article
Full-text available
As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada,...

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