Abstract:Foraminiferal biostratigraphy has been used extensively in the re-survey of the Chalk Group of southern England since the 1990s and a biozonation based on 21 zones and numerous subzones has been developed. The scheme is closely related to, and extensively tested against, the new lithostratigraphy for the Chalk Group based on examination of well described key chalk exposures, from significant borehole cores, many additional short sequences in chalk exposures and a large number of field samples taken throughout … Show more
“…Despite numerous micropalaeontological investigations of the Coniacian-Campanian chalks of this region by, amongst others, Earland (1939), Barr (1962) and Wilkinson (2011), none of these authors has recorded any evidence of radiolaria.…”
Radiolarians were recently discovered in the lower Eocene London Clay Formation of the London Basin from samples in a drainage borehole in the River Thames. They come from a c. 10 m thick sequence of silty shales in the lower part of the formation. The radiolarians are, in general, rather poorly preserved, with the exception of six samples that yielded moderately preserved radiolarians that allowed the identification of eighteen taxa. All radiolarians observed are of Late Cretaceous age and they are therefore reworked into the lower part of the Eocene London Clay Formation. The best preserved sample yielded an assemblage of twelve morphospecies, including Diacanthocapsa ovoidea, Theocapsomma amphora and Theocapsomma sp. aff. T. amphora sensu Popova-Goll et al. 2005, suggesting an original Santonian-Campanian age, and more likely only the Campanian. However, the stratigraphic origin of these radiolarians from the Upper Cretaceous sequence of the London Basin is uncertain.
“…Despite numerous micropalaeontological investigations of the Coniacian-Campanian chalks of this region by, amongst others, Earland (1939), Barr (1962) and Wilkinson (2011), none of these authors has recorded any evidence of radiolaria.…”
Radiolarians were recently discovered in the lower Eocene London Clay Formation of the London Basin from samples in a drainage borehole in the River Thames. They come from a c. 10 m thick sequence of silty shales in the lower part of the formation. The radiolarians are, in general, rather poorly preserved, with the exception of six samples that yielded moderately preserved radiolarians that allowed the identification of eighteen taxa. All radiolarians observed are of Late Cretaceous age and they are therefore reworked into the lower part of the Eocene London Clay Formation. The best preserved sample yielded an assemblage of twelve morphospecies, including Diacanthocapsa ovoidea, Theocapsomma amphora and Theocapsomma sp. aff. T. amphora sensu Popova-Goll et al. 2005, suggesting an original Santonian-Campanian age, and more likely only the Campanian. However, the stratigraphic origin of these radiolarians from the Upper Cretaceous sequence of the London Basin is uncertain.
“…The associated remains are referred to the classic ‘Middle Chalk Group’ of southern England (Hopson, 2005). This unit is part of the Chalk Group, specifically the White Chalk Subgroup, deposited in the northwestern part of the Anglo-Paris Basin and equivalent to the lowest part of the Lewes Nodular Chalk Formation, the New Pit Chalk Formation, and the Holywell Nodular Chalk Formation (with the exclusion of the Plenus Marls Member) in the Southern Province (Hopson, 2005; Wilkinson, 2011; Gale, 2019; Fig. 2.2).…”
Section: Geological Settingmentioning
confidence: 99%
“…2.2). The ‘Middle Chalk’ spans from the upper Cenomanian (only the Plenus Marl Member) to the middle Turonian (Wilkinson, 2011) and yielded remains of numerous fossil fish taxa, although the number of vertebrates per volume of rock is very low (Mantell, 1822; Woodward, 1902, 1903, 1907, 1908, 1909, 1911, 1912; Kriwet, 2002; Friedman et al, 2016); the ichthyofauna therein includes a large variety of bony fishes (e.g., Dixon, 1850; Woodward, 1902, 1903, 1907, 1908, 1909, 1911, 1912; Kriwet, 2002) and several cartilaginous fishes (e.g., Cretoxyrhina and Ptychodus ; Dixon, 1850; Woodward, 1902, 1903, 1907, 1908, 1909, 1911, 1912; Longbottom and Patterson, 2002). Figure.…”
The definition of the Cretaceous shark genus Cretodus Sokolov, 1965 is primarily based on isolated teeth. This genus includes five species. Among these, Cretodus houghtonorum Shimada and Everhart, 2019 is the only species based on a partially preserved skeleton. Here, the taxonomic attribution of a virtually complete skeleton of Cretodus from the Turonian of northeastern Italy is discussed, together with a few specimens from the Turonian of England. One of the latter is investigated through micropaleontological analysis to determine its stratigraphic position. The material is referred to Cretodus crassidens (Dixon, 1850), the diagnosis of which is emended herein. The dentition is tentatively reconstructed, exhibiting strong similarities with congeneric species, although it differs in having strong vertical folds on the main cusp labial face, a mesiodistally broad tooth aspect, weak and well-spaced ‘costulae’ at crown base, and a different dental formula in the number of parasymphyseal and lateral rows. Some tooth malformations are interpreted as feeding-related or senile characters. The Italian specimen suggests that Cretodus crassidens had a wide and laterally expanded mouth and head, a stout body, and attained a gigantic size. Cretodus crassidens was a moderate-speed swimming shark ecologically like the extant tiger shark Galeocerdo cuvier (Péron and Lesueur in Lesueur, 1822). The age estimate from vertebral-band counting suggests that the Italian individual was at least 23 years old and the growth model indicates a longevity of 64 years and a maximum attainable total length of 9–11 m. Cretodus crassidens occurs both in Boreal and Tethyan domains, implying a broad paleobiogeographic distribution and a preference toward offshore settings.
“…In view of the arguments provided, benthic foraminifera (mostly calcareous rotaliids) seem to have a much higher stratigraphic potential and applicablity within the entire European epicontinental Upper Cretaceous, than planktonic ones (Reuss 1860;Marsson 1878;Brotzen 1936;Marie 1941;Hiltermann 1952;Hofker 1957Hofker , 1966Vasilenko 1961;Hiltermann and Koch 1950, 1955, 1962Goel 1965;GaworBiedowa 1972GaworBiedowa , 1992Koch 1977;Bailey and Hart 1979;Edwards 1981;Akimetz et al 1978;1983;Bailey et al 1983;Peryt 1983;Hart et al 1989;King et al 1989;Schönfeld 1990;Hradecká 1996;Walaszczyk et al 2004;Hampton et al 2007;Kopaevich et al 2007;Olferiev et al 2007;Wilkinson 2011;Benyamovskiy et al 2012). …”
Section: Review Of the Biostratigraphically Critical Groups Used In Tmentioning
The biostratigraphic importance, current zonations, and potential for the recognition of the standard chronostratigraphic boundaries of five palaeontological groups (benthic foraminifers, ammonites, belemnites, inoceramid bivalves and echinoids), critical for the stratigraphy of the Santonian through Maastrichtian (Upper Cretaceous) of extra-Carpathian Poland, are presented and discussed. The summary is based on recent studies in selected sections of southern Poland (Nida Synclinorium; Puławy Trough including the Middle Vistula River composite section; and Mielnik and Kornica sections of south-eastern Mazury-Podlasie Homocline) and of western Ukraine (Dubivtsi). The new zonation based on benthic forams is presented for the entire interval studied. Zonations for ammonites, belemnites and inoceramid bivalves are compiled. All stage boundaries, as currently defined or understood, may easily be constrained or precisely located with the groups discussed: the base of the Santonian with the First Occurrence (FO) of the inoceramid Cladoceramus undulatoplicatus; the base of the Campanian with the Last Occurrence (LO) of the crinoid Marsupites testudinarius and approximated by the range of the foraminifer Stensioeina pommerana; and the base of the Maastrichtian approximated by the FO of the inoceramid bivalve Endocostea typica and the FO of the belemnite Belemnella vistulensis. The positions of substage boundaries, as currently understood, are constrained in terms of the groups discussed.
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