The Belemnella stratigraphy of the Campanian– Maastrichtian boundary; a new methodological and taxonomic approach

Abstract

Remin, Z. 2012. The Belemnella stratigraphy of the Campanian-Maastrichtian boundary; a new methodological and taxonomic approach. Acta Geologica Polonica, 62 (4), 495-533. Warszawa. The taxonomy and stratigraphy of the Upper Campanian and Lower Maastrichtian belemnites from the Vistula (central Poland) and Kronsmoor (northern Germany) sections are revised on the basis of new collections from the Vistula section as well as a reinvestigation of the classic collection of Schulz from the Kronsmoor section. For the taxonomic description a new biometric procedure is proposed, which can be applied to both the genera Belemnella and Belemnitella. For the species-level taxa recognition the Artificial Neural Networks method, the self-organizing Kohonen algorithm, was implemented. This new taxonomic and methodological approach enabled the recognition of nine species of the genus Belemnella. Five of them can be assigned to the existing species B. lanceolata, B. longissima , B. inflata, B. obtusa and B. vistulensis. However, the species concept differs from that applied by Schulz (1979). As a consequence, the stratigraphic ranges of these species are modified. Four species are left in open nomenclature and represent possibly new species. Future studies may reveal that they might be assigned to East European forms from Ukraine or Russia. The species of Belemnella recognized are placed into the stratigraphic framework based on the standard ammonite and inoceramid bivalve zonations, especially those recognized in the Vistula section. The newly proposed belemnite zonation for the Vistula and Kronsmoor sections is correlated via inoceramids with the standard GSSP at Tercis, France, in order to identify the base of the Maastrichtian Stage. The Campanian-Maastrichtian boundary as defined in Tercis is placed here at the base of the newly defined B. obtusa and B. vistulensis Zones [“obtusa/vistulensis”] - thus it is markedly higher than the traditional boundary based on the FAD of representatives of the genus Belemnella . This new boundary coincides well with a distinct turnover of belemnite guard morphology and represents one of the most important points in the early evolutionary history of Belemnella. Three belemnite zones defined by their lower boundaries are recognized in the Campanian-Maastrichtian interval, in addition to three subzones recognized within the B. obtusa Superzone. The B. lanceolata and B. inflata zones as understood here are referred to the Upper Campanian [Tercis definition]. The B. obtusa Zone is subdivided into three subzones, viz.: Belemenlla vistulensis, Belemnella sp. G and Belemnella sp. F, which are referred to the Lower Maastrichtian [Tercis definition]. The fast evolving species of Belemnella enable the proposal of a biostratigraphic scheme with a resolution that is higher than those based on inoceramid bivalves and ammonites - the longevity of a belemnite zone could be as low as 200Ky.

The Belemnitella stratigraphy of the Upper Campanian – basal Maastrichtian of the Middle Vistula section, central Poland

“…Con se quently, the belem nite strati graphic sub di vi sion of the Lower Maastrichtian is based pri mar ily on Belemnella (see dis cus sion in Remin, 2012).…”

“…The terms and measure ments used for bel em nites de scrip tion fol low Christensen (1995) and Remin (2008Remin ( , 2012 and are sum ma rized in Figure The ma te rial stud ied was sub di vided into three strati graphic sam ples, each con sist ing of a suf fi cient num ber of guards: (1) Sadkowice Szko³a-Sadkowice N; (2) Raj and (3) Raj N-Dziurków (Raj N, Podole, K³udzie, Przedmieoecia and Dziurków). Bel em nites from each strati graphic sam ple were analysed in de pend ently us ing a two-lay ered Kohonen neu ral network with 29 in puts (29 char ac ters of the guard; Fig.…”

“…I -Mid dle Vistula sec tion (cen tral Po land) -this ar ti cle; Ia -Belemnella zones of the Mid dle Vistula sec tion (Remin, 2012); II -NW Eu rope, Belemnella zones af ter Schulz (1979), Belemnitella zones (af ter e.g., Christensen, 1995Christensen, , 1999Christensen, , 2000b; III -Rus sian Plat form (e.g., Naidin, 1975Naidin, , 1979; IV -con ven tional bel em nite zones (Jeletzky, 1951a(Jeletzky, , b, 1958Birkelund, 1957); base of the Maastrichtian ac cord ing to (1) the stratotype in Tercis, France; (2) the con ven tional sub di vi sion for the Bo real Realm, based on bel em nites…”

“…The study has been car ried out ac cord ing to Remin's (2012) meth od ol ogy, based on ar ti fi cial neu ral net works (ANN) (Fausett, 1994;Haykin, 1994;Patterson, 1996), in par tic u lar the self-or ga niz ing Kohonen net works (Kohonen, 1982), and the inte grated bio met ric pro ce dure, in de pend ent of the ge neric mem -ber ship of the ma te rial. The pow er ful al go rithm used by Kohonen net works is com monly used to solve dif fer ent kinds of clas si fi ca tion prob lems and was successfuly ap plied to species-level tax o nomic rec og ni tion in bel em nites (Remin, 2007(Remin, , 2008(Remin, , 2012Remin in Niebuhr at al., 2011), and e.g., to Pa leozoic cor als (Wrzo³ek and Remin, 2008).…”

“…The pow er ful al go rithm used by Kohonen net works is com monly used to solve dif fer ent kinds of clas si fi ca tion prob lems and was successfuly ap plied to species-level tax o nomic rec og ni tion in bel em nites (Remin, 2007(Remin, , 2008(Remin, , 2012Remin in Niebuhr at al., 2011), and e.g., to Pa leozoic cor als (Wrzo³ek and Remin, 2008). The study is the first attempt at cor re lat ing Eu ro pean Belemnitella pop u la tions from dif fer ent re gions, us ing the new meth od olog i cal ap proach and the new in te grated bio met ric pro ce dure.…”