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标题：Early representatives of the belemnite genus Belemnella (Cephalopoda) from the uppermost Campanian–Lower Maastrichtian of the Middle Vistula River section, central Poland
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作者：Norbert Keutgen ; Zbigniew Remin ; Ireneusz Walaszczyk 等
期刊名称：Acta geologica Polonica
印刷版ISSN：0001-5709
出版年度：2012
卷号：62
期号：4
页码：535-559
语种：English
出版社：Institute of Geology, University of Warsaw
摘要：Representatives of the belemnite genus Belemnella from the uppermost Campanian and lowermost Maastrichtian of the Middle Vistula River Valley section (central Poland) have been studied, using the species concept proposed by Schulz in 1979. Results have been compared to a recently proposed new interpretation of the genus Belemnella based on artificial neural networks, as put forward by Remin in 2007 and 2012. In the interval studied, four taxa have been recognised: Bln. longissima, Bln. inflata, Bln. obtusa and Bln. vistulensis, the last-named being a senior synonym of Bln. pseudobtusa. Three additional forms have been left in open nomenclature: Bln. cf. lanceolata, Bln. ex gr. lanceolata/inflata and Belemnella sp. Based on their documented vertical ranges, three Belemnella standard zones, as originally distinguished in the Kronsmoor section by Schulz (1979), northern Germany, have been defined, in ascending order: the Bln. lanceolata, Bln. vistulensis and Bln. obtusa zones. The bases of the lanceolata and obtusa zones in the Middle Vistula River Valley section can be directly correlated with the same zones at Kronsmoor, and appear to be isochronous within limits of stratigraphic resolution. The base of the vistulensis Zone (Bln. vistulensis according to the species concept of Schulz in 1979), however, is probably diachronous, being older in the Middle Vistula section. Although Schulz’s and Remin’s species concepts differ quite considerably, they do result in similar stratigraphic subdivisions of the Kronsmoor and Middle Vistula River sections.
关键词：Belemnella;Biostratigraphy;Species concepts;Middle Vistula River section;Campanian–Maastrichtian boundary.