Stratigraphic ranking of selected invertebrate fossils: A quantitative approach at different temporal and geographic scales

Abstract

Fossil groups are used for biochronological dating of rocks for decades. This manuscript presents a quantitative approach to appraise and compare the quality of selected taxa as biostratigraphic markers. Based on species occurrence of ammonites, bivalves, and planktic and benthic foraminifers we evaluate the potential of these to rank them quantitatively. The spatiotemporal analyses of occurrence data (species duration, geographic range) were integrated in results of the Unitary Association method, which measures superpositional contradictions in addition to the generation of a number of UAs. The results indicate that Jurassic ammonites have the lowest species duration, and that the majority of species is confined to a single UA-zone. Additionally, ammonites have the lowest numbers of contradicted bio-events. However, planktic foraminifers are more valuable at least in the Cenozoic as they have a high geographic reproducibility and diversity, and higher ISP values. The bivalves and benthic foraminifers both show longer average species durations and more superpositional contradictions per species. Therefore, their biostratigraphic potential is more limited at an interregional scale. The shorter species durations of ammonites and planktic foraminifers in the studied sections can be attributed to their higher extinction rates. As an advantage to simple spatio-temporal analyses, the UA-method can accurately assess the stratigraphic potential of a given taxonomic group. The results obtained herein indicate that the life-habit has direct impact on the species duration and thus, the stratigraphic potential of the fossil groups. Based on the results achieved from this study, an index for ranking fossil groups (Index of Stratigraphic Potential 'ISP') is introduced.

Cyclic nature of the biotic attributes of macroinvertebrate communities in the Cenomanian–Turonian strata of Sinai: water depth-driven biological responses

“…As the plot is straight to the right in all of the studied section (Fig. 5d), the data are interpreted to be sufficient for quantitative analyses and thus, adding new samples will have no or very little effect on the result (i.e., robust results; Abdelhady et al 2018Abdelhady et al , 2019b.…”

“…The biostratigraphic analysis was carried out using the unitary association (UA) method, which can provide improved biochronological results (Pálfy et al 2003;Pálfy 2007;Galster et al 2010;Monnet et al 2011;Guex et al 2015;Klein and Korn 2016), even for benthic taxa (e.g., Abdelhady and Fürsich 2015b;Abdelhady et al, 2019b). The occurrence data of the macrofossils in the measured sections were compiled into a presence/absence matrix, with the samples in rows and taxa in columns (Appendix S1) and analysed using PAST (Hammer et al 2001).…”

“…the occurrence of UAs in geographically distant sections), which enables correlations to be determined among the different sections. Where UAs have no geographic reproducibility and so the correlation is not possible, they should be grouped to enable correlation among different sections (for a summary, see Abdelhady et al 2018Abdelhady et al , 2019bFig. 5c).…”