Biometry and biostratigraphy of the Early Cretaceous belemnite genus Castellanibelus from the southeast of France

Abstract

Early Cretaceous deposits (Berriasian–Albian) crop out over large areas in the Vocontian Basin (VB, southeast of France). The important exposures have provided rich marine fossil faunas, including many specimens of ammonites and belemnites over the last 200 years. From the early 19th century onward, the definition of Lower Cretaceous belemnite species from the VB was essentially based on descriptive, qualitative approaches. This resulted in a variety of morphologically very closely related species, sometimes difficult to differentiate between each other. Biometric data and their statistical analysis offer a mathematical and objective framework to clearly delineate and define morphological species, especially when consecutive belemnite assemblages are continuously available from different stratigraphic levels. The present study is based on the analysis of 1762 specimens of Castellanibelus collected by ammonite zones and subzones across the entire Valanginian interval of the VB. Biometric data of this genus have been statistically analyzed and used to define four species, including one new to science: Castellanibelus orbignyanus, Castellanibelus vaubellensis, Castellanibelus suborbignyanus, and Castellanibelus toucasi sp. nov.

Keywords

• Biostratigraphy
• Belemnites
• Lower Cretaceous
• Valanginian
• Vocontian Basin
• <i>Castellanibelus</i>
• Taxonomy
• Biostratigraphy