K/T Impact Remains in an Ammonite from the Uppermost Maastrichtian of Bidart Section (French Basque Country)

Ammonites on the Brink of Extinction: Diversity, Abundance, and Ecology of the Order Ammonoidea at the Cretaceous/Paleogene (K/Pg) Boundary

“…Using a statistical method employing 50 % confidence intervals, Marshall and Ward (1996) argued that at least two of these species persisted to the boundary. Indeed, in both areas, recent, intense collecting has yielded additional specimens in the uppermost Maastrichtian, consistent with the previously noted statistical predictions (Rocchia et al 2002;Olivero 2012;Tobin et al 2012).…”

“…The top 1.5 m in the combined sections at Zumaya, Hendaye, and Bidart contain approximately 40 specimens representing ten species, although only one of these specimens is present in the highest 10-15 cm of the section (Ward 527 19 Ammonites on the Brink of Extinction: Diversity, Abundance … and Kennedy 1993). In addition, Rocchia et al (2002) reported the occurrence of a poorly preserved specimen from 5 cm below the boundary clay at Bidart, which contains Ni-rich spinel crystals and an anomalously high concentration of iridium. Marshall and Ward (1996) also used statistical methods (confidence intervals) to examine the ranges of ammonite species in the top 1.5 m of the composite section in the Bay of Biscay to determine the likelihood that the actual ranges extended above the observed ranges.…”

“…In the Bay of Biscay, ten species are present in the top 1.5 m of the section, and one species is present in the top 10-15 cm of the section (Ward and Kennedy 1993). Rocchia et al (2002) also noted the occurrence of a poorly preserved specimen filled with iridium debris at 5 cm below the boundary clay. Based on the temporal interpretation of the alternation of limestone and marl beds in this area, the two highest specimens were buried at less than 500-800 years prior to the boundary (Rocchia et al 2002).…”

“…Rocchia et al (2002) also noted the occurrence of a poorly preserved specimen filled with iridium debris at 5 cm below the boundary clay. Based on the temporal interpretation of the alternation of limestone and marl beds in this area, the two highest specimens were buried at less than 500-800 years prior to the boundary (Rocchia et al 2002). Near Maastricht, in the Netherlands and northeast Belgium, 19 species are present near or at the K/Pg boundary in the upper part of the Nekum Member and overlying Meerssen Member.…”

“…This region of southwestern France and northeastern Spain encompasses many K/Pg sections that are apparently continuous and complete (Wiedmann 1987(Wiedmann , 1988aKennedy 1993;Ward and Kennedy 1993;Ten Kate and Sprenger 1993;Rocchia et al 2002). The strata consist of massive marls with rare turbidites deposited in an outer-shelf setting with water depths of 100-500 m (Mathey 1982;Schulte et al 2010).…”