Middle Aptian biostratigraphy and ammonoids of the Northern Caucasus and Transcaspia

The Early Aptian (Cretaceous) stratigraphy of Mount Pagasarri (N Spain): Oceanic anoxic event‐1a

“…Moreover, the Kilian Group (Reboulet et al, 2014) (Casey, 1961). Dufrenoyia and Cheloniceras associated with Epicheloniceras, Colombiceras, and ancyloceratids, such as Tropaeum, which span the latest Early Aptian and earliest Late Aptian have been also reported in Russia (e.g., Baraboshkin, 2004;Bogdanova & Mikhailova, 2016 Epicheloniceras is clear in the Bilbao section, and the problem here is where to place the Early/Late Aptian boundary. Here, we take the last occurrence of D. dufrenoyi at about 1,600 m as the reference marker for the Early/Late Aptian boundary (Figure 7) in accordance with the Kilian Group recommendation (Reboulet et al, 2014).…”

“…The interval of co‐occurrence is followed by a marked faunal turnover with disappearance of Dufrenoyia and Cheloniceras and the general occurrence of Epicheloniceras and the first appearance of Salfeldiella guettardi marking the Epicheloniceras debile Subzone of the E. martinioides Zone (Casey, ). Dufrenoyia and C heloniceras associated with Epicheloniceras , Colombiceras , and ancyloceratids, such as Tropaeum , which span the latest Early Aptian and earliest Late Aptian have been also reported in Russia (e.g., Baraboshkin, ; Bogdanova & Mikhailova, ). In the Prebetic Domain of Spain, Moreno‐Bedmar et al () show these transitional faunas between Cheloniceras meyendorffi (d'Orbigny) and true Epicheloniceras , but here, the base of the Late Aptian, martinioides Zone is well marked by the first general occurrence of the genus Epicheloniceras .…”

“…We are satisfied that there is no miscorrelation or tectonic induced repeats in the section. Traditionally, the boundary between the two Substages has been placed at the last appearance of Dufrenoyia and the first occurrence of Epicheloniceras of the E. martinioides Zone (e.g., Bogdanova & Mikhailova, 2016;Casey, 1961;Prozorovsky, 1989;Reboulet et al, 2014;). Moreover, the Kilian Group (Reboulet et al, 2014) (Casey, 1961).…”

“…We are satisfied that there is no miscorrelation or tectonic induced repeats in the section. Traditionally, the boundary between the two Substages has been placed at the last appearance of Dufrenoyia and the first occurrence of Epicheloniceras of the E. martinioides Zone (e.g., Bogdanova & Mikhailova, ; Casey, ; Prozorovsky, ; Reboulet et al, ;). Moreover, the Kilian Group (Reboulet et al, ) places the upper limit of the furcata Zone just above the last appearance of Dufrenoyia dufrenoyi , which we record in the Bilbao Formation at a height of 1,575 m above the base of the formation (IGT‐3 ammonite station).…”

Representatives ofthe Subfamily Cheloniceratinae Spath, 1923(Ammonoidea)fromthe Aptian ofMangyshlak,Western and Southern Turkmenistan. Paper 1. General Issues. The Genus Cheloniceras Hyatt, 1900

“…Еще одной особенностью, препятствующей объединению двух подсемейств, является предполагаемый кризис в развитии и распространении представителей Cheloniceratinae в терминальной части фазы Parahoplites melchioris среднего апта (о чем свидетельствует отсутствие достоверных находок этих аммонитов в отложениях соответствующего возраста), только после которого в начале позднего апта появляются первые находки Douvilleiceratinae s. str. (род Eodouvilleiceras) [4,5].…”