Generic turnovers of Carnian/Norian conodonts: Climatic control or competition?

The calcareous nannofossil <i>Prinsiosphaera</i> achieved rock-forming abundances in the latest Triassic of western Tethys: consequences for the <i>δ</i><sup>13</sup>C of bulk carbonate

“…For this study, we focused on the late Norian, Rhaetian and early Jurassic portions of the succession (Fig. 2), which are well constrained by conodont biostratigraphy (Mazza et al, 2010(Mazza et al, , 2012, calcareous nannofossils and radiolarians (Preto et al, 2012). In this interval, the succession is comprised of chertpoor, cream to whitish nodular limestones, passing upward to whitish porous plane-bedded limestones (chalks).…”

“…Stable isotope records of Triassic successions based on bulk carbonate, as given by, to name a few, Payne et al (2004), Horacek et al (2007), Muttoni et al (2004) and Mazza et al (2010), and, in part, Korte et al (2005), should thus be interpreted with extreme caution in the absence of an adequate discussion of diagenetic processes. Once the precipitation of carbonate in the pelagic realm becomes firmly established, deep-water lime mudstones may instead be mostly made of calcareous plankton, and should retain the seawater δ 13 C more easily.…”

The Carnian/Norian boundary succession at Berlin-Ichthyosaur State Park (Upper Triassic, central Nevada, USA)

“…However, the section is of great 1464 interest for its abundant conodont faunas, which are pres-1465 ently under study by MJO, and its well-preserved ammo-1466 noid faunas of the Kerri and Dawsoni zones. In this respect, 1467 Juvavites cove provides the best record of the Kerri zone in 1468 the Williston Lake area, and it is not coincidental that 1469 Tozer (1994) (Orchard et al 2001;1588Orchard 2007, and in particular the parvus 1589 zone, with that of the Tethys (Mazza et al 2010(Mazza et al , 2011(Mazza et al , 1590(Mazza et al 2012 (Fig. 14), the second GSSP candidate section for the 1656 base of the Norian, must be examined and it is useful to 1657 emphasize some problems whose solutions are necessary in 1658 order to define the calibration of the North American and 1659 Tethyan chronostratigraphic scales.…”

“…Literature regarding a possible algal blooming 1323 influence on fossil cephalopods is also quite meager, con-1324 sisting only of a report of mass mortality of Jurassic 1325 coleoidea (Wilby et al 2004). Muttoni et al 2001Muttoni et al , 2004Mazza et al 2010Mazza et al , 2011Mazza et al , 20121350Muttoni et al 2014 (2010), but this sampling is considered adequate 1370 to at least place the position of the C/N boundary within the 1371 52-m thick still unsampled interval between samples BIS17 Available ammonoid data are shown in Fig. 13 …”

“…1663 Although the succession is very rich in conodonts (Mazza 1664(Mazza et al 2010(Mazza , 2011(Mazza , 2012 and Halobia (Levera 2012), as 1665 well as radiolarian faunas at certain levels (Nicora et al 1666(Nicora et al 2007Balini et al 2010a, b), its ammonoid record is not 1667 particularly abundant . Figure 14 pro-1668 vides a summary of ammonoid and Halobia distribution as 1669 well as an updated chronostratigraphic subdivision of the 1670 section based on ammonoid occurrences (Balini et al 1671, which directly tie the succession to Tethyan 1672 ammonoid chronozones and Halobia species (Levera 1673, whose ranges are now rather well calibrated with the 1674 ammonoid chronostratigraphy.…”