Trajectories of Late Permian - Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction

Abstract

The hypothesis that ocean acidification was a proximate trigger of the marine end‐Triassic mass extinction rests on the assumption that taxa that strongly invest in the secretion of calcium‐carbonate skeletons were significantly more affected by the crisis than other taxa. An argument against this hypothesis is the great extinction toll of radiolarians that has been reported from work on local sections. Radiolarians have siliceous tests and thus should be less affected by ocean acidification. We compiled taxonomically vetted occurrences of late Permian and Mesozoic radiolarians and analyzed extinction dynamics of radiolarian genera. Although extinction rates were high at the end of the Triassic, there is no evidence for a mass extinction in radiolarians but rather significantly higher background extinction in the Triassic than in the Jurassic. Although the causes for this decline in background extinction levels remain unclear, the lack of a major evolutionary response to the end‐Triassic event, gives support for the hypothesis that ocean acidification was involved in the dramatic extinctions of many calcifying taxa. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Macrofaunal Response to the End-Triassic Mass Extinction in the West-Tethyan Kossen Basin, Austria

“…The ocean acidification model predicts an increased extinction risk for taxa with an aragonite or high-Mg calcite skeletal mineralogy (Hautmann, 2004;Knoll et al, 2007;Hautmann et al, 2008a) and, thus, offers a possible explanation for the preferential extinction of reef communities, ammonoids, and aragonitic bivalves at the end of the Triassic (Hautmann et al, 2008a(Hautmann et al, , 2008b, which is in contrast to groups with such noncalcareous skeletons as radiolarians that had no significantly increased extinction risk (Kiessling and Danelian, 2011;Hönisch et al, 2012). Somewhat counterintuitively, taxa with massive or thick-shelled skeletons, including strongly ornamented forms, also appear to be at an elevated extinction risk, because decreased CaCO 3 saturation of seawater raises energy expenditure for biocalcification, which puts such taxa at a selective disadvantage (Hautmann, 2006;Knoll et al, 2007;Veron, 2008Veron, , 2011Kiessling and Simpson, 2011).…”

“…Reduced CaCO 3 saturation of seawater due to oceanic uptake of volcanogenic CO 2 and SO 2 and concomitant decrease of seawater pH (ocean acidification) is the latest extinction model for the end-Triassic marine extinction (Hautmann, 2004), which has been intensively discussed in the last years (e.g., Galli et al, 2005;Berner and Beerling, 2007;van de Schootbrugge et al, 2007;Hautmann et al, 2008a;Kiessling et al, 2008;Č rne et al, 2011;Kiessling and Danelian, 2011;. The ocean acidification model predicts an increased extinction risk for taxa with an aragonite or high-Mg calcite skeletal mineralogy (Hautmann, 2004;Knoll et al, 2007;Hautmann et al, 2008a) and, thus, offers a possible explanation for the preferential extinction of reef communities, ammonoids, and aragonitic bivalves at the end of the Triassic (Hautmann et al, 2008a(Hautmann et al, , 2008b, which is in contrast to groups with such noncalcareous skeletons as radiolarians that had no significantly increased extinction risk (Kiessling and Danelian, 2011;Hönisch et al, 2012).…”

On the accuracy of paleodiversity reconstructions: a case study in Antarctic Neogene radiolarians

“…Because of the nature of its extraordinary fossil record (very large number of individuals, relatively constant and widespread biogeographic and sedimentary regions, organisms with a wide variety of biological properties or ecological niches found together in the same samples), marine micropaleontology offers a unique resource for paleobiology (Lipps 1981;Lazarus 2011). Nonetheless, only recently have macroevolutionary studies begun to exploit this potential by using large, global data sets (Rabosky and Sorhannus 2009;Kaminski et al 2010;Liow et al 2010;Kiessling and Danelian 2011;Lloyd et al 2011;Ezard et al 2011), thanks to the creation and the use of fossil occurrence databases such as the Paleobiology Database (Alroy et al 2001), mostly for Mesozoic microfossil data, and the Neptune database Spencer-Cervato 1999), the latter containing much of the (largely Cenozoic) microfossil occurrence data published in the context of the DSDP/ ODP drilling campaigns.…”

Radiolarian biodiversity dynamics through the Triassic and Jurassic: implications for proximate causes of the end-Triassic mass extinction

“…On the other hand, the much-studied early Toarcian Oceanic Anoxic Event (Jenkyns 2010) and the related second-order extinction is said to be manifested in elevated radiolarian turnover. Hori (1997) described a Toarcian radiolarian event from bedded cherts of Japan, but this has not been confirmed from elsewhere, and a distinct extinction peak is not evident at the stage level (Kiessling and Danelian 2011).…”

“…However, the radiolarian range data of Sepkoski (2002) are rather outdated and some radiolarian workers maintain that the group was seriously hit by the end-Triassic event (Carter and Hori 2005). A recent sampling-standardized analysis of the radiolarian fossil record from the Late Permian to Late Jurassic concluded that although Rhaetian extinction rates were higher than in Sepkoski's compendium, there is no evidence for an end-Triassic mass extinction (Kiessling and Danelian 2011). Instead, the end-Triassic extinctions fall within the background of generally elevated Triassic extinction rates.…”