Body size trends and recovery amongst bivalves following the end-Triassic mass extinction

Abstract

This is a repository copy of Body size trends and recovery amongst bivalves following the end-Triassic mass extinction.

Bivalve body-size distribution through the Late Triassic mass extinction event

“…Our results agree with previous studies that have suggested that final recovery in the United Kingdom is reached in the late Hettangian (e.g., Barras and Twitchett 2007; Mander et al 2008; Pugh et al 2014; Atkinson and Wignall 2019, 2020; Atkinson et al 2019). Although not sampled in this study, previous analyses have also demonstrated that the sizes of benthic marine invertebrates continued to increase into the early Sinemurian (e.g., Barras and Twitchett 2007).…”

“…Ammonites that survived the LTE expanded their body size by more than 10% toward the top of the Hettangian (Dommergues et al 2002). Studies at community level from sites within the United Kingdom confirm a progressive accumulation of larger bivalve taxa through the Blue Lias Formation (Mander et al 2008), and recent studies (Atkinson and Wignall 2019, 2020) confirm our observations, demonstrating that body-size increase is driven mainly by newly originated clades.…”

“…The patterns of body-size changes recorded in this study resemble those recorded in studies of other extinction events (Payne 2005; Morten and Twitchett 2009; He et al 2010; Rego et al 2012; Martinez-Diaz et al 2016; Sigurdsen and Hammer 2016; Rita et al 2019; Piazza et al 2019; Foster et al 2020) and add new insights to previous studies of the LTE. For instance, Mander et al (2008), Atkinson and Wignall (2019, 2020), Atkinson et al (2019), and Wignall and Atkinson (2020) reported changes in species composition between the Westbury Formation and Cotham Member (Lilstock Formation) and recorded an apparent reduction of body size of new arrivals and surviving taxa during the early recovery interval (i.e., the Langport Member). This study confirms the same changes during the extinction interval, although the changes in body size are complex.…”

“…The temporary reduction in the body size of surviving species in the immediate aftermath of an extinction event was termed the “Lilliput Effect” by Urbanek (1993), and although there are several potential reasons why such a phenomenon could be recorded in the fossil record (Twitchett 2007; Harries and Knorr 2009), in most cases, the smallest sizes are associated with peak temperatures and global warming, and so likely reflect responses to environmental change. During the recovery from mass extinction events, the sizes of surviving taxa and newly originating taxa increase as environmental conditions ameliorate (Payne 2005; Barras and Twitchett 2007; Novack-Gottshall 2008; Metcalfe et al 2011; He et al 2016; Sigurdsen and Hammer 2016; Brom et al 2018; Atkinson et al 2019; Atkinson and Wignall 2020; Foster et al 2020).…”

“…Secondary environmental effects resulting from global warming have also been inferred, including ocean acidification (Crne et al 2011), widespread anoxia (Jaraula et al 2013; He et al 2020), and rapid sea-level change (Hallam and Wignall 1999). Evidence of body-size changes has been recorded in a variety of taxa at different spatial and temporal scales during the LTE (Dommergues et al 2002; Barras and Twitchett 2007; Atkinson et al 2019; Atkinson and Wignall 2020), but no studies have examined how the ecological collapse associated with the LTE modified the BSD of marine organisms at local and regional scales.…”