Permian–TriassicOsteichthyes (bony fishes): diversity dynamics and body size evolution

Abstract

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, 'palaeopterygians', 'subholosteans') and a second one during the Middle Triassic ('subholosteans', neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle-Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.

Microvertebrates from the classic Rhaetian bone beds of Manor Farm Quarry, near Aust (Bristol, UK)

“…Extinctions occurred at different points through the Late Triassic, including during the end-Triassic mass extinction itself, and there were major extinctions and turnovers among sharks (Cappetta, 1987;Friedman and Sallan, 2012) and marine reptiles (Thorne et al, 2011). Bony fishes, on the other hand, were apparently little affected by the end-Triassic event, with all families crossing the boundary into the Jurassic (Friedman and Sallan, 2012;Romano et al, 2014). On land, dinosaurs were rising in importance, and the precursors of many modern tetrapod groups had emerged in the Late Triassic, among them the first lissamphibians (frogs and salamanders), turtles, lepidosaurs (basal sphenodontians), crocodylomorphs, and mammals (Sues and Fraser, 2010;Benton et al, 2014).…”

The oldest record of gnathostome fossils from Greece: Chondrichthyes from the Lopingian of Hydra Island

“…The new chondrichthyan material from the Wuchiapingian (Early Lopingian) of Hydra Island represents the oldest gnathostome remains of Greece, and adds a new occurrence to the relatively poor late Permian fish fossil record (Koot, 2013;Romano et al, 2016). Coeval occurrences from the western Paleotethys are mainly known from Western and Central Europe (Koot, 2013).…”

“…Despite the catastrophic impact of this mass extinction event for most groups (e.g., Benton and Twitchett, 2003), many osteichthyan clades as well as euselachians were less severely affected (Friedman and Sallan, 2012;Koot, 2013;Romano et al, 2016). Recent works have improved our understanding of the Permian chondrichthyan fossil record (Ginter et al, 2010;Hampe et al, 2013;Hodnett et al, 2013;Ivanov et al, 2013;Koot, 2013;Koot et al, 2013;Chahud and Petri, 2014;Ivanov and Lebedev, 2014;Ivanov et al, 2015), but the latter remains sporadic and less well known in comparison to that of the Triassic (Hampe et al, 2013;Koot, 2013;Koot et al, 2013 and references therein).…”

Little Evidence for Enhanced Phenotypic Evolution in Early Teleosts Relative to Their 'Living Fossil' Sister Group

“…This perspective became enshrined in mid-20th century treatments of actinopterygian evolution, which recognized an early-mid Mesozoic phase dominated by holosteans sensu lato and a later interval, extending to the modern day, dominated by teleosts (4,20,21). Contemporary paleontological accounts echo the classic interpretation of modest teleost origins (22)(23)(24), despite a systematic framework that substantially revises the classifications upon which older scenarios were based (22)(23)(24)(25). Identification of explosive lineage diversification in nested teleost subclades like otophysans and percomorphs, rather than across the group as a whole, provides some circumstantial neontological support for this narrative (26).…”

“…In contrast to quantified taxonomic patterns (20,23,24,27), phenotypic evolution in early neopterygians has only been discussed in qualitative terms. The implicit paleontological model of morphological conservatism among early teleosts contrasts with the observation that clades aligned with the teleost stem lineage include some of the most divergent early neopterygians in terms of both size and shape ( Fig.…”