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| the diversification of living large-bodied (> 2 m) marine predatory fishes such as tunas and mackerels (Scombridae) in Brownstein, Alencar, Kindsvater, Thacker, Wainwright, Near et Harrington, 2026. |
Abstract
The assembly of modern ocean ecosystems was fundamentally affected by the Cretaceous–Palaeogene (K-Pg) mass extinction. Among the casualties of this event were many extinct clades of large pelagic predatory fishes. The extinction of these lineages is thought to have created ecological opportunity that spurred the diversification of living large-bodied (> 2 m) marine predatory fishes such as tunas and mackerels (Scombridae). However, it remains unclear whether a large, endothermic body plan evolved in tunas and mackerels directly after the K-Pg boundary or in a stepwise manner throughout the Cenozoic. Here, we demonstrate that Scombridae, which includes half of living endothermic ray-finned fish species, evolved endothermy and large body sizes long after the initial radiation of the clade at the K-Pg boundary. Our time-calibrated phylogeny also reveals that the origins of endothermy, large body size and increased longevity in true tunas are staggered over evolutionary time. These findings indicate that the evolution of large endothermic scombrids was not triggered by the K-Pg extinction and substantiate the protracted development of the endothermic predatory body plans of tunas and relatives over more than 50 million years of evolutionary history.
Keywords: Scombridae, tunas, phylogenomics, K-Pg mass extinction, endothermy
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| Origin of large body sizes in Scombridae. The phylogeny is coloured according to the ancestral state reconstruction for log-transformed standard length. Warmer colours indicate body sizes approaching 4 m. Body size increases over 2 m are denoted by Roman numerals. The innermost dashed circle indicates the K-Pg boundary. Illustrations of scombrids are by Julie Johnson (lifesciencestudios.com). |
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| Tempo of trait shifts in Scombridae. Inferred histories of significant trait optima shifts across Scombridae plotted on the time-calibrated phylogeny of this clade. Shifts inferred with over 30% posterior probability are included. The full bayou outputs are in the electronic supplementary material associated with this article. Illustrations of scombrids are by Julie Johnson (lifesciencestudios.com). |
Chase D. Brownstein; Laura R. V. Alencar; Holly K. Kindsvater; Christine E. Thacker; Dylan K. Wainwright; Thomas J. Near and Richard C. Harrington. 2026. The prolonged Reemergence of Megapredatory Pelagic Fishes. Proc Biol Sci. 293 (2074): 20261257. DOI: doi.org/10.1098/rspb.2026.1257 [08 Jul 2026]
