The Rise of Jaw Protrusion in Spiny-Rayed Fishes Closes the Gap on Elusive Prey

Abstract

Jaw protrusion is one of the most important innovations in vertebrate feeding over the last 400 million years [1, 2]. Protrusion enables a fish to rapidly decrease the distance between itself and its prey [2, 3]. We assessed the evolution and functional implications of jaw protrusion in teleost fish assemblages from shallow coastal seas since the Cretaceous. By examining extant teleost fishes, we identified a robust morphological predictor of jaw protrusion that enabled us to predict the extent of jaw protrusion in fossil fishes. Our analyses revealed increases in both average and maximum jaw protrusion over the last 100 million years, with a progressive increase in the potential impact of fish predation on elusive prey. Over this period, the increase in jaw protrusion was initially driven by a taxonomic restructuring of fish assemblages, with an increase in the proportion of spiny-rayed fishes (Acanthomorpha), followed by an increase in the extent of protrusion within this clade. By increasing the ability of fishes to catch elusive prey [2, 4], jaw protrusion is likely to have fundamentally changed the nature of predator-prey interactions and may have contributed to the success of the spiny-rayed fishes, the dominant fish clade in modern oceans [5].

Feeding ecology underlies the evolution of cichlid jaw mobility

“…The strong association between diet and feeding motions that we observe in rift lake cichlids, raises the possibility that the evolution of high kinesis morphologies in spiny‐rayed fishes, whether by protrusion or hyoid depression, may have been a response to the selective demands of an increasingly predatory lifestyle (Bellwood et al. ).…”

“…), but only the presence of the trait in spiny‐rayed fishes (Acanthomorpha) appears to be associated with highly predatory activities that have increased through time (Bellwood et al. ). The strong association between diet and feeding motions that we observe in rift lake cichlids, raises the possibility that the evolution of high kinesis morphologies in spiny‐rayed fishes, whether by protrusion or hyoid depression, may have been a response to the selective demands of an increasingly predatory lifestyle (Bellwood et al.…”

The evolution of fishes and corals on reefs: form, function and interdependence

“…Phase 3, in the Late Cretaceous, encompasses the rise of the acanthomorphs, the group to which most modern reef fishes belong. It was a time of considerable morphological and molecular diversification Sallan & Friedman, 2012;Bellwood et al, 2015a). However, it is primarily in the last three phases that we see the origin of modern coral reef fishes.…”

The evolution of jaw protrusion mechanics has been tightly coupled to bentho-pelagic divergence in damselfishes (Pomacentridae)

“…Protrusile jaws have evolved multiple times among fishes (Staab et al, 2012;Wainwright et al, 2015). Two of the most successful vertebrate lineages, the Acanthomorpha (∼17,000 species) and Cypriniformes (∼3200 species), are composed of fish species that have rapidly transitioned between forms with highly protrusile upper jaws and those that exhibit little to no jaw protrusion (Hernandez and Staab, 2015;Hulsey et al, 2010;Staab et al, 2012;Wainwright et al, 2015;Bellwood et al, 2015). Both acanthomorphs and cypriniforms possess jaw arrangements that allow simple shape changes to either enhance or reduce jaw protrusion, with changes in the length of the ascending arm of the premaxilla having particular importance (Hernandez and Staab, 2015;McGee et al, 2015b;Rice et al, 2008;Staab et al, 2012).…”