An extraordinary discovery from the depths of geological time has unveiled the earliest known example of a fish possessing an intricate dental adaptation— a ‘tongue bite’ mechanism—dated to over 310 million years ago. This fossilized ray-finned fish, Platysomus parvulus, represents an unprecedented insight into the evolution of complex feeding strategies long before previously recognized. Using cutting-edge high-resolution computed tomography (CT) scanning, researchers have reconstructed the internal anatomy of this ancient creature, revealing a remarkable oral arrangement unlike any other from its era. This finding dramatically pushes back the timeline for sophisticated biting adaptations among early vertebrates.
The fossilized specimen of Platysomus parvulus emerges from Carboniferous strata in Staffordshire, United Kingdom, and is exquisitely preserved in three dimensions. This exceptional preservation has allowed the scientific team to digitally examine the fish’s oral cavity in extraordinary detail, uncovering a unique dental morphology. Unlike most contemporary fish that primarily employ their jaws for biting and processing food, this species utilized a specialized apparatus comprising tooth plates located on both the roof of the mouth and the gill arches—structures historically not associated with feeding. These plates formed a complementary biting surface, functioning akin to a secondary jaw, facilitating the crushing of hard prey items such as shells and tough exoskeletons.
The phenomenon known as a ‘tongue bite’ involves a complex interaction between opposite sets of teeth, where the floor of the mouth works in tandem with the upper oral surface to exert crushing force from within the buccal cavity. Modern fish families such as trout and bonefish exhibit analogous systems, employing similar secondary biting mechanisms to expand their dietary range. However, until now, the oldest known occurrences of such adaptations were documented in species dating roughly 150 million years after Platysomus parvulus. This discovery thus redefines our understanding of early vertebrate oral functional diversity and underscores an early evolutionary experimentation with novel predation methods.
The detailed CT scans revealed a multi-layered lower tooth plate accompanied by a narrow upper plate, each bearing a single row of pointed teeth optimized for gripping and pulverizing prey. This arrangement suggests an evolutionary intermediate form, bridging the gap between simple jaw-biting fishes and the highly specialized tongue biters of later geological periods, such as those belonging to the genus Bobasatrania. The latter, noted for their even more advanced and jaw-independent feeding strategies, rely exclusively on the tongue bite apparatus to manipulate and crush hard food, indicating a progressive refinement of this unique mechanism across evolutionary time.
This discovery carries profound implications for the post-End-Devonian Mass Extinction narrative. Following this catastrophic global event approximately 360 million years ago, which resulted in the decimation of numerous marine species, ray-finned fishes underwent an evolutionary radiation that fostered novel morphologies and ecological niches. The finding that such a complex dental adaptation appeared so early during this diversification underscores the rapid functional innovations that characterized this pivotal interval in vertebrate evolution and the dynamic experimental landscape of feeding apparatus evolution.
The discovery was enabled by advanced imaging technologies that allow paleontologists to non-destructively visualize fossil internal structures in three dimensions with unparalleled precision. This non-invasive digital dissection revealed the arrangement of tooth plates embedded in the gill skeleton—an anatomical feature traditionally regarded as primarily supportive rather than actively involved in feeding mechanics. Such rearrangements demonstrate an extraordinary evolutionary plasticity of cranial and oral structures, wherein existing anatomical parts assumed new roles facilitating survival advantages amidst ecological upheavals.
Lead author Professor Sam Giles from the University of Birmingham highlights the evolutionary importance of this finding, stating that the emergence of tongue bite systems in different fish lineages exemplifies convergent evolution, where analogous functional solutions arise independently in diverse groups. This capacity for multifunctional dental systems equipped fish to exploit a wider array of food sources, contributing to their ecological success in varied habitats. The presence of this mechanism in such an ancient species challenges established paradigms regarding the pace and complexity of vertebrate feeding evolution.
Co-author Dr. Matthew Kolmann from the University of Louisville emphasizes the transitional nature of Platysomus parvulus. Unlike later fishes with fully developed tongue bites that rendered jaw function obsolete, this species demonstrates an intermediate anatomical and functional condition. Such evolutionary intermediates are crucial for reconstructing the stepwise enhancements that culminated in specialized feeding strategies, shedding light on the modular evolution of vertebrate oral systems and adaptive radiations following mass extinctions.
Professor Matt Friedman of the University of Michigan adds context to the broader ecological significance of these findings. Feeding innovations such as the tongue bite are part of a suite of morphological and behavioral adaptations that restructured ancient aquatic ecosystems, dictated predator-prey dynamics, and paved the way for modern fish lineages. These complex adaptations indicate that even early in their diversification, ray-finned fishes exhibited a remarkable developmental plasticity and ecological versatility that contributed to their prolonged evolutionary success.
The research, published in Biology Letters, was supported through collaborative efforts involving paleontologists and evolutionary biologists across several institutions, including the University of Birmingham, Natural History Museum London, University of Louisville, and University of Michigan. It underscores the power of integrating paleontological data with state-of-the-art imaging to revise fundamental biological narratives and reinterpret long-standing assumptions about vertebrate evolutionary history.
This unprecedented glimpse into the ancient evolutionary experimentation documented by Platysomus parvulus opens new avenues for understanding the development of complex functional structures in vertebrates. It emphasizes an evolutionary landscape rich in innovation well before the Jurassic period and highlights the strategic importance of oral diversification in vertebrate survival and ecological adaptation.
In sum, the discovery of the 310-million-year-old tongue bite apparatus in Platysomus parvulus not only enriches the fossil record of early ray-finned fishes but also challenges long-held perceptions regarding the tempo and mode of feeding adaptations. It signals a remarkable evolutionary experimentation phase during the early Carboniferous, paving the way for the biodiversity and complexity witnessed in modern aquatic ecosystems.
Subject of Research: Not applicable
Article Title: Tongue bite apparatus highlights functional innovation in a 310-million-year-old ray-finned fish
News Publication Date: 3-Sep-2025
Image Credits: Joschua Knüppe
Keywords: Paleontology, Animal fossils, Vertebrates, Fossil records
