The placoderms in question lived around 385 million years ago during the Devonian Period, often called the Age of Fishes, in the rich marine ecosystems of the famous Gogo Formation in Western Australia. This world-renowned fossil site has been the focus of decades of research, including long-running collaborations with the local Gooniyandi and Gogo community, and has yielded some of the most exquisitely preserved three-dimensional fish fossils ever discovered. It was here that these armoured predators hunted other armoured creatures on an exotic ancient reef, and it is here that the fossil evidence for their feeding strategies has been locked away in stone, waiting for modern technology to unlock it.

Dr Alice Clement, an ARC Future Fellow at the Flinders Palaeontology Lab and a co-author of the study, explains that placoderms present an extraordinary natural experiment in the early evolution of biting. Placoderms experimented with an extraordinary range of jaw shapes and biting parts during the early evolution of vertebrates, she notes, providing a rare opportunity to understand how some of the first jaws became specialised for different diets. Unlike most animals alive today, including humans, placoderms did not possess a single lower jaw bone. Instead, their jaws were built from paired bony plates supported by cartilage, with biting surfaces that ranged from broad, flat crushing plates to sharp slicing edges armed with tooth-like structures. This anatomical diversity makes them ideal subjects for investigating how jaws first became adapted to different kinds of food.

To probe that diversity, the research team employed a technique borrowed from engineering known as finite element analysis. First author Dr Rex Mitchell, of the College of Science and Engineering at Flinders University, together with colleagues, created digital three-dimensional models of the fossil jaw bones and then performed computer-based bite simulations on them. These simulations measure how well each jaw structure could withstand and support the forces generated during biting, effectively stress-testing extinct animals in silico. The team then compared the mechanical performance of each jaw with the anatomical complexity of its biting surface, looking for patterns that might connect jaw shape to diet and feeding behaviour across the eight species they examined.

Conventional wisdom in biomechanics holds that animals feeding on hard foods, such as shells and bone, generally evolve stronger jaws with broader, flatter crushing surfaces, much like the nutcracker jaws of modern hyenas or the durophagous dentitions of many rays and wrasses. That is not exactly what the analysis revealed. Rather than finding a simple, predictable relationship between jaw strength and surface shape, the researchers discovered something unexpected: both the largest and the smallest placoderms in the study possessed the strongest jaws for handling hard bites, despite using completely different biting tools. The smallest species had broad, almost featureless crushing plates, while the largest species carried highly complex, elevated dental surfaces that bore little resemblance to their diminutive relatives.

It was an interesting surprise, says PhD student and co-author Austin Fitzpatrick. Both the smallest and largest animals had evolved strong jaws, he explains, but they had solved the problem of processing harder foods in completely different ways. The key to this paradox, the researchers suggest, lies in the relationship between predator and prey body size when the prey in question is wrapped in tough exterior armour. A small placoderm confronting a small armoured prey item did not need to break it apart at all. The prey could simply be engulfed whole and then pulverised between broad, flat biting plates, much as some modern fish swallow and crush small shelled invertebrates. Strength was essential, but anatomical complexity was not.

Larger prey presented an entirely different challenge. An armoured animal too big to fit inside a predator’s mouth first had to be broken into manageable pieces before it could be eaten. That requirement demanded more elaborate dental architecture, capable of first piercing through shell or armour before crushing the remains. The largest species in the study possessed teeth arranged along a raised bony crest, forming a structure that the researchers describe as strikingly similar to the heads of medieval armour-piercing weapons such as war hammers and poleaxes. This fearsome configuration suggests the fish used its jaws to puncture the protective coverings of its prey before breaking them apart, functioning less like a nutcracker and more like a can opener followed by a hammer.

The broader significance of the finding is that hard-object feeding among Earth’s earliest jawed vertebrates was not achieved through a single evolutionary solution. Evolution, in other words, produced a diversity of jaw designs that allowed different placoderm species to exploit different prey within the same ancient reef ecosystem, a pattern ecologists call niche separation. Two species could both be powerful biters specialised for hard-shelled food, yet occupy genuinely different ecological roles depending on what they could fit in their mouths and how they had to dismantle it. This paints a picture of the Devonian reef as a complex, ecologically structured environment in which early vertebrates were already carving out specialised feeding niches hundreds of millions of years before the first tetrapods crawled onto land.

The study also reinforces the central place of placoderms in the story of human evolution. Flinders Emeritus Professor John Long, a co-author who has worked at the Western Australian fossil site for 40 years and found some of the specimens used in this study, emphasises that since 2013 placoderms have been directly linked to our own lineage as the starting point of the line leading from fishes to humans. Understanding placoderms, he argues, is now vital to revealing the origins of the human body plan. Their jaws, in particular, represent the evolutionary foundation upon which all later vertebrate mouths, from shark snouts to human faces, were ultimately built, making every new insight into how these structures functioned a contribution to a deeply personal chapter of natural history.

Technically, the study demonstrates the growing power of combining finite element analysis with comparative three-dimensional morphology to answer ecological questions that fossils alone cannot resolve. By measuring jaw strength numerically and then mapping it against surface complexity, the team could infer not only what these extinct fish ate but also how large their prey must have been relative to their own bodies, turning bite mechanics into a proxy for ancient food webs. The work, supported by the Australian Research Council through Discovery Projects funding, contributes to a growing picture of niche separation and ecological specialisation in the ancient Devonian reef. It shows that within a few tens of millions of years of jaws first appearing, vertebrates had already diversified into an impressive array of feeding specialists, from whole-swallowing crushers to armour-piercing giants, foreshadowing the extraordinary ecological breadth of jawed vertebrates that continues to this day.

Subject of Research: Feeding mechanics and jaw evolution in Devonian placoderms from the Gogo Formation, Western Australia

Article Title: Jaws tell tales: How ancient armoured fish munched prey whole

Article References: Jaws tell tales: How ancient armoured fish munched prey whole. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: placoderms, Devonian, Gogo Formation, jaw evolution, finite element analysis, hard-object feeding, palaeontology, Flinders University, vertebrate evolution, fossil fish, predator-prey relationships, ancient reefs

Lissamphibians, which encompass modern amphibians such as frogs, salamanders, and caecilians, have retained relatively small body sizes throughout their evolutionary history. Their weights range narrowly from just a few grams to roughly 10.8 kilograms. This striking size limitation is likely connected to the unique architecture of their respiratory system, relying heavily on cutaneous (skin-based) gas exchange alongside buccal pumping—a method where air is actively moved into the lungs by movements of the mouth cavity. While highly effective in aquatic or moist environments, this respiratory strategy is inherently constrained on land due to inefficient carbon dioxide elimination. The slower diffusion rates of CO₂ through skin surfaces necessitate a high surface area-to-volume ratio, favoring smaller body sizes to optimize gas exchange and maintain homeostasis.

Conversely, amniotes—including mammals, reptiles, and birds—display an extraordinary range of body masses, from a mere 0.2 grams in tiny lizards to an astounding 180,000 metric tons represented by extinct sauropod dinosaurs. This group’s success and ecological dominance since the Early Permian period—around 299 million years ago—are largely attributed to their advanced respiratory system. Amniotes evolved costal lung ventilation, wherein ribcage movements actively expand and contract the lungs, facilitating efficient air flow and rapid CO₂ removal. This mechanism significantly reduces the physiological constraints on body size by improving respiratory efficacy, enabling larger body masses and greater metabolic demands.

Central to current hypotheses on vertebrate terrestrialization is the proposed association between the evolution of respiratory mechanisms and body size diversification. The idea that costal lung ventilation freed amniotes from evolutionary constraints restricting body size has long been suggested but remained difficult to substantiate through empirical data. Addressing this gap, a team at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, conducted a comprehensive investigation leveraging an extensive dataset of 344 fossil species dating from the Middle Devonian to the Early Permian—spanning the critical window of vertebrate transition from water to land.

Their study employed evolutionary model fitting to analyze changes in body size, skull morphology, and respiratory traits with unprecedented resolution. The results revealed that both amniote and lissamphibian stem lineages independently moved toward smaller body sizes following a large-bodied common ancestor. However, lissamphibian precursors exhibited much stronger constraints in this downsizing process, reflecting the limitations imposed by their ancestral buccal lung ventilation and dependence on cutaneous respiration. Meanwhile, amniote-lineage vertebrates experienced a relaxation of size constraints, evolving to surpass previous maximum size thresholds as their respiratory system advanced.

Notably, the research corroborates that buccal lung ventilation was indeed the ancestral respiratory mode for all early land vertebrates, inherited by lissamphibian ancestors. The hallmark characteristics of costal lung ventilation—such as ribs exhibiting curvature along the mesiodistal axis and elongated cervical vertebrae—emerged early in the stem amniote lineage. These morphological adaptations suggest that the progenitors of modern reptiles and mammals had already developed more sophisticated ventilatory mechanics, integral to their success in terrestrial habitats.

This evolutionary divergence in respiratory mode had profound physiological consequences. Lissamphibian ancestors retained buccal pumping and increased reliance on CO₂ excretion through the skin, anchoring them to a strategy that inherently favors small body sizes. By contrast, the adoption of costal lung ventilation in amniotes not only allowed for larger bodies but also led to secondary morphological innovations, particularly in cranial architecture. Freed from the functional constraints imposed by buccal pumping, amniotes developed deeper skulls that facilitated the functional partitioning of jaw musculature. This anatomical refinement enhanced static pressure capabilities during tooth occlusion, an essential prerequisite for herbivory.

The emergence of herbivory within amniote lineages was a game-changing event, opening access to new ecological niches through the ability to process plant matter efficiently. As a result, various herbivorous and predatory amniote groups expanded in body size and ecological complexity during the Early Permian, marking a critical phase in shaping terrestrial ecosystems. These dietary shifts, coupled with respiratory and morphological adaptations, underscore the tight interplay between physiology, environmental exploitation, and evolutionary trajectories.

Today, these ancient physiological and morphological legacies are clearly reflected in the disparity of body sizes and ecological roles observed in living terrestrial vertebrates. While amniotes encompass everything from diminutive lizards weighing mere grams to massive elephants and whales, lissamphibians remain strongly predisposed to small sizes due to their cutaneous respiration-based gas exchange. This constraint limits their capacity for ecological diversification and large body size compared to amniotes, echoing patterns established hundreds of millions of years ago.

The findings from this groundbreaking study provide compelling evidence that the decoupling of phenotypic constraints linked to respiratory adaptations fundamentally shaped the divergent evolutionary pathways of the two major land vertebrate clades. Such deep evolutionary divergences laid down the structural and physiological frameworks of modern terrestrial vertebrate communities long before the extensive diversification of extant species. By illuminating the respiratory and morphological innovations that underpinned body size evolution, this research enhances our understanding of the complex drivers behind vertebrate adaptation to land environments.

In summary, the research by Yilun Yu and colleagues bridges a crucial gap in evolutionary biology, demonstrating how respiratory strategies influenced body size limits and ecological potential among early terrestrial vertebrates. Their work not only elucidates the origins of key vertebrate adaptations but also situates respiratory evolution as a foundational axis around which the grand diversification of land vertebrates unfolded. This study highlights the integral role of physiological innovations in overcoming environmental challenges and enabling the vast disparity observable among today’s terrestrial animals.

As amniotes continue to dominate terrestrial ecosystems, it is clear that their evolutionary success traces back to ancient, finely tuned respiratory adaptations. Meanwhile, lissamphibians remain emblematic of the constraints inherited from their aquatic ancestors. Together, these lineages tell a compelling story of adaptation, constraint, and opportunity during life’s monumental transition from water to land.

Subject of Research: Evolution of body size, skull shape, and respiratory traits in early land vertebrates during terrestrialization

Article Title: Decoupled phenotypic constraints framed by respiratory adaptation in the rise of land vertebrates

News Publication Date: 1-April-2026

Web References: https://doi.org/10.1126/sciadv.aeb0801

Image Credits: Image by YU Yilun et al.

Keywords: Evolution, Paleontology, Vertebrate terrestrialization, Body size evolution, Respiratory adaptation, Amniotes, Lissamphibians, Costal lung ventilation, Buccal pumping, Cutaneous gas exchange

Lungfishes are an especially significant group in evolutionary biology due to their close phylogenetic relationship with tetrapods, a lineage encompassing all vertebrates that possess limbs, including amphibians, reptiles, birds, mammals, and ultimately humans. By decoding lungfish anatomy, particularly through fossils combined with advanced imaging techniques, researchers can glean critical insights into the anatomical transformations that underpinned the monumental transition from aquatic to terrestrial life.

One groundbreaking study from Flinders University and its partners focuses on the Late Devonian Gogo Formation in northwestern Western Australia—a globally renowned fossil site renowned for its exceptional preservation of Devonian fish. This study embraces cutting-edge methods such as computed tomography (CT) scanning to reconstruct and analyze the internal structure of enigmatic lungfish fossils that have long puzzled paleontologists.

Among the specimens scrutinized is a particularly damaged fossil, once considered so perplexing that the initial description suggested it might represent an entirely new fish type unknown to science. Employing sophisticated imaging, researchers developed comprehensive digital models of both the exterior and internal cranial anatomy, revealing intricate details of the braincase and inner ear structures with unprecedented clarity. This nuanced approach allowed corrections of earlier morphological interpretations that had mistakenly inverted or reversed anatomical features.

The digital reconstructions also facilitated comparisons with other contemporaneous lungfish specimens from the Gogo site, enabling the establishment of novel anatomical data points. This contributes to a more refined understanding of how these early sarcopterygians (lobe-finned fishes) evolved their distinctive features across Gondwana—an ancient supercontinent comprising present-day Australia, Africa, South America, Antarctica, and India—as well as in other global contexts.

Meanwhile, parallel research in China has substantially expanded the paleontological record of early lungfish evolution with the description of a new species, Paleolopus yunnanensis, from approximately 410-million-year-old deposits in southern China’s Yunnan Province. Unearthed through collaboration between Flinders University researchers and the Chinese Academy of Sciences, this fossil skull sheds vital light on lungfish morphology during a critical window between their initial emergence and subsequent diversification throughout the Devonian period.

Paleolopus exhibits a fascinating combination of primitive and derived traits, showcasing features that foreshadow the feeding adaptations lungfishes retained for hundreds of millions of years thereafter. This discovery bridges gaps in the lungfish fossil record by complementing earlier finds such as Diabolepis, regarded as the most primitive known lungfish, and other species like Uranolophus from North America and Dipnorhynchus from Australian Devonian strata.

Dr. Brian Choo of Flinders University emphasizes the importance of this specimen, noting that it captures a “snapshot” of rapid evolutionary change occurring roughly midway through the Devonian, a time when lungfish were beginning to manifest traits that would define their lineage. The remarkable preservation of the skull offers morphological details of the feeding apparatus and cranial anatomy that underpin vital phylogenetic hypotheses.

This synthesis of Australian and Chinese studies underscores a remarkable global perspective on early vertebrate evolution, illustrating how geological and climatic differences across regions influenced lungfish diversification. Advanced imaging technologies, including high-resolution computed tomography and synchrotron visualization, have been instrumental in these achievements by enabling non-destructive internal examinations of fragile fossils.

Moreover, the research highlights the continued scientific potential residing in under-explored or previously misinterpreted fossil specimens. Revisiting these ancient archives with improved techniques opens fresh avenues for understanding evolutionary processes that shaped complex vertebrate systems. The collaboration among international teams also exemplifies the integrative approach necessary to decode deep time biological narratives.

Significantly, these findings do not only enrich the fossil record but also contribute essential perspectives about the evolutionary innovations that heralded the conquest of land by vertebrates. The anatomical characteristics illuminated in early lungfishes reflect the morphological groundwork for terrestrial adaptations that would eventually lead to amphibians and beyond.

These studies were published in leading scientific journals: the Canadian Journal of Zoology presented the research on the Gogo Formation specimen, while Current Biology featured the discovery of Paleolopus yunnanensis. Both papers underscore the utility of technological advances in imaging to refine paleontological interpretations and strengthen fossil-based evolutionary hypotheses.

Funding and support from the Australian Research Council and the National Natural Science Foundation of China played crucial roles in facilitating these projects. Researchers also acknowledge the Gooniyandi community of Western Australia for granting access and sharing knowledge, reflecting the importance of indigenous partnerships in scientific endeavors.

As ancient lungfishes continue to reveal their secrets, these landmark studies propel the discipline toward a richer, more detailed comprehension of vertebrate ancestry. The evolutionary journey from finned fishes to limbed terrestrial animals remains one of biology’s most captivating stories, progressively pieced together with each fossil unearthed and each scan performed, bridging hundreds of millions of years in Earth’s biological saga.

Subject of Research: Animals (Primitive Lungfishes)

Article Title: Deciphering Cainocara enigma from the Late Devonian Gogo Formation, Australia

News Publication Date: 28-Jan-2026

Web References:

• Canadian Journal of Zoology: http://dx.doi.org/10.1139/cjz-2025-0109
• Current Biology article on Paleolopus: https://www.sciencedirect.com/science/article/pii/S0960982225015398

References:

• Thiele, H.S., Long, J.A., Bevitt, J.J., & Clement, A.M. (2026). Deciphering Cainocara enigma from the Late Devonian Gogo Formation, Australia. Canadian Journal of Zoology. DOI: 10.1139/cjz-2025-0109
• Qiao, T., Cui, X., Zhao, W., Lu, C., Li, M., Lu, J., Choo, B., & Zhu, M. (2025). A new fossil fish sheds light on the rapid evolution of early lungfishes. Current Biology. DOI: 10.1016/j.cub.2025.11.032

Image Credits: Brian Choo (Flinders University)

Keywords: Ancient Lungfish, Devonian Period, Gogo Formation, Paleolopus yunnanensis, CT Scanning, Vertebrate Evolution, Tetrapod Ancestors, Fossil Imaging, Sarcopterygii, Paleoanthropology, Marine Biodiversity, Evolutionary Biology