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<\/a><\/p>\nThe ancient marine amphibians Erythrobatrachus (foreground) and Aphaneramma (background) swimming along the coast of what is now far norther Western Australia 250 million years ago. Image credit: Pollyanna von Knorring, Swedish Museum of Natural History.<\/p>\n
\u201cThe cataclysmic end-Permian mass extinction and extreme global warming prompted the emergence of modern marine ecosystems at the beginning of the Age of Dinosaurs (Mesozoic Era), some 252 million years ago,\u201d Dr. Benjamin Kear from the Swedish Museum of Natural History and his colleagues said in a statement.<\/p>\n
\u201cThis landmark evolutionary event involved the earliest appearances of sea-going tetrapods (limbed vertebrates), including both amphibians and reptiles, which quickly rose to dominance as aquatic apex-predators.\u201d<\/p>\n
\u201cTo date, the fossils of these earliest sea monsters have been largely documented from the northern hemisphere.\u201d<\/p>\n
\u201cBy comparison, southern hemisphere records are geographically sparse and incompletely known.\u201d<\/p>\n
In their new study, the paleontologists analyzed the fossils of marine amphibians from the iconic Kimberly region of far northern Western Australia.<\/p>\n
\u201cThese fossils were initially discovered in Australia during scientific expeditions undertaken in the early 1960s and 1970s,\u201d the researchers said.<\/p>\n
\u201cThe recovered specimens were distributed between museum collections in Australia and the United States.\u201d<\/p>\n
\u201cThe resulting research was finally published in 1972, and identified a single species of marine amphibian, Erythrobatrachus noonkanbahensis<\/a>, named from several skull fragments found weathering out of a rock outcrop on Noonkanbah cattle station east of the isolated Kimberly township of Derby.\u201d<\/p>\n \u201cUnfortunately, the original fossils of Erythrobatrachus were lost sometime during the intervening 50 years.\u201d<\/p>\n \u201cThis launched a search through international museum collections, which culminated with the rediscovery and reassessment of these enigmatic ancient marine amphibian remains in 2024.\u201d<\/p>\n According to the scientists, Erythrobatrachus was a trematosaurid temnospondyl.<\/p>\n \u201cThe trematosaurids were superficially \u2018crocodile-like\u2019 relatives of modern salamanders and frogs that grew up to 2 m (6.6 feet) in length,\u201d they said.<\/p>\n \u201cThey are important because their fossils occur in rock deposits laid down as sediment in coastal settings from less than one million years after the end-Permian mass extinction.\u201d<\/p>\n \u201cThey are, therefore, the geologically oldest currently recognizable group of Mesozoic marine tetrapods.\u201d<\/p>\n Surprisingly, however, the detailed study showed that the skull fragments of Erythrobatrachus did not all belong to a single species.<\/p>\n Rather, they represented at least two distinct types of trematosaurids: Erythrobatrachus and another species attributable to the well-known genus Aphaneramma<\/a>.<\/p>\n \u201cExamination of the Erythrobatrachus skull using high-resolution 3D imaging suggests that it was about 40 cm (16 inches) long when complete, and came from a large-bodied, broader-headed top-predator,\u201d the authors said.<\/p>\n \u201cOn the other hand, Aphaneramma was about the same size but had a long thin snout for catching small fish.\u201d<\/p>\n \u201cBoth of these trematosaurids swam through the water column, but would have hunted different prey in the same habitat.\u201d<\/p>\n \u201cFurthermore, while Erythrobatrachus in known exclusively from Australia, fossils of Aphaneramma have been reported from similar aged deposits on Svalbard in the Scandinavian Arctic, the Far East, Pakistan and Madagascar.\u201d<\/p>\n \u201cThe Australian trematosaurid remains thus show that these earliest Mesozoic marine tetrapods not only radiated rapidly into a range of ecological niches, but also managed to disperse worldwide, perhaps following the coastal margins of interconnected supercontinents during the first two million years of the Age of Dinosaurs.\u201d<\/p>\n