Recent findings from museum collections in Australia and the United States showcase the incredible diversity of the Western Australian trematosaurid temnospondyl, underscoring how early marine amphibians proliferated across the continent shortly after the end-Permian mass extinction.
Ancient marine amphibians Erythrobatrachus (foreground) and Aphanelamma (background) traversed the northern coast of modern-day Western Australia 250 million years ago. Image credit: Pollyanna von Knorring, Swedish Museum of Natural History.
“The catastrophic end-Permian mass extinction and severe global warming gave rise to modern marine ecosystems at the dawn of the Mesozoic Era, around 252 million years ago,” stated Dr. Benjamin Kjaer from the Swedish Museum of Natural History and his colleagues.
“This significant evolutionary milestone marked the early emergence of sea-going tetrapods (limbed vertebrates), including amphibians and reptiles that quickly established themselves as dominant aquatic apex predators.”
“To date, the earliest sea monster fossils have primarily been documented in the Northern Hemisphere.”
“In contrast, the fossil record from the Southern Hemisphere remains geographically sparse and inadequately understood.”
Paleontologists recently analyzed marine amphibian fossils from the renowned Kimberley region of Western Australia’s far north.
“These fossils were uncovered during scientific expeditions in the early 1960s and 1970s,” the researchers noted.
“The specimens were subsequently distributed to various museum collections across Australia and the United States.”
“The results of this research were initially published in 1972, identifying a single species of marine amphibian, Erythrobatrachus nooncambahensis, named after skull fragments discovered at Noonkumba Farm, east of Derby in the Kimberley region.”
“Unfortunately, the original fossil of Erythrobatrachus has since been lost over the past 50 years.”
“This prompted a survey of international museum collections, leading to the rediscovery and reanalysis of these ancient marine amphibian remains in 2024.”
According to scientists, Erythrobatrachus is classified within the trematosaurid family of temnospondyls.
“Trematosaurids bore a superficial resemblance to crocodiles and were related to modern salamanders and frogs, reaching lengths of up to 2 meters (6.6 feet),” the researchers explained.
“These fossils hold significant importance as they were found in rocks deposited as coastal sediments less than a million years after the end-Permian mass extinction.”
“Thus, they represent the oldest currently recognized groups of Mesozoic marine tetrapods in geological terms.”
However, detailed investigations revealed that the skull fragments of Erythrobatrachus were not unified but belonged to at least two distinct types of trematosaurids: Erythrobatrachus and another species from the well-known genus Aphanelamma.
“Examination of Erythrobatrachus using advanced 3D imaging indicated the skull measured approximately 40 centimeters (16 inches) when intact, suggesting it was a robust, broad-headed apex predator,” the authors stated.
“Conversely, Aphanelamma were similar in size but featured elongated snouts adapted for catching smaller fish.”
“Both types of trematosaurids occupied the water column yet targeted different prey within the same habitat.”
“Furthermore, the fossils of Erythrobatrachus are uniquely found in Australia, while Aphanelamma has been discovered in similarly aged deposits across regions like the Scandinavian Arctic, Svalbard, the Far East, Pakistan, and Madagascar.”
“The Australian trematosaurid fossils provide evidence that these early Mesozoic marine tetrapods not only radiated swiftly into various ecological niches but also dispersed globally along the coastal margins of interconnected supercontinents during the initial two million years of the dinosaur epoch.”
The team’s study was recently published in the Journal of Vertebrate Paleontology.
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Benjamin P. Care and colleagues. Revision of Trematosauridae Erythrobatrachus nooncambahensis: A mysterious marine vertebrate assemblage from the Lower Triassic of Western Australia. Journal of Vertebrate Paleontology, published online on February 22, 2026. doi: 10.1080/02724634.2025.2601224
Source: www.sci.news
