About 250 million years ago, what is today a scorching desert in remote northwest Australia was the coast of a shallow bay bordering a vast prehistoric ocean. Fossils recovered from the area more than 60 years ago and largely forgotten in museum collections have shed new light on the earliest global radiation of land-dwelling animals adapting to life in the sea.

The mass extinction and extreme global warming of the end-Permian catastrophe prompted the emergence of modern marine ecosystems at the beginning of the Age of Dinosaurs (or Mesozoic Era) about 252 million years ago. This landmark evolutionary event included the early appearance of sea-going tetrapods (limbed vertebrates), including both amphibians and reptiles, which soon became dominant as aquatic apex predators. To date, fossils of these earliest sea monsters have been recorded primarily in the Northern Hemisphere. In comparison, the Southern Hemisphere record is geographically sparse and incompletely known.

A new study of 250 million-year-old fossil remains from the iconic Kimberley region of Western Australia’s far north has revealed evidence of a surprisingly diverse marine amphibian community with unexpected global and transoceanic connections.

find lost fossils

Fossils of ancient marine amphibians were first discovered in Australia during scientific expeditions in the early 1960s and 1970s. The recovered specimens were distributed to museum collections in Australia and the United States. The results of that research were finally published in 1972 and identified a species of marine amphibian. Eryslovatrachus nooncambahensisnamed after several skull fragments found weathered from a rocky outcrop at the Noonkumba cattle station, east of the isolated Kimberley township of Derby.

Unfortunately, the original fossil Eryslovatrachos Lost for 50 years. This began a search for international museum collections, culminating in 2024 with the rediscovery and reassessment of these mysterious ancient marine amphibian remains.

Uncovering mysterious communities and global radiation

Eryslovatrachos It was a temnospondylus of the trematosaurid family. Trematosaurs were superficially “crocodile-like” relatives of modern salamanders and frogs, growing up to two meters long. Trematosaurids are important because their fossil remains come from rock deposits that were deposited in coastal environments less than 1 million years after the end-Permian mass extinction. They are therefore geologically the oldest of the currently recognized groups of Mesozoic marine tetrapods.

But surprisingly, detailed re-study revealed that skull fragments Eryslovatrachos Not all belonged to a single species. Rather, they represented at least two different types of trematosaurids. Eryslovatrachos and another species belonging to a well-known genus Aphaneramma.

inspection of Eryslovatrachos Using high-resolution 3D imaging, the skull was approximately 40 centimeters long when completed, suggesting it was derived from a large-bodied, broad-headed top predator. on the other hand, Aphaneramma They were about the same size, but had elongated snouts for catching small fish. Although both of these trematosaurs swam in the water column, they likely hunted different prey in the same habitat.

moreover, Eryslovatrachos Fossils known only from Australia Aphaneramma It has been reported from similar old deposits in Svalbard in the Scandinavian Arctic, the Russian Far East, Pakistan, and Madagascar. Thus, Australian trematosaurid fossils indicate that these earliest Mesozoic marine tetrapods not only rapidly radiated into a range of ecological niches, but also dispersed around the world along the coastal margins of interconnected supercontinents, probably during the first two million years of the dinosaur era.

The paper is Journal of Vertebrate Paleontology. The rediscovered fossils are Eryslovatracos He is currently being repatriated to Australia. Fossils of other ancient amphibians from the age of dinosaurs are on public display at the Swedish Museum of Natural History.

reference

Kear, B. P., Campione, N. E., Siversson, M., Bazzi, M., Hart, L. J., 2026. Revised trematosaurids Eryslovatrachus nooncambahensis A mysterious marine hand vertebra community inhabiting the Lower Triassic of Western Australia has been confirmed. Journal of Vertebrate Paleontology45(4), e2601224. DOI:10.1080/02724634.2025.2601224

contact address

Benjamin Kear (first author), Swedish Museum of Natural History: benjamin.kear@nrm.se

Disclaimer: AAAS and EurekAlert! We are not responsible for the accuracy of news releases posted on EurekAlert! Use of Information by Contributing Institutions or via the EurekAlert System.