Ancient Crocodile-Like Creature Reveals Australia Desert Was Once a Tropical Sea

Fossil remains of ancient marine creatures, unearthed in the remote Kimberley region of Western Australia, are rewriting the understanding of life’s recovery following the Earth’s most devastating extinction event. The fossils, dating back approximately 250 million years to the Early Triassic period, reveal a shallow, tropical bay teeming with predators resembling crocodiles, a stark contrast to the arid, sparsely populated landscape of the Kimberley today.

The discovery sheds light on how life rebounded after the end-Permian mass extinction, triggered by extreme global warming and widespread environmental changes that decimated both marine and terrestrial ecosystems. According to Dr. Benjamin Kear of the Swedish Museum of Natural History, “The devastating end-Permian mass extinction and extreme global warming triggered the emergence of modern marine ecosystems in the early days of the Age of Dinosaurs (Mesozoic Era).” He added, “This pivotal evolutionary event involved the first appearance of marine tetrapods—vertebrates with limbs—including amphibians and reptiles, which rapidly became aquatic apex predators.”

For decades, the majority of early “sea monster” fossils have been found in the Northern Hemisphere. Records from the Southern Hemisphere, including Australia, have been limited and poorly understood. Recent research is beginning to change that picture.

The fossils at the center of the renewed investigation were initially excavated during scientific expeditions in the 1960s and 1970s at Noonkanbah cattle station, east of the remote town of Derby in the Kimberley. The fragmented skull remains of the marine amphibian were then divided between museums in Australia and the United States.

In 1972, scientists published a study identifying a new species based on the skull fragments: Erythrobatrachus noonkanbahensis. However, the original fossils of Erythrobatrachus mysteriously disappeared over the following 50 years. This loss prompted an extensive search of international museum collections. In 2024, researchers successfully located and re-examined the fossils using high-resolution 3D imaging technology.

The results were surprising. Erythrobatrachus belongs to the trematosaurid temnospondyl group, ancient amphibians that superficially resemble crocodiles but are more closely related to modern salamanders and frogs. The creatures could reach up to two meters in length. Scientists explain that trematosaurids are relatives of modern salamanders and frogs that looked like crocodiles and could grow up to 6.5 feet long.

This group is significant given that its fossils were found in coastal rock layers formed less than one million years after the end-Permian mass extinction. This makes them the oldest identifiable Mesozoic marine tetrapod group currently known. The Kimberley region, part of the northernmost of the nine regions of Western Australia, is bordered by the Indian Ocean to the west and the Timor Sea to the north, according to Wikipedia. The region was named in 1879 by Alexander Forrest after John Wodehouse, 1st Earl of Kimberley.

The discovery highlights a previously underappreciated chapter in the recovery of life after a catastrophic event, and underscores the Kimberley region’s importance as a repository of paleontological evidence. Further research is planned to explore additional fossil sites in the area, with the hope of uncovering more clues about the early evolution of marine life.