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

Around 250 million years ago, the Kimberley region of Western Australia, now a dry and remote landscape, looked dramatically different. Where today there are arid plains and cattle ranches, a shallow, warm tropical bay once stretched, teeming with crocodile-like predators.

The rediscovery of fossils from ancient marine amphibians dating back to the Early Triassic period is revealing a compelling story of life’s recovery following the largest mass extinction event in Earth’s history—the conclude-Permian extinction. Understanding how life rebounded from such catastrophic events offers valuable insight into the resilience of ecosystems and the potential impacts of modern environmental changes.

Rising from a Global Disaster

Approximately 252 million years ago, Earth experienced an event known as the end-Permian mass extinction. This event was triggered by extreme global warming and massive environmental shifts that devastated both marine and terrestrial ecosystems.

According to Dr. Benjamin Kear of the Swedish Museum of Natural History and his team, “The devastating end-Permian mass extinction and extreme global warming triggered the emergence of modern marine ecosystems in the early age of dinosaurs (the Mesozoic Era).”

He added, “This important evolutionary event involved the first appearance of marine tetrapods—vertebrates with limbs—including amphibians and reptiles, which quickly became aquatic apex predators.”

For decades, most fossils of these early “sea monsters” 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.

A 50-Year Mystery of Missing Fossils

The fossils at the center of the modern findings were initially collected during scientific expeditions in the 1960s and 1970s at Noonkanbah cattle station, east of the remote town of Derby in Kimberley. The remains of an amphibian skull buried in ancient coastal rocks 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 Erythrobatrachus fossils mysteriously disappeared over the following 50 years.

Rather than ending the story, the loss prompted a large-scale 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.

Two Predators, One Bay

Erythrobatrachus belongs to a group called trematosaurid temnospondyls, ancient amphibians that superficially resemble crocodiles but are more closely related to modern salamanders and frogs. The creatures could grow up to two meters in length.

Researchers explained, “Trematosaurids are relatives of modern salamanders and frogs that looked like crocodiles and could grow up to 2 meters long.”

This group is significant because its fossils were found in coastal rock layers formed less than one million years after the end-Permian mass extinction. This makes them among the oldest known Mesozoic marine tetrapods that can be geologically identified. The discovery provides crucial evidence for understanding the early recovery of life after a major extinction event and the evolution of marine ecosystems.