Fossils of a new species of a small-car-sized salamander suggest that the amphibians of today have larger and formidable ancestors.

The fossils, which belong to the species Metoposaurus algarvensis, were estimated to be more than 220 million years old and were discovered in an ancient lake bed in Portugal.

"Most modern amphibians are pretty tiny and harmless. But back in the Triassic, these giant predators would have made lakes and rivers pretty scary places to be," said Richard Butler from the University of Birmingham in the United Kingdom.

The distant relatives of this now extinct group of large amphibians include small salamanders, frogs and newts, but the beast is believed to have lived like modern-day crocodiles that feed on fish.

Stephen Brusatte, a paleontologist from the University of Edinburgh, who is part of the research team, said that the creature was a top predator during the period when dinosaurs first evolved and were on their way to dominance.

Most of the animal's big jaws were likely used for munching fish. These early amphibians were not also able to go far from water. Brusatte said that the Metoposaurus would have been a big threat to early mammals or dinosaurs that got too close.

"These big amphibians were some of the main predators and denizens of that world. So our earliest ancestors and the earliest dinosaurs would have had to deal with these guys in their formative years," Brusatte said.

The amphibian had a big broad skull and sported hundreds of sharp teeth. When the animal's jaws were snapped shut, its head looked like a toilet seat. Its skull, on the other hand, was circular in shape with thin flat upper and lower jaws. The creature also had puny arms and legs so it was unlikely able to move around much on land and would have spent most of its time in the water.

It appears that the Metoposaurus was sensitive to climate changes, and researchers believe that many died at the site in Portugal when the lake that these animals inhabited dried up.

"The new Portuguese bonebed provides further evidence that metoposaurids congregated in fluvial and lacustrine settings across their geographic range and often succumbed to mass death events," the researchers reported.

Some 201 million years ago, a mass extinction event occurred, wiping out big amphibians such as the Metoposaurus. The event paved the way for the dinosaurs rising to become the number one predators on Earth.