A giant killer newt that "looks like something out of a bad monster movie" was a top predator more than 200 million years ago, scientists have found.
Its fossilised remains - the size of a small car - were found buried at the site of an ancient lake in southern Portugal.
The ferocious amphibian, Metoposaurus algarvensis, is a distant relative of salamanders living today, said scientists.
Edinburgh University's Dr Steve Brusatte, from the School of GeoSciences, led a study of Metoposaurus published in the Journal of Vertebrate Paleontology. He said the newt "was as long as a small car and had hundreds of sharp teeth in its big flat head, which kind of looks like a toilet seat when the jaws snap shut.
He added: "It was the type of fierce predator that the very first dinosaurs had to put up with if they strayed too close to the water, long before the glory days of T. rex and Brachiosaurus."
The family of giant salamander-like amphibians to which Metoposaurus belonged were wiped out during a mass extinction 201 million years ago, long before the death of the dinosaurs.
This event marked the end of the Triassic Period, when the super landmass of Pangaea, which included all the world's present-day continents, began to break apart.
The extinction killed off many groups of vertebrates, including giant amphibians, and paved the way for dinosaurs to take over the Earth.
Members of the Portuguese Metoposaurus colony are thought to have died when the lake they inhabited dried up.
Only a four square metre fraction of the site has been excavated so far, and work is continuing in the hope of unearthing more fossils.
Co-author Dr Richard Butler, from the University of Birmingham, said: "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."