The fossil remains of a giant crocodile that ruled the oceans 140m years ago have been found in Patagonia, Chile.
Scientists have nicknamed the creature Godzilla, because it looks a bit like a dinosaur and has jagged teeth.
A team of experts from the US and Argentina believe the creature was a ferocious predator that munched on other reptiles and large sea animals.
Unlike the crocodiles alive now, it had fins instead of legs and spent all of its time living in the water.
It measured 4m (13ft) from nose to tail and its jaws alone were a third of a metre long.
A scientist takes a closer look at a 'Godzilla' fossil
Computer studies of the fossilised remains show that is was a member of the crocodile family.
It was unlike many other creatures living in the sea at the time, as they had long snouts and small teeth and probably fed on small animals.
The 'Godzilla' croc had a mouth like a dinosaur and big teeth, which suggest it preferred to attack large animals to eat.
The species is formally known as Dakosaurus andiniensis and has been unveiled in the journal Science.