I liked the look of this film but had never heard of it before. With good reason, accoriding to the reviewer on IMDB. It's crap. Written by 50s sci-fi/monster movie superemo Curt Siodmak, it is also directed by him and it would seem he did a rotten job. Although it's filmed on location in Brazil, the effects are rubbish and the actors more wooden than the rainforest.
I'm intrigued, though, that it it appears to be based on a genuine crytozoological mystery. Richard Freeman wrote about weird beasts of Brazil in Paranormal Magazine issue 43 and mentions the Mapinguari, which the local people describe as being a huge furry critter with long curving claws, an armoured hide and a loud roar. Its footprints appear to point backwards, they say. Oddly enough it's this latter detail that makes it more convincing as real rather than imaginary, because fossil footprints of the giant sloth (mylodon) do look as if they're facing the wrong way, and Mapinguari does sound very like a mylodon, an animal that was prevalent in South America thousands of years ago. The giant sloth also had knobs of bone under its skin, which would serve as a kind of chain armour.
Does a species of the animal still survive in the depths of the Amazon Rainforest? Who knows. But at any rate, 'Curucu' sounds very like the Mapinguari and one can only assume that somehow Siodmak had heard of it. The film was made in 1956 and isn't available on video/DVD.