The Gambian Pouch Rat is the largest rat in the world according many sources. The true is that it is rather the biggest rat-like creature, because the nutria is double in size and that rat is not true rat. He can grow up to 3 or 4 kg. The creature on the picture is may be him smaller cousin - the Emin's rat, I am don't sure. Here we have also funny video where we can see how smart they can be.