A Prehistoric Fish in the Russian Pond

Look what they have found in Chelyabinsk city. The story is that there was a construction site with a deep foundation ditch. They have touched some underground river in that place so the water in the ditch didn't get away so it stayed there full of water. Then some workers a few months later spotted some movement in this water, they threw some pieces of their lunch in the trench which caused a big activity inside. They were puzzled who is there? And caught one thing up then in big panic stepped away cause it tried to bite them so they had to kill it with some equipment and here are the remains of it. It was around 5 feet length. Nobody of them got any idea of what's that:

Submitted By: eggeyes