Move over, "Godzilla." Your nuclear origin story is old and tired. Make room for the sea-dwelling T-Rex in "Poseidon Rex," an upcoming horror movie about underwater dinosaurs, treasure, and the hapless twentysomethings who think that being young and hot will save their expendable little lives. For us, the trailer proves two things: 1. This movie is real, and 2. You can swim pretty well with T-Rex arms.