Microraptor - a small dinosaur about 20 inches long. The most unusual thing about this creature was its feathered hind limbs. The long and tapered feathers came from its thighbones and shinbones and made it look like it had four wings.
Spinosaurus may be the larges Theropod to ever stalk the Prehistoric Americas and believed to be even larger than T-Rex. Recently (late it was determined to be the first and only known aquatic dinosaur.