Original: Avimimus, meaning "bird mimic" (Latin avis = bird + mimus = mimic), was a genus of bird-like maniraptoran dinosaur that lived in the late Cretaceous in what is now Mongolia, around 70 million years ago.
Simplified: Avimimus (meaning "bird mimic") was a recently-discovered maniraptoran. It was a very fast moving, light-weight, bird-like theropod dinosaur that lived in the late Cretaceous in what is now Mongolia, around 70 million years ago.