Scientists in Chile have found the fossils of a strange new dinosaur species.
This dog-sized dino had a tail weapon unlike the kind seen on any other animal.
It slashed instead of clubbed or stabbed.
Revealed in a study Wednesday, the dinosaur at first fooled researchers: They thought it was like a stegosaurus.
But it was actually part of a different armored dinosaur family that hadn't been seen much that far south.
Even though it is only distantly related to the stegosaurus, researchers call it stegorous.
The plant-eater lived about 72 million to 75 million years ago.