Do not be fooled by the cute appearances, the T-Rex is a vicious hunter and is following your movements. The T-Rex was built based on the dragon illusion, which freaks your mind into thinking that the eyes are following you.
If we move around when viewing a solid object, our brain knows how the object we are looking at should behave. However the dragon gives us the wrong clues, because we mis-interpret what its shape is. We assume that the nose of the dragon is pointing out towards us, but in fact the dragon’s head is concave.