This is a 10" x 9" Matrix Free Oligocene  era  Oreodont Skull from the White River Formation Badlands in South Dakota.  I obtained this from an estate sale.  This is a great piece, it has a great screaming pose.  You catch the moment of agonizing death.  I can't tell if there are any fillers.  There might be a little around the right eye socket.  Please look at the pictures.  A great piece. Ask questions if you have them and thanks for looking!