This is a 7" x 4" Oreodont Skull from the Oligocene Era.  It is matrix free!  It has all four jaw sections.  Has most of the teeth.  There is a little filler behind the right eye socket and inside the left upper jaw.  The eye sockets are in good shape.  The upper and lower sections are separate.  A person could paste these back together.  Look at the pictures and feel free to ask questions.  This was obtained from an estate sale from the White River Badlands in South Dakota.  Thanks for looking!