As-is the back of this model is hardly presentable. One option would be to use the sculpt tools from Chapter 7, Teddy Bear Figurine to sculpt the missing parts of the lion. An easier option is to throw a cube behind it to hide the blemishes and call this project a book end:
Add (Shift + A) a Cube.
Scale (S) and Move (G) the cube until it is slightly taller and wider than the statue, and thick enough to hide the back of the lion. Try to be as precise as possible when positioning the bottom of the cube to the bottom of the statue, but don't stress too much about it. The bottom will be re-flattened.
Add a Boolean modifier to the cube.
Union the Lion_Capture object to the cube.
Apply the modification.
Enter Edit Mode (Tab).
In Right side (NumPad 3) view in the Wireframe view (Z), Border Select (B) all the points that make up the bottom of the lion.
Scale (S) along the z axis (Z) by
0units to assure the bottom is perfectly flat.
Exit Edit Mode (Tab).
Before exporting the model, Scale...