I didn't really care about it, since I didn't know what I was planning on drawing, so I took it home to think. Going through the non-reserved pages I spotted the last one, in fact, the back of the notebook, a type of cardboard thick brown surface. I thought: Well, nothing marked here. Let me go crazy. And I did.
This Jaguar was done in Colored Pencils, Sepia, Ink and some Dry Pastels. In the end, It wasn't puuuurfect, but, I was pleased. So I took a photo of it and here it is...
I guess the original is still in that sketchbook. God knows where.