The Silver Jaguar is the twentieth treasure that can be found in Uncharted: Drake's Fortune.
The Silver Jaguar is found in Chapter 5 - The Fortress. This cool cat is not too far from the Strange Relic. After getting the Strange Relic, run toward the large pile of rubble and stone as shown in the picture. Find your way over this pile of rock, and head toward the last watchtower (the structures that look out to the ocean). The treasure will be inside there.