Who is Brian McCarthy from Dragon Bones: A Novel and what is their importance?

Brian McCarthy is an American archaeological student on a fellowship to China. He discovers a wealth of treasure in a cave, and begins bringing the treasure to Lily Sinclair, a member of a team of auctioneers for Cosgrove's. He also discovers proof of a large fungus, which he sends to his sister, a mycologist. Brian then realizes the treasures he has been taking are those of Yu, and he refuses to tell Michael where the relics are kept. As a result of their fight, Brian is killed.