Are any living trees direct descendants of fossil ancestors?

Yes; most familiar example is gink-go, a native of China that is now cultivated in the United States. The recently discovered "Dawn Redwood" (Metasequoia), also of China, was at first believed to be a "living fossil" but recent indications are that it may be a "surviving ancestor" of the well-known American coast redwood. In 1948, Dr. Ralph Chancy, of the University of California, headed an expedition into China to study the Dawn Redwood and bring back specimens and seed of it. Seedlings and transplants from China are growing at the University of California as a result of his effort. A league for the protection and preservation of these trees in China has been founded and is being encouraged and assisted by the "Save the Redwoods League" of the west coast.