Foster Alan Dean. Founding of the Commonwealth 3. Diuturnity's Dawn

In the third and concluding novel of this trilogy, an uncomfortable archaeological alliance of Thranx, humans, and AAnn, explores the well-kept secrets of the lost civilization of the Sauun on the frontier world Comagrave. After a series of accidents that occur where the AAnn are convenient for helping an injured or stranded human, the chief Thranx scientist starts suspecting an anti-Thranx conspiracy. Meanwhile on the planet Dawn, such a conspiracy seems to be up and running, for terrorists there plan vicious destruction to crush the infant commonwealth. Unexpected players in this engrossing drama are the padres, human and Thranx, of the anything but dogmatic United Church, which ministers to both species with a decidedly untraditional religious outlook.