New York: Tor Books, 2001. 352 pages.
From the cover: "An alien shuttle lands outside Toronto's Royal Ontario Museum. A six-legged being emerges, who says, in perfect English, 'Take me to a paleontologist.' It seems that Earth, and the alien's home planet, and the home planet of another alien species traveling on the alien mothership, all experienced the same five cataclysmic events at the same times in their prehistory (one was the asteroid impact that on Earth wiped out the dinosaurs). Both alien races believe this proves the existence of God: God has obviously been playing with the evolution of life on each of these planets. From this provocative launch point, Sawyer tells a fast-paced, and morally and intellectually challenging, SF story that just grows larger and larger in scope."