This is the first book in a trilogy. However, the author doesn't end with a cliffhanger, but with an apparent resolution to the story. This makes me think the book was well received and sold a lot of copies, so Harrison decided to make it a trilogy. But you can stop with this one if you choose to do so.
A pretty good story once you get over the alternate earth part with it's intelligent reptiles. Harrison once again weaves a story that captures you with the richly developed characters. The genetic expertise of the reptiles is not too far out there I guess. The humans are very engaging. I recommend it!
A very different approach to pre-history. A very entertaining read.
Very good, a classic!