Invertebrate Palaeontology & Evolution by Clarkson which is a beautiful textbook yet still accessible to the laymen since it is written for undergraduates.
Introduction to Paleobiology and the Fossil Record by Benton and Harper is the best introduction to paleontology in general you can get, and may be worth a look if you are having trouble with the other books make.
A lot of searches will point you to Life: A Natural History of the First Four Billion Years of Life on Earth It is OK but the author very much has their storytelling hat on. Great for making it a more enjoyable read, bad if you want information. It reads more like a biography.