Keeping up with the latest dinosaur discoveries is no easy task. New species are announced at such a rapid rate that it is difficult to keep track of them all, and new analyses of old bones are rapidly changing our understanding of how dinosaurs lived. Given the vibrant state of dinosaur science, any book about them is going to be out-of-date by time it hits the shelves, but Gregory Paul's new Princeton Field Guide to Dinosaurs is a useful yearbook of dinosaurs which includes a variety of rarely-mentioned species.
To call the book a "field guide" is a bit of a misnomer. It is not going to be very helpful while looking for dinosaur fossils, and obviously the only living dinosaurs to be observed are birds (and for them you need a Sibley's guide). Instead it is more of a dinosaur catalog that lists one species after another, although I can understand why it was not called The Catalog of Dinosaurs ("Tyrannosaurus rex is $10,000,000.00 plus shipping").
What die-hard paleo fans are most likely to notice about the book, however, is the name on the cover: Gregory S. Paul. Known for his intricately-detailed artwork and his richly-illustrated book Predatory Dinosaurs of the World, Paul has been instrumental in shaping the image of dinosaurs as we know them today. The new field guide is well-stocked with skeletal drawings, a smattering a life restorations, and a few classic bits of artwork from previous publications. Personally, I think Predatory Dinosaurs of the World still represents Paul's best work in terms of illustration quality and quantity, but I enjoyed seeing skeletal restorations of many new and little-known dinosaurs in the Princeton field guide.
As for the information contained within the field guide itself, it varies from section to section. There book opens with a fairly comprehensive introductory section, and while there were a few parts I disagreed with—such as a nod to the flawed "Dinosauroid" thought experiment—it is still a solid summary of dinosaur basics.
Frustratingly, however, at times Paul uses the book as a platform for his hypothesis that many feathered dinosaurs were the descendants of flying ancestors, an idea that should be treated not as fact but as tentative and awaiting further evidence. He also engages in a bit of creative name rearranging. In many cases Paul lumps several species or genera of dinosaurs into one genus, although the criteria do not appear to be consistent. For example, Paul lumps the significantly different horned dinosaurs Styracosaurus and Pachyrhinosaurus into the genus Centrosaurus, while—as an extension of one of his own recent papers—he splits minutely different dinosaurs previous grouped under Iguanodon into separate genera such as Dollodon and Mantellisaurus. I am not suggesting that Paul had to accept every proposal of his colleagues—writing a book requires a lot of judgment calls—but revising so much dinosaur taxonomy without doing the detailed scientific work will only cause confusion among readers. I would have expected that anything called a "field guide" would be more representative of the general consensus among scientists while noting areas of disagreement.
My frustrations with the book aside, it can be a useful sourcebook for anyone who wants to quickly get up to speed on dinosaur diversity. The dinosaurs we know the most about have the most written about them in the book, but it is still useful to have an illustrated index of dinosaurs which, as we learn more, can act as something of a time capsule to show us what we thought about dinosaurs at this point in history. Indeed, Paul is to be crediting for pulling so much information together into one volume, as well as for illustrating so many skeletons (some dinosaurs no doubt discovered while the book was in press). Used in conjunction with detailed books such as Thomas Holtz's recent encyclopedia, the new Princeton field guide can do much to bring a dino fan's bookshelf up-to-date.