The Princeton Encyclopedia of Dinosaurs: Sauropods

This is the most comprehensive popular dinosaur encyclopaedia I have yet encountered, describing well over 1100 species and covering mountains of primary literature. Combining a pleasingly uncluttered visual presentation with entries that strike a fine balance between the accessible and the scholarly, this is a reference I can see myself returning to regularly for a pithy overview of almost every dinosaur under the sun. Interestingly, the authors are new to me, and I could find little information about them online. Jones, a science writer and educator, is a self-professed "lifelong dinosaur enthusiast" (p. 9/10). Viola is a chemist who, for the last decade, has dedicated his spare time to illustrating over 2500 extinct animals on DeviantArt.

This set consists of three A4 hardbacks, totalling around 6 kg and over 1300 pages worth of dinosaurs. They are standalone volumes that can be read in no particular order. Each opens with the same eight pages (preface, FAQ, glossary, timeline, deep time, palaeogeography, instructions on usage), which is mercifully brief and minimises repetition between the different books. Each book is then divided into 14 to 21 sections to different families, opening with a detailed family tree and a one-page introduction to the various hypotheses regarding internal relationships and overall organisation of each family. Jones is upfront about the fact that there is no universal agreement amongst palaeontologists on these matters, and has here tried to compile different versions and different interpretations. None of this is presented, nor intended to be taken, as gospel. Nevertheless, I think they admirably condense complex information without dumbing it down.

The bulk of the encyclopaedia is the species profiles, and I think this is where the books shine. Most profiles take up a full page. They show Viola's life reconstruction and basic stats across the top third, the presentation borrowing heavily from the 2020 Dinosaur Facts and Figures books, except using greyscale iconography in standardised positions. It makes for a far cleaner and less cluttered presentation. The bottom-third shows an indented classification list, two maps of fossil localities (one modern, one palaeo, which is a nifty feature), and a small skeletal diagram. This combines all the described specimens to indicate how much of the skeleton we have found. Jones adds that these diagrams are not intended to be anatomically exact; the work of Paul and others remains unsurpassed in that respect.

These infographics sandwich the text. Jones has set himself the challenge of explicitly answering three questions in each profile. 1) What makes each species unique? 2) How are species related to each other? 3) How many fossils do we have of each dinosaur? As he explains, all are surprisingly tricky to answer because 1) You have to trawl through "mountains of highly technical, ultradetailed anatomical descriptions" (p. 9/10); 2) there is virtually no species for which there is universal agreement about relationships, and a lot of ink is spilt on discussing different viewpoints and scenarios and how they have shifted over time; 3) there are large gaps in our knowledge. Many papers, especially older ones, do not illustrate or describe all bones. Elsewhere, information technically exists, but it can be decades before a professional has the time and resources to prepare and describe.

Finally, each volume ends with lists of nomina dubia, informally named species, and tables of museum specimens. Bibliographies are available online and consist of three PDF files spanning 446 pages, though they are double-spaced and include duplicates. They show Jones has consulted a vast body of mostly journal papers (in multiple languages), books, conference abstracts, and PhD theses up to May 2025, by my reckoning.

So much for the description; what of my opinion? Simply put, I think this is an awesome beast. Many popular encyclopaedias claim to be the ultimate one, but this has to be the most exhaustive one, covering well over 1100 species, including many for which we have only bone fragments. This might divide readers, and Paul's decision to limit his field guide to the ~800 better-known might be considered more meaningful. My complaint was that his book left my curiosity about many others unsatisfied, so Jones delivers on this front.

The species profiles neatly address all three questions in a short narrative that retains an impressive amount of nuance and circumspection about how firm or questionable certain findings are. However, what about authority and reliability, given that Jones is not a professional palaeontologist? Comparisons with more technical encyclopedias show him giving fair summaries. This is not surprising, as he references these books and draws on the same primary literature. Similarly, his summaries compare favourably to recent works on specific groups that I have reviewed, though he mostly cites primary literature rather than popular books.

Probably the most divisive aspect of the books is Viola's reconstructions, specifically his decision to make a full life reconstruction of *every*, *single*, *species*, no matter how fragmentary and incomplete their remains. Paul has a strict policy in that regard, only reconstructing those species where he is convinced that further discoveries will not significantly alter our understanding. Though Jones is upfront about their approach in the introduction and uses several indicators in each profile, I worry that—such is the power of imagery—a casual perusal of these books might leave you with the impression that we know exactly what all these animals looked like. Keep in mind that many of the life reconstructions here range from fairly to very speculative.

Though I noticed a few editorial errors beyond the occasional typos, I thought there were surprisingly few given the scale of this project. Recent developments (e.g. Nanotyrannus) have outpaced the book, but to blame it for that is to misunderstand the time frames involved in completing a large book project.

Finally, who is the intended audience? For young readers, the numerous discussions about phylogenetics and group membership might be too abstruse, but I think that for the large audience of adult dinosaur enthusiasts, this book scratches a serious itch. The combination of an uncluttered visual presentation, the compact but informative descriptions, and the extensive coverage that leaves no museum drawer unopened makes this the most comprehensive popular dinosaur encyclopaedia currently on the market. I really enjoyed Jones's potted descriptions and can see myself returning to these books in the future to get me started on any one species, especially as he references an impressive amount of literature.