I happened upon a digital version of the The Princeton Field Guide to Dinosaurs (2nd ed., 2016) in the New School Library collection. The author and illustrator, Gregory S. Paul is a dinosaur illustrator and independent researcher.

As a reference book, the bulk of the text is, as the title suggests, field guide-style listing of known dinosaur species, organized into three main sections: theropods, sauropodomorphs, and ornithischians. While I perused the field guide section of the book, I spent more time reading Paul’s introduction, which provides an overview of current understandings of dinosaur natures. Others have argued that “dinosaur” is now more a folk taxonomy than truly scientific term¹, Paul does spend some time defining dinosaurs. Dinosaurs are tetropods–vertebrates adapted for life on land. Within the superclass of the tetropods are amniota, tetropods that reproduce by laying hard-shelled eggs (some have since evolved to give life birth). Of the amniotes, there are the synapsida (mammals are the only surviving synapsids) and the diapsida, which includes lizards, snakes, crocodilians, and birds. Archosauria is the largest and most successful group of diapsids and includes crocodilians and dinosaurs. “Birds are literally flying dinosaurs” (p. 3). This detailed explanation of just where dinosaurs fit on the animal family tree, including what is (bird) and is not (plesiosaurs, pterodactyl) a dinosaur, suggests that the term “dinosaur” still holds some meaning in scientific understandings of prehistoric animals, whether “dinosaur” is a taxonomic classification in the strictest sense.

The introduction covers a lot, but another discussion I found interesting was contextualizing the evolution and extinction of dinosaurs. Paul describes the time of dinosaurs as both “ancient and surprisingly recent” as a matter of perspective, the notion that the dinosaurs are remote in time really is indicative of humans’ short lifespan. A galactic year, the time it takes for our solar system to orbit the galaxy, is 200 million years — dinosaurs appeared on early only one galactic year ago, and the earth was already 4 billion years old at that time. Paul also explains that “It is difficult to exaggerate how remarkable the loss of the dinosaurs was” (p. 23). Dinosaurs thrived for over 150 million years (modern humans have only been around for 200,000 years). The extinction event at the end of the Cretaceous eliminated all non-avian dinosaurs–a huge, diverse group of animals that comprised all the major land animals at the time.