Reviewed by James O. Farlow (Purdue University Fort Wayne)
Nabavizadeh, A. and D. B. Weishampel. 2023. An Illustrated Guide to Dinosaur Feeding Biology. Johns Hopkins University Press, Baltimore, Maryland, 353 pp. ($44.96 cloth/e-book with 25% PS discount.)
When I was a kid, I was a big fan of comic books that featured dinosaurs. The goofiest of these was Star Spangled War Stories, which supposed that during World War II there was a “War That Time Forgot” in which American GIs were routinely landing on islands and other places still inhabited by dinosaurs and other prehistoric creatures. All of these theropods, sauropods, ornithopods, stegosaurs, ankylosaurs, ceratopsians, pterosaurs, plesiosaurs, and mosasaurs, as well as other creatures of uncertain kind, were uniformly savage beasts, attacking our servicemen at first sight, presumably with trophic intent. Fortunately, our guys were able to blast the monsters away with guns, grenades, tanks, planes, or submarines.
Had it been around back then, the new book by Nabavisadeh and Weishampel might have prompted more restraint on the part of the comic book writers about the prandial proclivities of their dinosaurs. Not all dinosaurs—not even most dinosaurs—were bloodthirsty carnivores. Dinosaur paleontologists already know this, of course, but this book will be valuable to them, as well. It provides an entry into, and a review of, a substantial literature.
Chapter 1 is a brief history of interpretations of dinosaur feeding, and some of the key researchers who contributed to this work. Although trace fossils like bite marks, gut contents (cololites) and ex-gut contents (coprolites) provide explicit records of dinosaur meals, such evidence obviously is not available for all of the meals eaten by the individual animals that produced them, and certainly not for all individuals of a particular dinosaur species. Furthermore, only for cololites is there unambiguous direct association with the specific kind of diner. Consequently, most interpretations of dinosaur diets are inferences derived from analyses of how the jaws and teeth of the animals are constructed, the forces they were able to exert, and the stresses that they were able to withstand, along with interpretations of wear surfaces on teeth, and consideration of features of the postcranial skeleton plausibly related to food acquisition.
Chapter 2, therefore, provides an introduction to the functional morphology of dinosaur bones, joints, and teeth, and the ways that the muscles that worked the jaws are reconstructed. The last of these topics introduces the terminology used to describe muscle structure, and the ways that movements of skull and jaw bones generated by muscle contraction are analyzed. Chapter 3 is a general account of dinosaur skeletal anatomy, obviously with special emphasis on features of the bones of the skull and jaws, the muscles that attached to and moved those skeletal units, and the teeth that were the agents that most directly contacted food items. Both of these chapters will be very helpful for beginners in this area of research, and a succinct review for specialists.
Throughout the book, as its title indicates, there are copious figures: “one great passion we (both authors of this book) share is the love of illustration to investigate and visualize anatomy and function…As dinosaur paleontologists who also illustrate, we have realized that drawing the bones that are sitting in front of us is an exceptional way to learn how to pay close attention to their minute detail. Each bump, groove, ridge, and hole is important to document and measure, both when writing a description of a specimen as well as when trying to assess its complex anatomy in its entirety and when trying to reconstruct the soft tissue anatomy surrounding the bones” (p. 24). Illustrations include black and white drawings of bones, joints, and teeth; color photographs of skulls and jaws, and of entire skeletons; color reconstructions of skulls, jaws, and postcranial musculature; and life restorations of dinosaurs, especially their heads.
The heart of the book is chapters 4–13, which assesses the likely food habits of various dinosaur clades: early dinosaurs and non-tetanuran theropods; early tetanurans, spinosaurs, and allosaurs; early coelurosaurs and tyrannosaurs; maniraptoriform theropods; early sauropodomorphs and basal sauropods; neosauropods; heterodontosaurs and early thyreophorans; eurypodans; early neornithischians and ornithopods; and cerapodans. Carnivorous and herbivorous dinosaurs get about the same number of pages of coverage.
Subsequent chapters follow a common format, which I consider one of the book’s strengths. Each chapter begins with a phylogeny of the group, and a list of genera within that group that are discussed in the text. Then come descriptions of skull and jaw morphology accompanied by color photographs of the skull and jaws in side view, with very helpful labels of diagnostic and other relevant features: openings (foramina), important processes, and regions of muscle attachments. (A few of the photographs [Figs. 5.2, 5.8b, 7.11b, and 11.8b] are a bit dark, however, making some of the labeled features hard to see.) I was particularly pleased to see that figure captions indicate the head lengths. Most of these photographs are accompanied by full-color life restorations of the head of the animal. As charming as these last portraits are, I frequently wished that there were fewer of them, and perhaps instead at least a few photographs of the skull in palatal view. Frequently, there are black-and-white drawings of particularly important bones, joints, and teeth.
This descriptive material is followed by interpretations of the musculature of the skull and jaws, with color reconstructions of cranial musculature in lateral view. This leads to functional morphological interpretations of how the skull and jaws worked: how much force they could exert, the direction of movement of the jaws against the cranium, whether the skull experienced kinesis, and if so, where, and what stresses the skull and jaws could or could not resist. Tooth shapes and wear surfaces are considered, as appropriate. Sometimes authors of cited studies have varying opinions about these matters, with which the authors of the book do not always agree, but evaluations of contrasting ideas about skull and jaw function are always made fairly and respectfully.
Then come descriptions of postcranial skeletal morphology and musculature, in terms of how these features would have affected where and how the dinosaurs foraged and fed. How did the animals move: as bipeds, quadrupeds or perhaps both? For herbivores, are the necks short or long, and how high above the ground could the head be held? For predatory theropods, were these dinosaurs large or small, and fast runners or mainly walkers, and how could the neck musculature assist the skull in removing chunks of meat from a victim’s body? Other lines of evidence—including bite marks, fossilized gut contents and scat, and stable isotope chemistry—are brought to bear when available. After considering all of these lines of evidence, the authors make their best summary inferences about what the most important food items of a particular group of dinosaurs were, and how and where such meals were procured.
The final chapter looks at the “big picture” of dinosaur feeding biology over the course of the Mesozoic. Which groups of dinosaurian herbivores lived at the same time, and in the same places, with which groups of predators, and how may they have interacted? The authors are especially interested in plant-eating dinosaurs, and a final section of the chapter considers the changing composition of herbivorous dinosaur communities over time, in terms of whether the plant-eaters were large (even huge)-bodied or small, generalists or selective feeders, consumers of relative soft or coarse vegetation (and what kinds of plants), and feeding close to the ground or high in treetops—and how all this contributed to coexistence of a diversity of herbivorous dinosaur species in particular communities.
The topics treated by the authors have fascinated me ever since, to borrow a phrase from St. Paul, I put away childish imaginings about dinosaurs—like vicious attacks they might make on soldiers stranded on “lost” Pacific islands—to think about dinosaurs as real, living animals. (Well…I haven’t completely forsaken childish things: I still like Godzilla). This book was a pleasure to read, both reminding me of work about which I previously knew, and exposing me to new studies and ideas I hadn’t yet heard about. I highly recommend it.