July 5, 2013 2:19:54 PM
Let's say you have read the delightful My Beloved Brontosaurus by Brian Switek and you find yourself hankering for more facts and scientific insight. Let's say you remember being enchanted with dinosaurs as a kid and you wonder what you'd be doing now if the rest of life hadn't turned you away from that initial fascination. Let's say you just want to get the latest on what paleontologists are doing. Here's what to do: get The Complete Dinosaur (Indiana University Press), edited by M. K. Brett-Surman, Thomas R. Holtz, Jr., and James O. Farlow, with Bob Walters as art consultant, and written by sixty experts in different subspecialties. The book is as fine and as imposing a volume as any I have seen from a university press. It is enormous, 1,100 big pages and over six pounds in weight. The pages have lovely wide margins often used for illustrations, and there are illustrations aplenty, not just of the amazing beasts, but of their descent trees, bone loading, tracks, bone growth rings, and much more. This is not light reading, in any sense. I could not take the book to bed for nighttime reading, nor even to my recliner. I wound up setting it on one of my weight benches and reading it from an adjacent chair. The chapters are full of detail and the prose is (at least in big chunks) necessarily technical; you will find many sentences like, "Plagued by inconsistent definitions, use, and predictions, it is not always clear whether gigantothermy postulates a convergence of metabolic rates as well as thermoregulatory performance, or whether the supposed metabolic convergence is toward the reptile level, the mammal level, or in between." (The appendices do include a big and useful glossary, as well as a list of dinosaur-related websites.) The forty-five chapters here, however, represent detailed thought, sustained over centuries (and this is the second edition of the book, the first having come out in 2007). The erudition on display, applied to ancient animals that interest everyone, is an inspiration.
The start of the book gives a history of human thought about dinosaurs, showing that fossil discoveries were made by many primitive societies and may have been the source of myths about monsters, griffins, or dragons. It was good luck to turn up such bones when plowing a field. Gobi dinosaur eggs were drilled with neat holes to be strung on necklaces. American Indians thought of the bones as being from "the grandfather of the buffalo," which is here called "a near-scientific interpretation." William Clark, of the Lewis and Clark expedition, found a dinosaur rib near where is now Billings, Montana. Fossil finds were not always considered bones, and when they were, they were originally thought to be of huge fish or elephants. Eventually, Richard Owen, who coined the term "dinosaur," and others were able reliably to represent the animals as distinct from anything now living, although their ideas and pictures of dinosaurs are now quaintly outdated.
If you fantasize about going into the field and uncovering the next T. rex, there are detailed and basic instructions here. (It could happen even if you don't follow the instructions: "Mr. Charlie Fickle found a partial skeleton of the great predatory dinosaur Tyrannosaurus rex while walking his dog at a housing construction site in Littleton, CO.") Get the permission of the landowner and respect the landscape are the first rules. "Dinosaurs are no longer trophies. Instead they are scientific specimens whose context is as important as the bones themselves." Mapping has been made much easier with GPS, but although paleontologists dream of scanning satellite or photographic maps and locating bones that way, such resources can only tell aspects of the surface geology that might predict the likelihood of finds. Similarly, they'd love to have some sort of x-ray that would see bones below the surface, but while there is hope that ground-penetrating radar or seismic data may someday provide such pictures, such an invention is only in the realm of the movies. (In Jurassic Park "... a procedure known as computer-assisted sonic tomography [CAST] was used to do a field sonogram on a buried skeleton of Velociraptor. It worked marvelously, and a whole skeletal outline could be seen. In the real world, however, such technologies do not work quite as well.") Until then, despite how television documentaries show the work, excavation takes lots of labor, time, and planning. Digging tools from bulldozers to jackhammers to powered hand tools to dental picks all may come into play. There is a chapter here on specific modern technology used in the field, like handheld devices to upload notes and descriptions of finds directly into a field office, avoiding much of the confusion from the transcription of field notes (or the theft or loss of field journals). Portable printing devices can provide labels for specimens as soon as they are dug out, labels with extra data about location. Looking inside the bone happens when it is taken back to the lab. It is a delightful surprise to read: "Most medical centers enjoy scanning objects for paleontologists from time to time."
A huge amount of the book deals with just how much information we might draw out of fossils. Muscular tissue is seldom fossilized, but putting flesh on dinosaur bones is essential for understanding what they looked like and how they moved. A chapter here shows how specific muscle attachments in hands, necks, legs, and tails of fossil bones can be detected and understood. ("The presence of cheek muscles in ornithischian dinosaurs has long been debated...") There is even bone evidence for how nerves ran, or infections, or cancers. Bones are not the only things dinosaurs left behind. Rarely, dinosaurs left footprints, and such variables as hip height, print length, or narrowness of separation between left and right prints can be used to calculate speed. Stomach contents, even from herbivores, are sometimes preserved. "Fossilized feces from herbivorous dinosaurs are particularly rare, but large, bona fide coprolites containing abundant plant material can usually be plausibly attributed to dinosaurs, because most other Mesozoic herbivores were too small to have generated much fecal material in one defecation 'event.'" Reflecting on the booming field of investigation of what dinosaurs ate is a message that could apply to many of the other subjects of this book: "There is much here to entertain and frustrate the paleontologists of the future!"
Many familiar dinosaurs get their own chapters here, like the one on stegosaurs. Those back plates have been a puzzle ever since they were first seen. There have been many guesses about what they were for. Someone guessed that the stegosaur could raise the plates from horizontal to vertical, like a cat puts its hair up, to look bigger and more aggressive, but it turns out that there isn't evidence of muscles to make this happen. They could have been armor, but they were not made of protective compact bone. They may have been useful for identification of different individuals, or for sexual display. The best idea is that they helped with regulation of body temperature.
There is so much information here in this enormous book: how different dinosaurs evolved; how they are put up as museum exhibits; their bird descendants; their reproductive biology; and much, much more. I will end with a personal note. Every medical student learns the twelve cranial nerves (along with a more or less silly or ribald mnemonic for their names). If someone had asked me about cranial nerves in other mammals, I would have expected that they'd be there, too. But it was a surprise, in the chapter on dinosaur paleoneurology, to see a cast of the inside of the casing of a T. rex brain, and to find the twelve cranial nerves, all lined up in order just like our own. And in the chapter on ankylosaurs, yet another casting of the inside of a braincase shows all twelve. Dinosaurs have what one author here calls "a high coefficient of weirdness," but I was amazed to learn from these examples that maybe they are not so distant after all.