Deducing the Physiology of Mesozoic Giants

The topic for review in this edition is a recent book with the strange title of Dinosaurs, Spitfires, & Sea Dragons by Christopher McGowan, Harvard University Press, 1991. The hard back version goes for $29.95 and should be available for you purists through special order at better book stores; the soft cover edition is at book stores now at $14.95.

The author is Curator of Vertebrate Paleontology at the Royal Ontario Museum and Professor of Zoology at the University of Toronto. As is the case with most paleontologists, the author has a specialty. His is the ichthyosaurs which is evident by the amount of material devoted to this subject.

The premise of the book is to logically deduce the physiology of the Mesozoic giants of the land, sea, and air. Since we are 65 million years too late to see locomotion, soft part anatomy, or habits, the author uses facts we know about modern animals to infer how these extinct animals functioned.

The book is technically oriented but not to the point of being filled with highly specialized jargon. Any time complex terminology is used it is always well defined in simple terms.

The first chapter of the book is devoted to a discussion of mechanical engineering as it relates to strength of materials, stress, and strain. Never fear, as I stated above, all is well explained and easy to understand; you don't have to be an engineer to comprehend what is said. This chapter lays the foundation for subsequent chapters on "How the Vertebrate Skeleton Works" and "Reading a Dinosaur Skeleton". Later chapters provide similar treatment to principals of fluid dynamics prior to discussions of the mechanics of swimming and flying.

The "engineering" principles are used in each chapter to analyze and understand the workings of these once living creatures. For example, the blood pressure of a modern giraffe is used to discuss the possibility of brachiosaurs having an auxiliary heart or whether they carried their head and neck parallel to the ground. Did you know that giraffes splay their front legs when drinking to prevent their heart from being too much higher than their head? This technique minimizes the change in blood pressure to the brain and prevents the animal from fainting when raising his head back up.

Warm bloodedness is discussed in the chapter "What's Hot and What's Not". You may be surprised to find that there is a continuous variation between "hot bloodedness" and "cold bloodedness"; it's not just a black and white distinction. McGowan diplomatically takes exception to some of Robert Bakker's statements without actually naming him. Did you know that some modern fish are partially "warm blooded"? Tunas maintain a body temperature about ten degrees Celsius higher than the water temperature; and swordfish maintain their brain and eyes at an elevated temperature.

The chapter concerning flight, "The Winged Phantom", discusses flight dynamics and whether pterosaurs could maintain flapping flight or were soarers or gliders. McGowan also discusses the problem of walking; could pterosaurs walk on their hind legs only or did they need their arms (wings) as well? These questions are tackled through analysis of hip and upper leg bone shape.

The book concludes with the obligatory chapter on extinction. All of the latest theories are presented along with the author's interpretations.

I highly recommend this book despite the odd title. It is not difficult to read and gives one an understanding of how paleontologists draw conclusions from the fossils. It also provides another example of the need to understand living animals of all types in order to help understand the animals of the past.

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