Review: June 2016

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We learn about living things by observing whole individuals in the wild or in captivity, but extinct creatures are only known through the fragments they leave behind. So it’s no wonder that Tyrannosaurus, a dinosaur of iconic status these days, once went by several other names— Deinodon, Manospondylus, and Dynamosaurus, among others—before paleontologists were able to conclude that the disparate body parts they were extracting from various sites all belonged to the same vanished genus.

It was Barnum Brown, of the American Museum of Natural History in New York, who suggested the name Tyrannosaurus for the giant carnivore. He brought back a largely complete specimen from Alberta in 1906, giving the public, for the first time, an idea of what the whole fearsome creature looked like. It is still on display, inspiring generations. Bones, eggs, tracks, and coprolites (fossilized droppings) of Tyrannosaurus collected over the succeeding century have begun to supply paleontologists with a coherent picture of its anatomy, physiology, and behavior. “Quite simply,” writes David Hone of Queen Mary University of London, “we know more about Tyrannosaurus than any other extinct dinosaur and as a result its biology is a superb topic for discussion.”

Accordingly, Hone has written a lively but detailed natural history for Tyrannosaurus along the lines of what an academic zoologist might write about aye-ayes, tree frogs, or honey badgers—except that these giants have been extinct for 65 million years. Here you will find a family tree of the roughly twenty-five known Tyrannosaur species, tracing bloodlines from the first appearance of the species Proceratosaurus around 167 million years ago, to the great extinction at the end of the Cretaceous period, a remarkable 100 million years later. During this period, Tyrannosaurs showed not only impressive staying power, but also astonishing growth in size—the earliest species measured under fifteen feet in length; the later species were upward of twice that.

If most of what you know about Tyrannosaurs is based on old Japanese movies or the Jurassic Park franchise, there will be many surprises. You’ll learn that, although the big beasts may have had scales on some parts of their bodies, feathers were probably present, as befits the ancestors of modern birds. They walked erect, not crouched over in a threatening pose, but nonetheless could move rapidly to chase prey. Once they caught that prey, however, they had a problem: the later species’ arms were tiny, with only two fingers on each hand. Smaller animals could have been dispatched in a single bite, but it seems that larger prey were stopped cold by strategic chomps to the most exposed part of a fleeing animal: the tail. Indeed, two fossil hadrosaurs have been found with tyrannosaur bites in their derrieres.

Many gaps in the picture remain, of course. Fossil skeletons are invariably incomplete, and for many of the species described here, only a single individual or a few bones have so far been recovered. Fossilized evidence of behavior—preserved tracks, bite marks, and the like—are even harder to come by. So though The Tyrannosaur Chronicles is a welcome touchstone volume for lovers of the terrible lizards, further discoveries and surprises are doubtless in store.