But where the strange, seedy human world of the dinosaur artist is richly realized, less so is the alien world of the dinosaur at the center of the story itself. There is no introduction to the lost world these monsters stalked, what Mongolia was like 70 million years ago, or how a creature as preposterous as T. bataar ever came to exist on our planet. Besides a few unavoidable references to the creature’s specifications and bite strength, for the most part the dinosaur at the center of the story serves the role of MacGuffin.

That’s because at heart, this is not a book about dinosaurs, it’s a book about people; a true-crime book, and a thoroughly reported one at that. It is peppered with useful précis on towering figures from natural history — we join the 19th-century naturalist and savant Mary Anning, for instance, plying the Jurassic Coast for ichthyosaurs, and stand with the father of Deep Time himself, James Hutton, as he stares down the abyss of time represented in an outcrop in Scotland, contemplating the successive layers of earth that created it. But such potted histories are eddies in the narrative stream that carries Eric Prokopi from taciturn Florida high school swim star to eventual bone smuggler and felon.

In the end Prokopi, like T. bataar, remains something of a cipher in spite of Williams’s nanoscale examination of him, his family, friends, associates, finances, even home décor. Sometimes this intimacy borders on overexposure, though it also produces some arresting vignettes: One of the most effective passages meticulously recounts Prokopi’s drive to prison in order to surrender — a trip rendered both comically mundane and dreadful. But Prokopi himself, who doesn’t say much and seems constitutionally incapable of showing his cards, remains elusive.

Instead, the book’s most memorable character may be Mongolia itself, a rugged physical and political terrain that defies easy generalization or the exoticizing accounts of Westerners. We pick up the thread with the mind-blowing global conquests of Genghis Khan and follow it through to the early 20th century, and the accounts of the American naturalist and inveterate self-promoter Roy Chapman Andrews, who briefly descended on Mongolia on behalf of the American Museum of Natural History, forging there a romantic persona as a man committed to digging up dinosaurs. Andrews’s life is almost too colorful to recount, and the contributions he made to popular interest in paleontology were real and lasting. But as with many sepia-toned institutional heroes, the luster of his accomplishments has dimmed in retrospect, not least because he minimized the contributions of his Mongolian assistants in service of a queasy American imperialism. In 1932, the Natural History Museum pulled out of the country as Mongolia descended into Stalinist Communism, executing 30,000 intellectuals and Buddhist leaders, eradicating traditional garb, Mongolian vertical script and Khan as a symbol of national pride — all bourgeois indulgences.

Sixty years later, when Communism fell, the country was once more flooded with opportunistic Americans, many of them hatched in right-wing American think tanks. It was in the wake of this post-Soviet moment of free-market national ransacking that Prokopi found an opening to extract the country’s dinosaur heritage. But just as Khan was suddenly loosed from his symbolic exile and restored as a totem of national pride when Communism fell, when Prokopi falls, hope for a future of Mongolian self-determination comes in the form of a far more ancient, even fiercer symbol of restored national pride: T. bataar.