Killers Remain at Large

A young art school graduate named Rudy Zallinger took a stick of charcoal in hand and stared apprehensively at the expanse of white wall in the Great Hall of the Peabody Museum of Natural History at Yale University. Three and a half years later, in June 1947, he completed "The Age of Reptiles" mural, the most vivid ecological portrayal of life in the Mesozoic Era of its time.

In Zallinger's rendering, the ubiquitous swamps and lowlands of the Triassic and Jurassic periods gave way to erupting volcanoes and drier forests in the Cretaceous. Flowering plants, including magnolias, added a modern familiarity (according to more recent interpretations, however, these were included prematurely).

Although the American bone wars were long over, zealous excavation abroad unearthed dinosaurs on every continent except Antarctica. Continental drift was still a crazy fantasy, so land bridges between modern continents were used to explain global dinosaur distribution. The fact that dinosaurs really did rule the world until the end of the Cretaceous Period provoked wide and almost completely unsubstantiated speculation about their extinction.

As late as the 1950s, Roy Chapman Andrews still promoted a pet idea that his boss at the American Museum of Natural History, Henry Fairfield Osborn, had championed a generation earlier. Along with Teddy Roosevelt and other promoters of the "strenuous life" of rugged, manly pursuits for sissified city boys, Osborn was ultimately worried about protecting the racial vitality of white upper-class humans. Reading this moral into the fossil record, Osborn saw "racial senescence" as the decline of a species when overspecialization left animals unable to adapt to new conditions. So, the theory went, the flamboyant head frills of the Late Cretaceous Triceratops and its cousins spelled degeneration and doom (rather than being a natural result of developing powerful chewing muscles).