Extreme makeover

Rudolph Zallinger ’42BFA, ’71MFA

The Age of Reptiles mural in the Peabody Museum spans 110 feet and nearly 300 million years. We asked an artist to show what a version of the leftmost sections—the Jurassic and Cretaceous periods—might look like if painted with today's knowledge of dinosaurs. (See next page.) View full image

When the current headquarters of the Peabody Museum of Natural History opened in 1925, its hangar-sized Great Hall, then as now, was the centerpiece of its exhibits—filled with the likes of Stegosaurus, Triceratops, and other massive fossils unearthed by Othniel Charles Marsh, Yale's first paleontology professor and a celebrated nineteenth-century bone hunter. Nevertheless, in the early 1940s, Peabody director Albert Parr found the room wanting. Its walls were too gray and drab. Perhaps, he said, they could be "spruced up."

Parr had already hired a Yale School of Fine Arts student, Rudolph Zallinger ’42BFA, ’71MFA, to produce some illustrations of seaweed. Might Zallinger be interested in a slightly larger challenge? Parr's idea was to bring the fossils to life with a series of dinosaur paintings on panels on the east wall. But Zallinger was more ambitious. He proposed a "panorama of time": a mural 110 feet long and 16 feet tall, telling the complete story of dinosaur evolution, from the emergence of the dinosaurs' ancestors in Devonian swamps 362 million years ago to the demise of the "ruling reptiles," 65 million years ago at the end of the Cretaceous Period.

Zallinger started the project in 1942 and completed it on June 6, 1947. As spruce-ups go, The Age of Reptiles was a colossal success. It was featured on the cover of Life magazine in 1953, as well as on a U.S. postage stamp in 1970. For young scientists of the time, it was inspiring, says Yale paleobotanist Leo Hickey: "This room has been called the Sistine Chapel of evolution."

Scientifically, says Yale paleontologist and geology professor Jacques Gauthier, "the Zallinger mural was the leading-edge production of its time." Zallinger had gotten a crash course in dinosaur science from some of the best researchers at Yale and Harvard, and his mentors constantly checked in to make sure his representation was as accurate as possible.

But current science has turned The Age of Reptiles into its own kind of dinosaur. In the 1940s, the prevailing view of dinosaurs "was that they were a bunch of big, slow-moving, stupid, cold-blooded clunkers," says Gauthier. And no one subscribes to that notion anymore, says Jack Horner, Regents Professor of Paleontology at Montana State University-Bozeman (and the inspiration for Alan Grant, the lead character in Jurassic Park). There's been a revolution in our way of thinking about dinosaurs, and much of it, according to Horner, can be traced back to one man—John Ostrom, who joined the Yale faculty in 1961. "John rebuilt our image of dinosaurs," Horner says.

In 1964, on the last day of a prospecting trip in the Montana badlands, Ostrom and his field assistant, Grant Meyer, found one of the most important fossils in the history of paleontology. They noticed some large, sharp claws protruding from a hillside, and they "both nearly rolled down the slope in our rush to the spot," Ostrom later recalled. "It was evident . . . that we had stumbled across something very unusual and quite unlike any previously reported dinosaur."

Ostrom named the find Deinonychus antirrhopus—"counterbalancing terrible claw"—after the lethal, sickle-shaped claw on each of the animal's feet, clearly used to slash or stab prey. This ten-foot-long predator, he proposed, was no slow-moving clunker but a lithe, athletic, intelligent hunter. Thus began the revolution.

Ostrom even suggested that Deinonychus was warm-blooded. It was a heretical concept that had been out of favor for a century. "John's speculations were greeted with shrieks of horror by the traditionalists," says Robert Bakker ’67, who worked with Ostrom as a field assistant and would later champion the idea of warm-bloodedness. (Bakker traces his interest in paleontology to Zallinger's mural.)

The discovery of Deinonychus helped set off a flurry of new work on dinosaurs. Today the jury is still out on the question of their metabolism, but another of Ostrom's heresies has become gospel. (Ostrom died in 2005.) In the early 1970s, he analyzed the skeleton of Archaeopteryx, the first bird, and found so many similarities between it and Deinonychus that in 1973 he suggested they were close relatives.

He went further (and resurrected another long-derided theory) by concluding that Deinonychus and many of its cousins, including Tyrannosaurus rex, had had feathers. His deduction was verified in the 1990s when researchers digging in northeastern China discovered a trove of exquisitely preserved, 120-million-year-old feathered dinosaurs. For most paleontologists, the Liaoning fossils clinched the argument that today's birds are descended from dinosaurs.

Ostrom's discoveries and insights, says Jacques Gauthier, "started a genuine dinosaur renaissance." Today, dinosaur researchers have found evidence for a plethora of behaviors and abilities that were once thought to be exclusively the province of birds and mammals.

Many dinosaurs, Deinonychus included, laid eggs and brooded them in nests. Some dinosaurs protected their young; many species traveled, no doubt for safety and mutual interest, in herds made up of individuals of all sizes and ages. Hadrosaurs (or duck-billed dinosaurs), such as Parasaurolophus walkeri, may have communicated with their herds by forcing air through the hollow pipelike structures on their heads. Males of some species, like Pachycephalosaurus, probably fought each other for access to females.

Below, Yale paleontologists Leo Hickey, Jacques Gauthier, and Daniel Brinkman provide a guided tour of The Age of Reptiles, showing where the prevailing wisdom of the day sent the painter down the wrong path. The Yale Alumni Magazine commissioned dinosaur artist Alan Male to update a section of the mural—from about the time depicted in Jurassic Park to that split second, 65 million years ago, just before a huge meteor slammed into the Earth and helped send T. rex and its Cretaceous relatives into extinction.

The Peabody intends to update The Age of Reptiles—but only virtually—as part of a twenty-first-century sprucing up. The mural will not be painted over; instead, the museum will install interactive touchscreens and multimedia displays in the Great Hall, where visitors will be able to study up-to-date illustrations and read about current dinosaur science. It's a certainty that new research will necessitate frequent revisions.