When archaeological chemist Marvin Rowe recently scrambled up a narrow ledge in southeast Utah’s Black Dragon Canyon, he was determined to put an end—once and for all—to a lingering debate that has pitted rock art researchers and archaeologists against young-Earth creationists for decades. With his x-ray fluorescence gun in hand, he braced himself against the cliff face’s red rock and focused on the source of the conflict: a faded ancient rock painting soaring several yards above the dusty canyon floor. Some claim the image is that of a dragon or pterodactyl, but researchers have long maintained that it’s something far more mundane.

“It’s unfortunate that science has to keep fighting these battles,” says David Whitley in Tehachapi, California, one of the foremost experts on rock art in North America, who wasn’t involved in the study. “But because the painting continues to be used to promote nonscientific views of the world, it became necessary to demonstrate with complete clarity that those ideas are just wrong.”

The artwork was discovered by an amateur rock art enthusiast in 1928, but the roots of the quarrel can be traced to the late 1940s, when a man named John Simonson outlined what he thought was the edge of the pictograph in chalk, revealing a “winged monster.” (Once a common practice, chalking is now illegal because it can damage and obscure original images.) Three decades later, a geologist mused that the figure was similar to a pterosaur—a member of a group of flying reptiles that went extinct some 66 million years ago—and the stage for the controversy was set.

Because pterosaur fossils have been found in the area, young-Earth creationists, who believe our planet is between 6000 and 10,000 years old, began citing the painting in the late 1990s as proof that humans and the winged reptiles had inhabited the region together. In the past few years, some have even argued they can identify the species: Quetzalcoatlus northropi—the largest known pterosaur, with a wingspan of more than 10 meters.

Rock art researchers and archaeologists have disagreed strongly with that interpretation. In the mid-1990s, several scientists with eyes trained to recognize one of the region’s most famous styles of rock art—known as Barrier Canyon style—first argued that the so-called pterosaur was actually five figures: two humanlike ones and three animals, including what looks like a bighorn sheep and a horned serpent. Such pictographs are common in Barrier Canyon style, which is recognizable by the tiny “attendants”—which include people, birds, ungulates, and snakes, among others—nestled among the humanlike and often life-sized figures notable for their large eyes and elongated bodies.

Although the art is hard to date, researchers think pictographs (painted images, as opposed to petroglyphs, which are chipped or carved into rock) were created by artists from hunter-gatherer societies of the late Archaic Period (approximately 2000 to 4000 years ago) and perhaps blurring into the agrarian Fremont culture (approximately 1 C.E. to 1100 C.E.). Not a lot is known about the artists, but “the work is strongly indicative of the fact that the people who drew them were shamanistic in origin,” Whitley says.

Most examples of the striking imagery are in southeastern Utah. The largest numbers of sites are centered in and around a geological feature known as the San Rafael Swell and Canyonlands National Park, where the best-known example—the Great Gallery—is found.

Whitley first saw the Black Dragon Canyon panel 30 years ago. “It was obvious to any professional archaeologist that chalking an outline on the motifs, which is frankly a kind of vandalism, had completely misinterpreted the panel,” he says.

To the untrained eye, the image is perhaps a bit less clear. That’s partly because the painting has been exposed to the elements for at least a thousand years. Rain, when it does fall, has slowly leached some of the pictograph’s red ochre pigment, causing it to bleed and fade in places. And, as is often the case in such desert settings, a thin coating of calcium carbonate has also glazed the paint, further obscuring its exact edges.

Now, in a one-two punch, researchers have marshaled two modern techniques to analyze the ancient painting: a photographic enhancement program known as DStretch and a technique called x-ray fluorescence. The researchers first employed DStretch, a tool that can be used on computers and some cameras to boost and sharpen the original pigments of rock art, rendering colors that are sometimes invisible to the naked eye. Not satisfied yet, Rowe then used x-ray fluorescence to measure the iron content of the red ochre pigment, composed of iron oxide, to reveal exactly where there was (and wasn’t) paint on the sandstone rock.

“The advantage to both techniques is that they remove a great deal of the subjectivity of describing what you’re looking at,” says Rowe, a retired professor emeritus at Texas A&M University in College Station. The two methods revealed “pretty clearly” that the five figures that had been suggested previously, rather than a solitary pterosaur, graced the canyon wall, the researchers report this month in Antiquity. “It’s the final nail in the coffin for the pterosaur idea,” says Rowe, a co-author on the study.

One of the creationists referenced in the paper, Vance Nelson, wrote a book called Untold Secrets of Planet Earth: Dire Dragons, which argues that ancient people saw dinosaurs, which they called dragons, and depicted the creatures in art, including the Black Dragon Canyon pictograph. However, when he returned to the canyon and reexamined the pictograph shortly after his book was printed in 2011, he realized that the panel showed five separate images. He’s since removed the mention of the Black Dragon Canyon pterosaur from subsequent printings of the book, he says.

“I completely agree with their findings, and they did a good job,” Nelson says. “I’m disappointed they still referenced me in the paper because I don’t stand by that interpretation anymore.”

When he had his own revelation in 2011, he contacted others within the creation science community but was unable to change some minds, he says. “Hopefully this paper, which reveals details invisible to the human eye, will dissuade them from believing in the pterosaur.”

Still, Rowe says he has no illusions that most older creationists would be swayed at all by his arguments. “A young person with doubts, however, might start looking at the data.”