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Evolutionary biologists have found fossil evidence of 110 species of pterosaurs, with wing spans ranging from 10 inches to over 33 feet

I scout potential sites for camping and photography trips by looking at maps and reading about landscapes and habitats, so I was optimistic that I had found an outstanding site when I saw Black Dragon Canyon on the sharp rise of the San Rafael Swell. This site had not only a narrow and deep canyon, but also a panel of Native American rock art called the Black Dragon Pictograph. This sounded intriguing to me, for I was unaware that Native Americans included dragons in their legends, tales or rock art.Ìý

Black Dragon Canyon is 16 miles west of Green River, on the abrupt and jagged rise of the San Rafael Reef. From the parking area, a trail winds about a mile through the Canyon to the pictograph site. Ìý

When I found the pictograph, I have to admit that I was both disappointed and puzzled. Someone had outlined the pictograph in white chalk and that vandalism detracted immensely from the experience of viewing an authentic, ancient pictograph. But in addition, I could see that the chalk outlined pigmented areas, but to my eye it seemed that the chalk also included areas that had not been colored. The head of the "dragon" was apparent, but in its entirety it was not a convincing depiction of a dragon.Ìý

In 1947, John Simonson published a paper describing his application of chalk to clarify the size and shape of what he perceived to be a large, winged monster. Several decades later a geologist expressed his impression that the pictograph resembled a pterodactyl. In the late 1990s young-earth creationists, who believe that earth is between 6,000 and 10,000 years old, started using the black dragon pictograph as evidence that pterodactyls and Native Americans lived at the same time.

Evolutionary biologists have found fossil evidence of 110 species of pterosaurs, with wing spans ranging from 10 inches to over 33 feet. Pterosaurs, including pterodactyls, persisted for 150 million years but none of the species survived the meteor strike that triggered the extinction of all the large dinosaurs 65 million years ago. Genetic data enabled evolutionary biologists to estimate that the first fully modern humans lived in southern Africa 200,000 years ago.Ìý

When experts in the Barrier Canyon style of pictographs and petroglyphs looked at the panel, they saw five separate figures, not one dragon. Convinced the pterodactyl interpretation of the pictograph was incorrect, archeologists studying rock art used two techniques to critically examine the Black Dragon Panel and to put the controversy to rest.

The first technique was Dstretch, a digital imaging tool designed to enhance photographs of pictographs. It is capable of revealing the presence of pigments faded to the point that they are no longer visible to the human eye. The second technique was x-ray fluorescence, which measures the iron concentration in the red pigment, to clearly discern exactly where Native Americans applied pigment on rock surfaces. Each of these techniques produces results independent of the preconceived notions of the user.Ìý

Dstretch and x-ray fluorescence were in agreement in their resolution of the Black Dragon Panel into five separate pictographs. On the left are two small figures, a bighorn sheep and a dog. Next is a large, bug-eyed anthropomorph with a snake in its hand. Further to the right is the figure of a man, bent at the waist with arms outstretched in supplication. The last figure to the right is a large, sinuous horned snake. All five figures are characteristic of the Barrier Canyon Style, which was used from 4,000 to 1,500 years ago, and was named for a series of rock art panels along Barrier Creek, just 45 miles away.Ìý

In the 1940s, Simonson misinterpreted a pictograph that had become faded from thousands of years of sunlight, rain and accumulation of salt scale. Then he chalked the outline of what he thought he saw. His imagination turned the figure of a supplicating man into the neck, head and beak of a monster. In the 1970s the chalk outline suggested a pterodactyl to an innocent geologist and in the late 1990s that suggestion was embraced uncritically by young-earth creationists motivated by a religious agenda. Ìý

It would be grand if Native Americans saw pterodactyls with wingspans exceeding 33 feet soaring in the sky, but it never happened. All of the pterodactyls were gone 65 million years before the first modern humans arose.

Applying chalk to pictographs was never a good idea and today modification of rock art in any way it is explicitly illegal, punishable with both fines and jail time.