"Until now that claim has gone unchallenged."
So write Phil Senter and Sally J. Cole, coauthors of a newly published paper in Palaeontologia Electronica examining the purported dinosaur petroglyphs of Kachina Bridge, a rock formation in Utah's Natural Bridges National Monument. While folks have criticized the attempts of Young Earth Creationists to use these and other ancient markings of indigenous people as evidence of humanity's coexistence with dinosaurs - visit Stupid Dinosaur Lies to see a comparison of different images they've used in this particular case - it's now been addressed in the scientific literature. Analyzing the markings under a variety of lighting conditions, Senter and Cole were able to discern that what seemed to be superficially resemble a generic sauropod was actually an amalgam of deliberate ancient markings and natural variations in color on the rock.
From Senter and Cole's "Dinosaur" petroglyphs at Kachina Bridge site, Natural Bridges National Monument, southeastern Utah: not dinosaurs after all.
In their discussion section, Senter and Cole write of pareidolia, "the psychological phenomenon of perceiving significance in vague or random stimuli, e.g., seeing animals in clouds or the face of a religious figure in a food item. The results of this investigation indicate that the dinosaurs of Kachina Bridge are examples of this phenomenon and exist only as pareidolic illusions." This is one of the great perceptual hurdles we must leap in our attempt to accurately perceive our world. It happens to all of us. It's happened to me. In the latest episode of Point of Inquiry, Neil DeGrasse Tyson makes the point that science is essentially a tool to protect our observations from the biases and failings of our brains. One of these failings is our zeal for pattern-recognizing. Drop the Mentos candy of pareidolia into the Diet Coke of ideology and stand back.
While this study could be seen as just a bit of housecleaning to dispense with yet another creationist claim, it perfectly illustrates the power of science to allow us to observe that which fools the eye. It demonstrates that science is about the willingness to admit our physical limitations, to go beyond the superficial and rigorously analyze that which seems obvious. Creationists don't do this. They don't attempt to test and strengthen their arguments by poking holes in them. Any creationist proclaiming Kachina Bridge as evidence for a young Earth could have done exactly what Senter and Cole did; their methods were not beyond the capabilities of anyone with the time and will to try. But none did, because the truth of the claim wasn't their concern. And that says everything.
It also must be said that if you look at the alleged sauropod, it doesn't quite match our understanding of the real animals' physiology. If the Kachina Bridge petroglyph was the work of an ancient artist who had actually had seen a sauropod, it would have sported a horribly broken tail. On a more basic level, I'd imagine that had any early artists actually shared their environments with dinosaurs, their depictions in petroglyphs would be so widespread that the creationists would have no trouble finding abundant evidence for their claims. Bison and aurochs and horses are really cool animals, but if I was a guy in a cave with a bit of ochre paint, I'd personally be more interested in populating the stone walls with the titanic saurian beasts that dwarfed them. Then again, who am I to make assumptions about the priorities of ancient artists?