Why People Believe Weird Things: Pseudoscience, Superstition, and Other Confusions of Our Time by Michael Shermer

not dig up thirty million fossil fragments. Rather, they extrapolated from selected exposed areas how many bones there were in the 1.25 by 0.25 mile bed. The hypothesizing began with a question: "What could such a deposit represent?" (p. 129). There was no evidence that predators had chewed the bones, yet many were broken in half, lengthwise. Further, the bones were all arranged from east to west—the long dimension of the bone deposit. Small bones had been separated from bigger bones, and there were no bones of baby Maiasaurs, just those of Maiasaurs between nine and twenty-three feet long. The find revealed more questions than answers. What would cause the bones to splinter lengthwise? Why would the small bones be separated from the big bones? Was this one giant herd, all killed at the same time, or was it a dying ground over many years?
    An early hypothesis that a mudflow buried the herd alive was rejected as "it didn't make sense that even the most powerful flow of mud could break bones lengthwise ... nor did it make sense that a herd of living animals buried in mud would end up with all their skeletons disarticulated." Applying the hypothetico-deductive method, Horner formulated a second hypothesis: "It seemed that there had to be a twofold event, the dinosaurs dying in one incident and the bones being swept away in another." Since there was a layer of volcanic ash a foot and a half above the bone bed, volcanic activity was implicated in the death of the herd. Deduction: because the fossil bones split only lengthwise, the damage to the bones came long after the event that caused death, which might have been a volcanic eruption, especially since volcanoes "were a dime a dozen in the Rockies back in the late Cretaceous." Conclusion: "A herd of Maiasaura were killed by the gases, smoke and ash of a volcanic eruption. And if a huge eruption killed them all at once, then it might have also killed everything else around," including scavengers or predators. Then perhaps there was a flood, maybe from a breached lake, that carried the rotting bodies downstream, separated the big bones from the small bones (which are lighter), and gave them a uniform orientation. "Finally the ash, being light, would have risen to the top in this slurry, as it settled, just as the bones sank to the bottom." What about the baby Maiasaurs? "Perhaps the babies of that year were still in the egg or in nests when the volcano erupted, or perhaps nesting had not even begun." But what about babies from the previous season who would now be juveniles? Horner admits "that nobody knows for sure that these dinosaurs would have produced young each year" (pp. 129-133).
    Even in the first stage of a dig while fossils are being released from their rocky shroud, the hypothetico-deductive method is constantly applied. When I arrived at Horner's camp, I expected to find the busy director of a fully sponsored dig barking out orders to his staff. I was surprised to come upon a patient historical scientist sitting cross-legged before a cervical vertebra from a 140-million-year-old Apatosaurus and wondering just what to make of it. Soon a reporter from a local paper arrived (apparently a common occurrence as no one took notice) and inquired of Horner what this discovery meant for the history of dinosaurs. Did it change any of his theories? Where was the head? Was there more than one body at this site? And so on. Horner's answers were consistent with those of the cautious scientist: "I don't know yet." "Beats me." "We need more evidence." "We'll have to wait and see."
    This was historical science at its best. For example, after two long days of exposing nothing but solid rock and my own ineptness at seeing bone within stone, one of the preparators pointed out that the rock I was about to toss was a piece of bone that appeared to be part of a rib. if it was a rib, then the bone should retain its rib-like shape as more of the overburden was chipped away. This it did for