The Great Fossil Enigma: The Search for the Conodont Animal (Life of the Past)
Simon J. Knell
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Stephen Jay Gould borrowed from Winston Churchill when he described the conodont animal as a "riddle wrapped in a mystery inside an enigma." This animal confounded science for more than a century. Some thought it a slug, others a fish, a worm, a plant, even a primitive ancestor of ourselves. The list of possibilities grew and yet an answer to the riddle never seemed any nearer. Would the animal that left behind these miniscule fossils known as conodonts ever be identified? Three times the animal was "found," but each was quite a different animal. Were any of them really the one? Simon J. Knell takes the reader on a journey through 150 years of scientific thinking, imagining, and arguing. Slowly the animal begins to reveal traces of itself: its lifestyle, its remarkable evolution, its witnessing of great catastrophes, its movements over the surface of the planet, and finally its anatomy. Today the conodont animal remains perhaps the most disputed creature in the zoological world.
also felt the protoconodonts an irrelevance. He thought they were more likely Szaniawski's chaetognaths than conodont ancestors. He preferred to see the conodonts as a unique group that emerged from that great evolutionary experiment recorded in the Burgess Shale: “More than a century of trying to make conodonts something else has done little more than emphasize their uniqueness…. So a reasonable reply to the query ‘What are conodonts?’ ought to be ‘They are conodonts,’ oughtn't it?”8 He had told
from the New Albany shale of Indiana,” Bull. Am. Paleont. 21 (1934). 29. C. L. Cooper, “Conodonts from the Upper and Middle Arkansas Novaculite, Mississippian, at Caddo Gap, Arkansas,” J. Paleont. 9 (1935): 307–15. 30. E. B. Branson and M. G. Mehl, “The conodont genus Icriodus and its stratigraphic distribution,” J. Paleont. 12 (1938): 156–66. 31. M. M. Knechtel and W. H. Hass, “Kinderhook conodonts from Little Rocky Mountains, northern Montana,” J. Paleont. 12 (1938): 518–20, 520; E. B.
looking: “The first job of conodonts was to demonstrate the value of “nuts and bolts” in stratigraphy. This is being done and on a larger scale than many paleontologists would have guessed. A complete reliable and world-wide zonation of Middle Cambrian to Upper Triassic strata based on conodonts may be possible.” But this Treatise would suffer the fate of the first one: Delayed in publication, it too would be out of date by the time it finally appeared in 1981. The revolution that had taken
Nicoll's fused conodont clusters. In one pair the left element overlaps the right; in the other the reverse is true. Reproduced with permission from C. B. Rexroad and R. S. Nicoll, Journal of Paleontology 26 (1964). SEPM (Society for Sedimentary Geology). In the summer of 1961, Bergström and Sweet had made a “grand traverse of the Ordovician exposures of the eastern Midcontinent.” This gave them a panoramic outlook that would affect their work together over the coming decade. With Sweet's
perhaps hundreds or thousands of meters of rock. As the conodonts showed a color range much like that seen in butter heated in a pan, she imagined that the color of the fossils might be used as an indicator of the maximum temperature experienced by the rocks in which they were found, as temperatures underground increase with depth. However, finding no encouragement at the Survey, she quickly dropped the idea. It was a chance meeting and conversation with Leonard Harris (later to be her second