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Many of them resembled conical incisors, and in i856 this had caused a Latvian paleontologist to give them their name. Conodonts were in many formations but were most easily extracted from limestone and dolomite-the carbonate rocks. They would become useful to geologists because they flexplek huren leeuwarden were all over the earth, and because the creatures that left them behind had appeared in the world early in the Paleozoic and had vanished forever at the end of the Triassic. Yet not until the late nineteen-fifties did studies begin to be published that brought conodonts to prominence as index fossils, helping to subdivide a specific zone of time, a fifteenth of the history of the earth, running from 512 to 208 million years before the present. As the conodont-bearing creatures evolved through those years, their conodonts became increasingly complex, with apparatus extending in denticles, bars, and blades. Geologists, observing these changes, could readily assign relative ages to the places where conodonts were found. After collecting her samples, Anita could not have been shipping them back to a better place than Ohio State. Just as Johns Hopkins has been celebrated for lacrosse, Hartwick for soccer, and Rollins for tennis, Ohio State is known for conodonts. Geologists call Ohio State “a conodont factory.” Like all the other workers there (a specialist in the field is known in the profession as “a conodont worker”), she noticed incidentally as she catalogued the evolutionary changes in her specimens that some were light and some were dark. They were white, brown, yellow, tan, and gray. Since they were coming into Columbus from all over the United States, and in fact the flexplek huren rotterdam world, she began to notice that in a general way their colors followed geographical patterns. She wondered what that might suggest. She looked at conodonts from Kentucky and Ohio, which were of a yellow so pale it was almost white. From western Pennsylvania they were jonquil, from central Pennsylvania brown. The ones she had collected north of Schuylkill Gap were black.