The Giant Trilobites of Newfoundland

The first edition of my atlas contained a firsthand description of my encounter with the Middle Cambrian Paradoxides beds of Eastern Newfoundland. This field trip was singled out as deserving a special mention in my book, as it represented a significant episode of scientific discovery. It also told an exciting story linking together Carl von Linne's first identified trilobite, Entomolithus paradoxus, the Newfoundland trilobites that I dug out, and spectacular evidence of continental drift. The excitement has not abated in the intervening years. In fact, a systematic study of the strata holding the giant Paradoxides of Newfoundland (Bergstrom and Levi-Setti 1978) has revealed a fascinating sequence of evolutionary events. This time, I felt compelled to present, as a case history, the completion of a story that left a lingering degree of frustrated suspense in Appendix A of my first edition.

The story began on a very wet and cold afternoon in the summer of 1974, when I dug out my first giant Paradoxides from the shale beds exposed in the gorge of the Manuels River, on the coast of Conception Bay, in Eastern Newfoundland. The lore of the paleontological discoveries of the last century flashed briefly through my mind. It was uncanny to me that all of a sudden I could hold in my hand such a treasure, only known to me from the sepia lithographs found in the monographs of the last century's masters, describing the trilobites of Bohemia, Sweden, and Wales. I was aware, from the ongoing work at the University of Chicago by A. M. Ziegler and C. R. Scotese (see Scotese and McKerrow 1990, for a recent review), that Maritime North America, including the Avalon Peninsula, South Wales, and Spain were thought to be part of a sequence of land masses facing North Africa in Gondwana (see figure 18), prior to the crunch of Pangea. These would become reassembled as part of Europe and North America in the subsequent drift that created the present Atlantic Ocean. Somehow, a bite of the old world had been carried along by the North

American continent, when it split away from Eurasia. The layers I was digging into were deposited during the Middle Cambrian. They are resting on Lower Cambrian sediments and Precambrian rocks, and are in turn buried under Upper Cambrian and Ordovician strata. This entire sequence was transported with minimal disturbance, so that the fossils that these strata contain have retained their original morphology and are beautifully preserved. The same marine animals that were buried and fossilized along several shorelines of a fragmented proto-Europe can thus be found in rocks of the same age on both sides of the Atlantic. All this I had read about. But now I was holding this fantastic trilobite, bright yellow and red, even more so under the rain, that was once buried in a very distant and very old Europe. I could touch the amazing reality of continental drift.

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