Tumulduria incomperta and the case for Tommotian trilobites |
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Authors: | STEFAN BENGTSON ALEKSANDR B FEDOROV VLADIMIR V MISSARZHEVSKY ALEKSEI Yu ROZANOV ELENA A ZHEGALLO REY Yu ZHURAVLEV |
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Institution: | Institute of Palaeontology, Box 558, S-751 22 Uppsala, Sweden;SNIIGGiMS, Krasnyj prospekt 67, SSSR-630104 Novosibirsk, USSR;Geological Institute, USSR Academy of Sciences, Pyzhevskijpereulok 7, SSSR-109017 Moscow, USSR;Palaeontological Institute, USSR Academy of Sciences, Profsoyuznaya ulitsa 123, SSSR-117868, GSP-7, Moscow, V-321, USSR |
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Abstract: | The enigmatic fossil Tumulduria incomperta Missanhevsky 1969 from the basal Tommotian Stage at 'Dvortsy' on the Aldan River, Siberian Platform, is reinvestigated in light of the report (Fedorov et al. 1979, Dokl. AN SSSR 249) of trilobite remains from the same beds. Comparisons of these supposed trilobites with old and new collections from 'Dvortsy' leave no doubt that they are identical to Tumulduria incomperta. Tumulduria is represented by phosphatic plates with a crude bilateral symmetry, consisting of a central longitudinal rounded ridge flanked by flat lateral portions. They are built of growth lamellae overlapping each other along the axis of symmetry. The surface carries prominent transverse folds and lamellar terminations. There is considerable morphological variation, and the similarity of some specimens to trilobites is only superficial. Tumulduria is interpreted as a bilaterally symmetrical metazoan with a dorsal protective plate; it probably represents a short-lived group that left no descendants. |
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Keywords: | Problematica Trilobita Tumulduria morphology taxonomy biostratigraphy Siberian Platform Tommotian Stage Lower Cambrian |
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