POLYMERID TRILOBITES OF THE MANUELS RIVER FORMATION, NEWFOUNDLAND, CANADA

Trilobites are among the best studied and most important index fossils of the middle Cambrian. With this contribution we show preliminary results of the systematic revision of the polymerid trilobite fauna from the type locality of the Drumian (middle Cambrian, Series 3) Manuels River Formation, Conception Bay South, Newfoundland, Canada. The fossil-rich grey to black shales with minor interbedded calcareous concretions were deposited on the former microcontinent Avalonia and show features of a typical condensed succession. In part the fossils show pyritization due to the oxygen depleted environment and diagenetic impact. The containing fauna consists of trilobites, brachiopods, hyoliths and acritarchs.

Previous studies were mainly taken several decades ago and focused on different aspects. The original description of the stratigraphy and trilobite fauna at the type locality of the Manuels River Formation was done by Howell in 1925. In 1962, Hutchinson revised and refined the Cambrian lithostratigraphy and trilobite systematics in southeastern Newfoundland, which included the trilobite fauna in Conception Bay South. The herein studied well-preserved specimens are part of a new collection, sampled bed by bed from the c. 20 m thick succession, consisting mainly of articulate cephali, several pygidia, and broken segments. The polymerid trilobites are mainly assigned to the Order Ptychopariida.