Chitinozoan zonation of the Late Ordovician and the Early Silurian of the Island of Anticosti, Quebec, Canada

A reappraisal of chitinozoan distribution across the Ordovician-Silurian bo undary on the Island of Anticosti has led to the recognition of a new zone, the Ancyrochitina ellisbayensis biozone, in the uppermost part of the Elli s Bay Formation. This biozone lies between the well defined Upper Ordovicia n Spinachitina taugourdeaui biozone and the lowest Silurian (Rhuddanian) Pl ectochitina nodifera biozone of the Becscie Formation. The occurrence of su ch diagnostic species as P. nodifera, Belonechitina postrobusta, Conochitin a electa and Ancyrochitina ramosaspina in the Lower Silurian of Anticosti p oints to a close similarity to faunas in Estonia and north Latvia and indic ates an age ranging from the Parakidograptus acuminatus to the Coronograptu s cyphus in terms of graptolite zones. The chitinozoan biozonation harmoniz es with that based on conodonts and, to a lesser extent, with the known gra ptolite faunal succession. Five new species: Ancyrochitina ellisbayensis sp . nov., Clathrochitina postconcinna sp. nov., Conochitina gunriveris sp. no v., Clathrochitina perexilis sp. nov., Bursachitina basiconcava sp. nov, an d three species in open nomenclature are described. (C) 2000 Elsevier Scien ce B.V. All rights reserved.