| Abstract: | An Upper Ordovician chitinozoan biozonation for British Avalonia is established. The new scheme is based on chitinozoan faunas from the historical Caradoc- and Ashgill-type sections in the Anglo-Welsh area; these data are supplemented with information from other key British sections that have accurate graptolite control. As a result, the chitinozoan biozonation for British Avalonia is tied to both the British chronostratigraphical framework and the graptolite biostratigraphy. It consists of 13 chitinozoan bio(sub)zones and for the first time provides a formal chitinozoan biozonal scheme for the Upper Ordovician of Britain, which can be tied with the well-established biozonation in Baltoscandia. This predominantly Baltoscandic signature of the new British chitinozoan biozonation is consistent with Avalonia's northwards migrating palaeogeographical position during the Ordovician. |
