Upper Ordovician Chitinozoans from the British Historical Type Areas and Adjacent Key Sections

ABSTRACT Recent developments in chronostratigraphical procedure and new biostratigraphical insights have necessitated revision of the Ordovician System's chronostratigraphy. As a part of this process, the chitinozoan assemblages from the historical type areas of the British Caradoc and Ashgill Series are described, and the first Upper Ordovician chitinozoan biozonation for British Avalonia is established. The historical Caradoc and Ashgill type sections in the Anglo-Welsh basin yield important chitinozoan assemblages; these data are supplemented with information from other British key sections with accurate graptolite control. As a result, the established chitinozoan biozonation for British Avalonia is tied closely to the British chronostratigraphical framework and graptolite biostratigraphy. This volume provides systematic descriptions of the chitinozoan taxa recovered from the sections studied during this biozonation project in the UK, comprising 23 genera and 131 species, of which five are new: Acanthochitina latebrosa, Acanthochitina pudica, Belonechitina brittanica, Hercochitina frangiata and Spinachitina katherinae.