A shark fauna from the Campanian of Hornby Island, British Columbia, Canada: an insight into the diversity of Cretaceous deep-water assemblages

Abstract

ABSTRACT This article describes a rich and diversified elasmobranch fauna collected from the Upper Campanian Northumberland Formation, a part of the Nanaimo Group, exposed on Hornby Island, British Columbia, Canada. This fauna consists of 30 species belonging to 26 genera and is characterised by a large number of new elasmobranch taxa (17 species, 7 genera and 2 families); all these principally belong to the usual deep-water squalomorphs (e.g. Chlamydoselachiformes, Hexanchiformes, Echinorhiniformes, Squaliformes, Pristiophoriformes). This elasmobranch association displays two striking features: no batoid taxa have been found despite the extremely fine process of collection, and it is mainly composed of taxa living in a deep-water environment. The identified species have a large panel of body size estimated between about 50 cm (Eoetmopterus?) up to probably 3 to 4 metres long (eg. Xampylodon nov. gen., Carcharias) and maybe more for Dykeius nov. gen. The Hornby Island fauna represents by far the most diverse deep-water assemblage ever described in the Late Cretaceous, particularly rich in hexanchiforms and squaliforms, providing new insights into the history of the deep-water settlement of this period.