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

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.

KEYWORDS:

• Deep-sea elasmobranchs
• Late Cretaceous
• high diversity
• new taxa

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Acknowledgments

With special thanks going to: from K’omoks First Nation – Chief Councillor Nicole Remple and council, Ken Price for making introductions; from Comox, B.C. Noel and Pamela Chaney, Dr. Dirk Meckert; from Courtenay, B.C. Doug Embrey, Dan Bowen, Russell Lang, Joe Morin, Tim O’bear; from Hornby Island B.C. Beryl Geppert, Dr. Hilary Howard, Stevi Kittleson, Valérie Pagnier, for her translations, Beryl Geppert, Dr. Hilary Howard, Rob and Amanda Zielinski (Hornby Island Diving), Neil MacDaniel (underwater cinematographer), Otto Lam of Victoria, B.C., Mowisaht (Ernie) and Darlene Smith of Ehattesaht, Nuu-Chah-Nulth First Nation for their help initiating introductions with K’omoks First Nation. Leise Verboom of Parksville, B.C. for all her photocopy work. Dr. Chris Harvey Clarke (Dalhousie University, Halifax, N.S.), Otto Lam of Victoria, B.C., Dr. Peter Mustard (Simon Fraser University), Dr. Peter Ward (University of Washington), Leise Verboom of Parksville, B.C. William Hessin, Don Ball, Peter Lowe and Jean ‘Devanshu’ J.R. Domingue (Hornby Island Fossil Shark Team Member) for all their back-breaking work in collecting Hornby Island shark material, plus for making part or all their discoveries (from throughout B.C.), freely available to science for study, and especially for their Friendship and team spirit; The authors particularly want to thank Chantal Cazevieille and Alicia Caballero-Megido for their help in the scan photographing process of a large part of the specimens from Hornby Island, in the CRIC service (Montpellier, France). The photographs of larger specimens were made by two of the authors in Montpellier (HC, SA). A lot of thanks to Dr. Jorge D. Carrillo-Briceño, who kindly provided photos of the type of Chlamydoselachus tobleri Leriche, 1928. We wish to thank G. Dyke (Editor), T. Cook (Penn state University, USA) and an anonymous reviewer for the detailed reviews that significantly improved the quality of this work.

Disclosure statement

No potential conflict of interest was reported by the authors.