A late Coniacian ceratioid dinoflagellate cyst, Odontochitina octopus sp.nov., from the Kanguk Formation, Canadian Arctic

Abstract

Anew species of dinoflagellate cyst, Odontochitina octopus sp.nov., is described from the Upper Cretaceous Kanguk Formation of the Sverdrup Basin, Canadian Arctic Islands. The features that support the proposal of this new species also necessitate the emendation of the genus. Odontochitina octopus is a large, cornucavate, and ceratioid cyst with four finger-like terminations on the apical horns and two terminations on both the postcingular and antapical horns. These finger-like terminations are unique to this new species and are formed by the detachment of the paraplates at mid-length of each horn. All other features of O. octopus conform with the previous description of the genus. In the Family Ceratiaceae four plates form the apical horn, whereas two plates are involved in both the postcingular and antapical horns. In O. octopus the mid-length detachment of the horn-forming paraplates seems to have developed the finger-like terminations. Since the nature and amount of pores and perforations in other species of Odontochitina are variable and possibly linked to changes in the environment, the presence of the multiple-fingered O. octopus in a single widespread horizon might also be indicative of short-lived unusual environmental conditions. At this horizon, which has been dated as late Coniacian by the ammonite Scaphites depressus Reeside, the palynomorph assemblage is highly dominated by marine species.