Middle Albian (lower Cretaceous) gastroplitinid ammonites and dinoflagellates from the Christopher Formation (Dragon Mountain, Axel Heiberg Island, Canadian Arctic Islands) and a revision of the genus Pseudogastroplites Jeletzky, 1980

A large sample of excellently preserved ammonites from concretions concentrated at a single horizon near the base of the Macdougall Point Member of the Christopher Formation (Aptian-Albian age; Early Cretaceous) is the basis for recognizing a new species of the boreal ammonite genus Pseudogastroplite (P. draconensis). The dimorphic nature of the genus is established, two variants are recognized (P. draconensis var. robusta and P. draconensis var. gracile), and the generic diagnosis is emended. Retention of the genus Pseudogastroplites Jeletzky, 1980 as distinct from Gastroplites McLearn, 1930 is proposed. The concretions also yield Pseudopulchellia flexicostata (Imlay, 1961), inoceramid bivalves, fish remains, and a palynological flora, and are dated as late middle Albian.