Vertebrates from the Wood Bay Group and the position of the Emsian-Eifelian boundary in the Devonian of Vestspitsbergen

This paper deals with various vertebrates from the Verdalen Member of the Stjørdalen Formation of the Wood Bay Group, Vestspitsbergen, or layers presumably belonging to this member, including the thelodont scales Amaltheolepis winsnesi n.g., n.sp. (earlier known from a locality in Sørkapp Land), the heterostiid brachythoracid Herasmius granulatus n.g., n.sp. and the porolepiform crossopterygian Heimenia ensis n.g., n.sp., the latter with scales intermediate in some ways between those of Porolepis on the one hand, and the Holoptychiidae on the other. Amaltheolepis and Herasmius are not yet known to occur outside Vestspitsbergen; Heimenia is represented in a Devonian material from Anderson River, Northwestern Canada and perhaps also in the Placoderm Sandstone of Poland. A critical appraisal of the arthrodire faunas of the Wood Bay Group shows that most of the earlier recorded occurrences of Homostius and Heterostius in these layers pertain to euleptas-pid brachythoracids, that the Heterostiidae and Homostiidae are also represented, but only in the Stjordalen Formation, and that the youngest member of the Euleptaspididae, occurring in the Stjordalen Formation, may be closely related to another euleptaspid in the Upper Emsian Heisdorf Beds of the Rhinish sequence (which occurs in association with Ohiolepis scales). The palaeontological evidence may indicate that the Wood Bay Group does not belong to the Lower Devonian in its entirety but includes Middle Devonian strata in its uppermost part.