Description of large, well‐preserved Enchodus specimens from the Bearpaw Formation of Alberta, Canada

Fishes of the genus Enchodus were abundant and cosmopolitan in the Late Cretaceous, but are primarily known from isolated remains in Canada. Four well-preserved fish skulls were recovered in recent years from ammolite mines sampling the Bearpaw Formation of Southern Alberta, and are here referred to Enchodus petrosus Cope, 1874. One specimen is disarticulated, allowing the description of the lateral braincase for the first time in this species. The most complete articulated specimen is also the largest articulated skull yet described from the genus, resulting in an estimated 1.5 m total length for the animal. Another skull is preserved in three dimensions and was CT scanned, allowing the identification of a fossa, rather than the expected fenestra, for the insertion of the mandibular fang on the premaxilla. An associated caudal fin is similar to one described from the Pierre shale, with a large laterally positioned scute slightly anterior to the caudal skeleton. Isolated teeth from the Bearpaw Fm are identified as Enchodus cf E. gladiolus, supporting the sympatry of the two species in the Bearpaw Sea. These specimens expand our understanding of the ichthyofauna of the Bearpaw Formation, since only three fish species are previously documented from the formation.