Alison M. Murray

Snakehead fishes (family Channidae) are represented by two extant genera, Channa, in Asia, and Parachanna, in Africa. Both genera are known from Eocene fossils in their respective continents. A phylogenetic analysis using osteological characters for the fossil taxa and numerous extant species indicates that the two genera are reciprocally monophyletic and endemic to each land mass. Because channids are restricted to fresh waters, their presence in Africa and Asia in the Eocene, when these two landmasses were not connected by terrestrial routes, indicates they must have either evolved prior to the separation of continents and the lineage is extremely old for a percomorph, which is unlikely, or that an alternate route was present betweenAfrica and Asia during the Eocene or earlier. Since migration between Asia and Africa through Europe would have been blocked by the Tethys Sea until the Miocene, an island arc facilitating migration is proposed. This supports previous suggestions of an Early Cenozoic connection between Africa and Asia.

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.

13th annual meeting, Drumheller, Alberta May 1-3, 2026

Late Cretaceous acanthomorph fishes are well represented in freshwater vertebrate microfossil localities in the Western Interior of North America but are not well known from articulated specimens. Microfossils—isolated disarticulated elements—provide data on diversity and distribution but can be difficult to assign to known lineages. Articulated specimens are needed to evaluate the evolutionary relationships of early acanthomorphs, but these are rarely preserved in fluvial beds, limiting our understanding of the taxa present in these environments. An exceptional freshwater locality that preserves a diverse assemblage of small articulated specimens is Pisces Point sampling the Scollard Formation of Alberta, Canada. Known taxa in the locality include two osteoglossomorphs, an esocid, the percopsiform (Acanthomorpha) Lindoeichthys albertensis Murray et al., 2019, and the otophysan Acronichthys maccagnoi Liu et al., 2025. Here we describe two additional acanthomorph fishes: a polymixiiform tentatively in family Boreiohydriidae, and a percomorph of uncertain relationships. These specimens, along with the previously named Pisces Point percopsiform, indicate that at least three distantly related acanthomorph lineages were present in fresh waters of North America by the late Maastrichtian, and increase our understanding of the acanthomorph evolutionary and geographic diversity prior to the end of the Cretaceous.

Belonostomus longirostrisis was named for an isolated jaw fragment from freshwater Upper Cretaceous (Campanian) sediments of the Dinosaur Park Formation of Alberta, Canada. Following the description of the Albertan species, numerous isolated cranial and postcranial elements have been collected from the Dinosaur Park Formation and assigned to B. longirostris , despite the material not overlapping with, and therefore not being comparable to, the holotype. This includes two partial skulls that lack jaws. These two skulls were assigned to the genus based on their clear aspidorhynchid affinities including ganoine‐covered dermal bones, and lack of other known taxa from the locality to which they could be ascribed. The two skulls were scanned with micro‐computed tomography (μ‐CT) to allow description of the cranial elements and their internal structure. The bones of the dermal skull roof are almost entirely fused together, ornamented with conspicuous ridges and tubercles, and bear a pair of supraorbital sensory canals along the lateral sides. Internally, many bones of the skull are fused together, with only a few elements that can be consistently isolated in the μ‐CT scans. Notable discoveries in this material include extensive enclosed cranial sensory canals, no fusion between the basioccipital and first vertebra, the anterior myodome restricted to the sphenotic region with complete lack of a posterior myodome, and a canal, presumably for the jugular vein, that does not connect with the trigemino‐facialis chamber. These last two features are important in that they would exclude Aspidorhynchidae from belonging to Teleostei.

During the Late Cretaceous, the coastline of the epicontinental Western Interior Seaway in North America fluctuated in position, temporarily replacing some terrestrial ecosystems with shallow marine habitats.In southeastern Alberta, the uppermost portion of the Dinosaur Park Formation (Belly River Group, late Campanian) preserves one of these transgression–regression cycles in a marine wedge named here as theJohnson Unit. We report the stratigraphy of the unit based on nine stratigraphic sections over several kilometres of exposure. We describe a diverse assemblage of marine vertebrates from the Johnson Unit, represented by microfossils from a surface collecting survey. Our sample includes 1431 specimens, which we assign to 40 taxa. We identify eight new actinopterygians from the unit: Belonostomus longirostris, Amiidae indet.,Elopiformes indet., Horseshoeichthys sp., Enchodus gladiolus, Dercetis cf. D. magnificus, Acanthomorpha indet., and teleost indet. type O. The acanthomorph specimens, which include isolated spines and centra, represent the second marine Cretaceous acanthomorph reported from Alberta, and the highly ornamented spines are unlike any previously described. We revise several chondrichthyan identifications from previous authors and describe partial tooth plates from the chimaeriform Ischyodus bifurcatus for the first time in Canada. Compared to earlier samples from the same unit that were collected using screen-washing, our sample has ahigher diversity of actinopterygians and tetrapods. We identify several taxa to lower taxonomic levels using more complete specimens. These differences are attributed to our use of surface collection; this method allowed novel biogeographic and taxonomic insights.

Otophysans, known for their enhanced hearing enabled by the complex Weberian apparatus, comprise two-thirds of extant freshwater fish species. Previously, they were thought to have originated in fresh water before the breakup of Pangea, implying a nearly 80-million-year gap between the origin and oldest known fossil. However, the discovery of a Late Cretaceous freshwater otophysan challenges this view. Integrating fossil, morphological, and genomic data, we estimate a younger crown group origin of ~154 million years ago. Notably, ancestral range and habitat reconstructions indicate marine origins for the otophysan crown groups, with at least two transitions to fresh water. Functional simulations of the Weberian ossicles of this fossil suggest that the distinctive hearing capabilities of otophysans evolved in conjunction with fusion of hearing ossicle parts and freshwater adaptations.