A MID-MIOCENE ICHTHYOFAUNA FROM THE WOOD MOUNTAIN FORMATION, SASKATCHEWAN, CANADA

The southern Saskatchewan mid-Miocene Wood Mountain Formation has been the basis of studies describing its mammalian and herpetofaunas; here we present the description of the fish material from the formation. The fauna, of probable Barstovian age, would have been isolated from the western side of the continent, in an area draining towards the northeast. Sixteen taxa are recognized to specific orders or lower taxonomic levels, although this number is approximate because some identifications are tentative. The fauna includes a lepisosteid (Lepisosteus), an amiine, a probable hiodontiform osteoglossomorph, a hiodontid (Hiodon), at least two unidentified cypriniforms and a leuciscine, three ictalurids (Ameiurus, Ictalurus, and cf. Noturus), an esocid Esox sp. more closely related to pikes than to pikerels, a possible moronid perciform, a centrarchid (cf. Pomoxis), two percids (including Stizostedion sp.), and an unidentified teleost. This fauna includes the earliest North American percids, the last occurrence of lepisosteid and amiine fossils in Canada west of the Great Lakes, and may constitute the earliest evidence of North American moronids. The assemblage is typical of well-oxygenated, lowland fluvial environments, and indicates a wide variety of substrates and flow strengths, as well as the presence of aquatic vegetation in the vicinity. Additionally, the fauna implies the nearby presence of turbid and deeper environments, suggesting that the area was an environmentally varied floodplain during deposition. The paleoenvironmental implications of this ichthyofauna are compatible with those of the herpetofauna: warm temperate to subtropical, with temperatures similar to those of northern Mississippi or southern Tennessee.