Teleost centra from uppermost Judith River Group (Dinosaur Park Formation, Campanian) of Alberta, Canada

Abstract

The diversity and distribution of teleosts in the Dinosaur Park Formation of Alberta, Canada, is evaluated on the basis of precaudal centra. In order to avoid the erection of redundant taxa, and to include all teleost precaudal centra in a single system, a parataxonomic system is erected. Fifteen distinct basal groups, termed morphoseries, are described. Growth-related changes and serial variation along the column are taken into account in defining these groups, so each morphoseries is interpreted as representing a distinct, low-level taxon of teleost. One of the morphoseries could be identified as hiodontid and two as acanthomorph on the basis of derived character-states. This is the first Cretaceous record of hiodontids in North America. In addition, elopomorphs, clupeomorphs, salmoniforms, and osteoglossoforms are recognized on the basis of general similarity with the precaudal centra in extant members of these groups. Two teleosts of intermediate level of evolution, but of uncertain relationships, are also present. Differences in the stratigraphic distributions of the morphoseries allow two distinct assemblages of teleosts to be recognized in the formation. One is present in fluvial-dominated localities of the Dinosaur Park Formation, the second in a complex of mud-filled channels in the Lethbridge Coal Zone. The paleoecological complexity present in the formation, and the high level of diversity of teleosts in these beds, emphasizes the importance of including disarticulated remains in studies of the diversity and distribution of teleosts in the Cretaceous.