Paleooecology of the Judith River Formation (Campanian) of Dinosaur Provincial Park, Alberta, Canada: Evidence from vertebrate microfossil localities

Abstract

A survey of the stratigraphic disriubtion of 34 taxa of vertebrates in Judith River Formation (Campanian) of Dinosaur Provincial Park, Alberta, Canada, based on screenwashed samples from 25 vertebrate microfossil localities showed that many vertebrates have a non-random distribution in these beds. Amiidae gen. unident., holostean A, Coriops, teleost D, teleost gen. unident., Scapherpeton Opisthotriton, and frogs decrease in abundance through all or most of the stratigraphic interval exposed in Dinosaur Park; Myledaphus, Atractosteus, holostean B, Belonostomus, Champsosaurus, Leidyosuchus, and ceratopsians increase in abundance through this interval; Hybodus, Basilemys, and Paratarpon are found only in the upper part of the exposures; Thescelosaurus is restricted to the lower exposures; Troodon is encountered more frequently in localities low in section, and Paralbula and Aspideretes increase in abundance in channel deposits. These stratigraphic distributions reflect ecological zonation of the coastal plain in which the beds were laid down; the animals that have their horizons of greatest abundance in the upper beds would have been members of a zone located near the shoreline, and the animals that have their horizon of greatest abundance low in section would have been members of a zone located relatively more inland. These two paleoecological assemblages can be further subdivided into aquatic and terrestrial paleocommunities according to interpretations about the mode of life of the individual taxa. The terrestrial paleocommunities are similar to those of the Late Maastrichtian in that ceratopsians occupied the most near-shore areas of the coastal plain and hypsilophodonts were present in the areas of the coastal plain farthest from shore.