LATITUDINAL CORRELATION OF TERRESTRIAL ECOSYSTEMS ACROSS THE WESTERN INTERIOR BASIN DURING THE ZENITH OF DINOSAUR DIVERSITY: HIGH-PRECISION U-PB ZIRCON GEOCHRONOLOGY FROM THE CAMPANIAN OF NORTH AMERICA

The Campanian (Late Cretaceous) dinosaur record is exceptionally rich throughout the Western Interior Basin of North America, preserved in terrestrial and shallow marine deposits that extend from Alberta to Texas. This widely distributed and enhanced fossil record provides a remarkable opportunity for examining the interrelationships between vertebrate and plant diversities, faunal provinciality and climatic and eustatic changes that impacted the terrestrial ecosystems. However, a lack of reliable temporal context has hampered a full integration of fossil and paleoenvironmental records and hindered the elucidation of patterns of biotic evolution in this critical time interval.

We present high-precision U-Pb geochronologic data from bentonite layers intercalated with Campanian dinosaur-bearing strata that occur ca. 1500 kilometers apart across the Western Interior Basin. The results establish a new high-resolution chronostratigraphy for the corresponding formation in the Dinosaur Provincial Park (southern Alberta, Canada) and allow direct latitudinal correlation with coeval strata of the Kaiparowits Plateau (southern Utah, USA). A thorough assessment of sediment accumulation rates – including depositional hiatuses – throughout the studied sections in the context of a refined geochronologic framework allows the temporal and special distributions of key fossil assemblages to be carefully examined and the tempo of faunal turnovers to be better understood. Preliminary results indicate a close temporal correlation between the most fossiliferous stratigraphic intervals of the Dinosaur Provincial Park and the Kaiparowits Plateau.