Taphonomic and sedimentologic interpretations of the dinosaur-bearing Upper Cretaceous Strata of the Prince Creek Formation, Northern Alaska: Insights from an ancient high-latitude terrestrial ecosystem

Several dinosaurian bonebeds occur within the Campanian–Maastrichtian portion of the Prince Creek Formation of northern Alaska along a 45 km stretch of the Colville River. These beds are characterized by the occurrence of bones from large numbers of juvenile to sub-adult dinosaurs entombed in a hydraulically incompatible fine-grained matrix. The skeletal elements show little evidence for articulation, though there is evidence for association. Further, the bones show little evidence of post-mortem alteration such as prolonged exposure to weathering, predation, or trampling. The sediments of the Late Cretaceous to Paleocene Prince Creek Formation represent a continental succession deposited on a high-latitude, low-gradient alluvial/coastal plain. Deposition occurred in trunk channels, on distributary-channel splay complexes, in interdistributary bays, and on floodplains. These bonebeds formed under unique paleoclimatic and paleogeographic conditions. Although mean annual temperatures on the coastal plain were higher during the deposition of the Prince Creek Formation than modern temperatures, the evolving Brooks Range orogenic belt formed the southern edge of the Colville basin, providing a high-latitude, cooler alpine environment in close proximity to these warmer lowland environments. Seasonal flow due to the combination of snow melt and alpine permafrost in the ancestral Brooks Range likely produced regularly occurring seasonal floods, which are the likely killing mechanism that resulted in the formation of these bonebeds.