CRETACEOUS DINOSAUR-BEARING FORMATIONS: PREDICTION AND IMPLICATIONS FOR FOSSIL BIAS ESTIMATION

Every environment contains a specific set of conditions that act on fossil remains, representing the combined influence of local conditions (e.g. landscape, precipitation, temperature etc.). As biomes shift in response to macro-scale change, the nature and distribution of preservational regimes also vary, creating cascading effects through the diagenetic processes associated with particular environments. Here, we outline a novel approach for evaluating the impact of environmental agents on the fossil record, revealing whether potentially suitable environments made it into the geological record. We used the rich dinosaur record of the latest Cretaceous (Campanian and Maastrichtian) of western North America as a case study, a spatiotemporal window that has been the focus of a large body of research, reflecting its high-resolution stratigraphy and well-sampled fossiliferous sites. These data were extracted from the Paleobiology Database and combined with a new high-resolution global atlas of palaeogeographic maps. A HadCM3 coupled global climatic model was run on these digital elevation models (DEMs) in order to provide climatic model outputs of several physical parameters (e.g. temperature and precipitation) during these Cretaceous stages. The distribution of dinosaur fossils is spatially correlated with areas with a high precipitation regime. Hotspot analysis recognised several highly likely source areas for dinosaur fossils. These “hot spots” correspond to some long known dinosaur formations in North America (e.g. Dinosaur Park Formation in Canada). Because climate is a powerful driver of sedimentation we have used climatic envelopes, together with DEMs and basin drainage analysis reconstruction of palaeo-rivers to produce predictive maps of lithofacies suitable for fossilisation. These virtual taphofacies are an invaluable and new tool that can be used to evaluate the impact of bias in the fossil record.