A Campanian ecosystem reconstruction through the geochemistry of enamel and amber

Analysis of the isotopic composition of Mesozoic vertebrate tissues has become increasingly common in recent years, allowing researchers to reveal otherwise obscure ecological dynamics of ancient ecosystems. This study extends isotopic analyses into new palaeoenvironments and taxa, helping to address longstanding questions concerning Mesozoic animal dietary preference and migration behaviour. We have measured multiple isotope systems in both tooth enamel and amber from the animals within the Campanian Dinosaur Park Formation in Saskatchewan, Canada. In Saskatchewan, this formation was deposited within a unique marginal marine ecosystem that differs from previously studied deposits in Alberta. The isotopic values of carbon, oxygen and strontium within vertebrate enamel, as well as hydrogen and carbon within amber, provide a glimpse of living conditions near the Western Interior Seaway. Through trace element ratios and Fourier Transform Infra-Red spectroscopy, we were able to assess diagenetic alteration. We suggest that coastal proximity heavily influenced the isotopic values seen within both animals and ambers, resulting in the general enrichment of multiple isotope systems. Our data provides a 87 Sr/ 86 Sr value for some of the Easternmost exposures of the Dinosaur Park Formation. We hope future studies can build off this dataset to understand what role coastal proximity played in Cretaceous animal behaviour. • First geochemical trophic study from the Dinosaur Park Formation in Saskatchewan. • Trace element data support preservation of a primary isotopic signature. • Coastal proximity is directly reflected in isotope values.