Dinosaur trackways from the Upper Cretaceous Oldman and Dinosaur Park formations (Belly River Group) of southern Alberta, Canada, reveal novel ichnofossil preservation style

Recent discoveries of dinosaur trackways in the Upper Cretaceous Oldman and Dinosaur Park formations (Belly River Group) of southern Alberta reveal a novel preservation style of ichnofossils, termed 'concretionary tracks.' These tracks, attributed to hadrosaurs, are found as sideritic or calcareous concretions protruding from fine-grained deposits. Unlike typical track fossils, these concretionary tracks exhibit microscopic convoluted laminations and suggest formation in wet paleoenvironments where groundwater rich in dissolved carbonates flooded depressions left by dinosaurs. As the water evaporated, minerals precipitated and mixed with clastic material, filling the tracks either partially or completely. Geochemical analyses indicate cementation occurred rapidly after burial, possibly due to microbial activity. Modern erosion exposes these tracks but also causes them to break apart quickly, altering their diagnostic shape. This discovery suggests dinosaur tracks may be more common than previously thought but are transient in badlands environments.

Therrien, F., Zelenitsky, D. K., Quinney, A., & Tanaka, K. (2015). Dinosaur trackways from the Upper Cretaceous Oldman and Dinosaur Park formations (Belly River Group) of southern Alberta, Canada, reveal novel ichnofossil preservation style. Canadian Journal of Earth Sciences, 52(8), 630–641. https://doi.org/10.1139/cjes-2014-0168