Periglacial Environments & Polar Dinosaurs

Sedimentary structures in the Early Cretaceous Wonthaggi Formation of southeastern Australia appear to have formed in the presence of seasonally frozen ground indicating a frigid climate. Histological analysis of a hypsilophodontid dinosaur bone found 3 meters stratigraphically above one of the seasonally frozen ground horizons shows that this individual never experienced a period of slow growth as would have been the case had it not been active during the polar winter. Another southeastern Australian hypsilophodontid had enlarged optic lobes on the brain, evidently an adaptation for enhanced visual acuity during the winter darkness, facilitating active foraging at that time.