An interpretation of Cretaceous and tertiary biota in polar regions

Rich fossil floras and vertebrate faunas lived within the Arctic and Atarctic Circles during the Cretaceous and Paleogene. These occurrences seem explicable by the nature of the thermal environments in polar regions and by the physiological responses of plants and animals allied to those that lived there. There seems no need to invoke a lower tilt to the Earth's axis to provide greater warmth and light in polar regions to account for these fossil records.