"Oxalaia" is known from the Alcântara Formation, a geological formation in northeastern Brazil. This formation dates to the Upper Cretaceous Period, sometime between 100.5 to 93.9 million years ago. Back then, the environment of the formation had a wet climate. There were large tropical forests made of plants like conifer trees, ferns, and horsetails. These forests were surrounded by an arid, or dry, landscape.