A wildfire origin for terrestrial organic debris in the Cretaceous Santana Formation Fossil Lagerstätte (Araripe Basin) of north-east Brazil

The late Early Cretaceous Santana Formation fossil Lagerstätte of north-east Brazil’s Araripe Basin is known for its diverse aquatic vertebrate assemblage, but little is known of the palaeoenvironment of the surrounding hinterland of the basin. Isolated gymnosperm tracheids in acid-resistant residues from concretions of Romualdo Member of the Santana Formation are composed of fusain consistent with a wildfire origin. Fusain debris probably entered the Araripe Basin as fallout from wind-blown ash. A wildfire origin for the organic debris is consistent with palaeoclimatic interpretations that indicate an arid hinterland for the Araripe Basin during the mid Cretaceous.

► Fusain is reported for the first time from the Santana Formation of Brazil. ► The fusain is derived from wind blown ash from gymnosperm forest fires. ► This is the first time wildfire has been recognised as a component of Araripe Basin ecosystems.