The Cretaceous Araripe Basin Dinosaur Tracks and Their Paleoenvironmental Meaning

Fossil footprints are generally recognized by morphological features from the feet registered on the unconsolidated substrate; therefore, they can also be understood as biogenic primary deformation structuresDeformation structures. The footprints can be found in the bedding surface and as cross-sectionCross sections deformations of the strata. Then, the substrate properties and the animal’s behavior allow for a wide range of track morphologies. The main modes of footprint preservation can thus be evaluated as the relationship between the substrate and the lower surface of the feet. In the Araripe Basin, both kinds of preservation are found in the Mauriti, Rio da Batateira, Crato, and Exu formationsExu formation. In the Mauriti FormationMauriti formation, the footprints are imprints in the bedding surface of fine to coarse-grained sandstones. The cross-section footprintsCross-section footprints occur in the Rio da Batateira, Crato, and Exu formationsExu formation. These footprints are produced by foot pressure on a depositional surface, and transmitted downward inside a bed or a bed set. In some cases, they are difficult to recognize, as they can be misinterpreted as load or liquefactionLiquefaction inorganic features related to sediment compaction, usually triggered by earthquakes and not to tramplingTrampling by terrestrial vertebrates. They are in reality load castsLoad casts produced by dinosaur tramplingDinosaur trampling, allowing evaluation of substrate consistencySubstrate consistency besides the potential trackmaker identification. The temporal and environmental contexts of the dinosaur footprints from the Araripe Basin include the dinosaur tramplingDinosaur trampling in fluvialFluvial sand barsSand bars, floodplainsFloodplain, deltas, and saline-alkaline lakeAlkaline lakes borders.