Preservation of Dinosaur Footprints in Shallow Intertidal Deposits of the Jurassic-Cretaceous Transition in the Iberian Range (Teruel, Spain)

摘要

This article describes the sedimentological characteristics of dinosaur ichnites at three sites within the municipal area of El Castellar (in the Province of Teruel, Aragón, Spain): El Castellar (CT-1), El Pozo (CT-2), and Camino El Berzal (CT-3). These sites possess large concentrations of footprints made by quadrupedal (sauropod, stegosaurid and ornithopod) and bipedal theropod dinosaurs. Among the more than 800 documented footprints at CT-1 is a trail left by a large theropod, and at least one other made by a stegosaurid (the holotype of Deltapodus ibericus). CT-3 contains some of the largest sauropod footprints ever found in the Iberian Peninsula. The three sites lie within theVillar del Arzobispo Formation, which was deposited over the Tithonian-Berriasian period in an environment under tidal influence. Tidal carbonates host the largest number of footprints. Different footprint shapes and degrees of preservation are apparent, even within a single layer, reflecting the characteristics of the original sediment in which the footprints were made. The grain size and water content of the original sediment, primarily the micritic mud derived from the pellets when it contains some water, appear to have been the most important factors in determining the quality of the preserved prints. The presence of algal mats appear to have been less important, because the mats detected inside the massive or pelletoidal micrite were broken and deformed, andwould therefore not have invested the substrate with cohesion enough to favor footprint preservation.