On small quadrupedal ornithopod tracks in Jurassic-Cretaceous transition intertidal deposits (El Castellar, Teruel, Spain)

Resumen

The study of an undescribed part of the El Pozo tracksite in El Castellar (Teruel, Spain) has revealed two new trackways made by small ornithopods showing new evidences of basal ornithopods pes and manus track morphologies in the Jurassic-Cretaceous transition. The site lies within the Villar del Arzobispo Formation, which was deposited during the Tithonian-Berriasian in an environment under the influence of tides. The pes tracks are small tridactyl tracks, the digits are similar in size, and the heel is open and rounded. The presence of oval manus tracks in front of the tridactyl tracks is one of the trackways confirms that the dinosaur is a representative of the dryosaurid or the basal Ankylopollexia clades. These tracks are smaller than those described for the Las Cerradicas site, also located in Teruel and in the same formation; consequently, these tracks from El Pozo site constitute some of the smallest ornithopods trackways with quadrupedal locomotion ever described in the world. In addition, in the same tracksite bed, there are some poorly preserved tracks attributed to big quadrupedal dinosaur