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

Abstract

The study of an undescribed part of the El Pozo tracksite in El Castellar (Teruel, Spain) has revealed two new trackways made by small omithopods showing new evidences of basal ornithopod 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 in one of the trackways confirms that the dinosaur was a quadrupedal. Probably, the trackmaker dinosaur is a representative of the dryosaurid or of the basal Ankylopollexia clades. These tracks are smaller than those described for the Las Cermdicas site, also located in Teruel and in the same formation; consequently, these tracks from El Pozo site constitute some of the smallest ornithopod 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 dinosaurs.