Although tracks of dinosaurs are well known from Upper Jurassic sediments, tracks of non-dinosaurian vertebrates are fairly rare. The Upper Jurassic Lastres Formations of Asturias in northern Spain contain many vertebrate tracksites that include footprints and trackways of non-dinosaurian tetrapods. Several of these tracks are natural casts of pentadactyl to tridactyl footprints with digits connected by arched structures. The digits are short with deep scratch marks oriented anteriorly. The Asturian tracks show a high degree of morphological similarity to other specimens previously described as possible turtle tracks. Observations from extant turtle trackways show some surprising similarities with the fossil material. The tracks are here interpreted as having been made by turtles partially buoyed by water or by turtles walking in a slightly wet subaerial environment.

Key words: Testudines, turtle tracks, gait pattern, experimental ichnology, Jurassic, Asturias.

Marco Avanzini [avanzini@mtsn.tn.it] and Michele Menegon [menegon@mtsn.tn.it], Museo Tridentino di Scienze Naturali, via Calepina 14, I−38100 Trento, Italy; José Carlos García−Ramos [jcgramos@geol.uniovi.es] and Laura Piñuela lpinela@geol.uniovi.es], Museo del Jurásico de Asturias, San Telmo, San Juan de Duz, Colunga, Asturias, Spain and Departamento de Geología Universidad de Oviedo, C/Jesús Arias de Velasco, s/n 33005 Oviedo, Asturias, Spain; José Lires and Luis Alfonso Fernández, Departamento de Geología Universidad de Oviedo, C/Jesús Arias de Velasco, s/n 33005 Oviedo, Asturias, Spain.