Grallator theropod tracks from the Late Jurassic of Asturias (Spain): ichnotaxonomic implications

Abstract

The MUJA (Museo del Jurásico de Asturias, Jurassic Museum of Asturias) has an interesting collection of theropod tracks that show similarities with the ichnogenera assigned to the Eubrontes-Grallator plexus. In this paper we describe in detail the morphology of 21 specimens recovered from different localities on “The Dinosaur Coast” of Asturias, plus four specimens preserved in outcrops in the sea cliffs of Les Vinaes (Villaviciosa). All the specimens are from the outcrops of the Lastres Formation, which is Kimmeridgian in age. The general morphology of the tracks, the footprint length-width ratio, the mesaxony, low divarication of the digits (II-IV) and the absence of hallux and metatarsophalangeal impressions suggest that the tracks are more similar to Grallator than to any other theropod ichnotaxa. Geometric morphometric analysis (principal component analysis, PCA) based on 2D landmark techniques suggests that they differ from Kalohipus bretunensis (as yet the only Grallator-like ichnotaxon described in the Iberian Peninsula) mainly in the divarication angles and in the projection of digit III