Jurassic Coastal Park: A great diversity of palaeoenvironments for the dinosaurs of the Villar del Arzobispo Formation (Teruel, eastern Spain)

Abstract

The Villar del Arzobispo Formation, cropping out in the western Peñagolosa sub-basin (Late Jurassic, eastern Spain), includes abundant dinosaur tracksites and bones, which occur in diverse mixed siliciclastic and carbonate facies deposited from shallow marine to coastal and alluvial paleoenvironments. The lower part of the unit, mainly composed of bioclastic and oolitic limestone, was deposited in an inner carbonate platform, which underwent episodic subaerial exposure and siliciclastic inputs from the emergent areas, and includes scarce dinosaur tracks. This environment evolved into a siliciclastic coastal and alluvial plain that was crossed by channels and affected by periodic flooding events, producing the deposition of splay lobes. Upward, the siliciclastic coastal and alluvial deposits are interbedded with inter- to supratidal limestone beds. These tidal and coastal deposits show the highest abundance, diversity and best preservation of dinosaur tracks and bones of the unit. This setting gradually evolved upward into an inner carbonate platform, producing the deposition of shallow marine bioclastic and oolitic limestone, which includes very scarce dinosaur tracks. The highest abundance, diversity and best preservation of theropod, sauropod, thyreophoran and ornithopod tracks occur at the top of tidal carbonate beds. Tracks also occur in the siliciclastic coastal and alluvial plain deposits, especially in the flood plain deposits, preserved, mainly, as infillings or natural casts. Additionally, very scarce and poorly-preserved tracks occur at the top of shallow marine carbonate beds. Bones may be rticulated and/or associated in the flood plain deposits, whereas they are isolated and dispersed in the splay lobe deposits. Although this unit has been previously assigned to the Tithonian-Berriasian, the analysis of larger benthic foraminifera suggests a Kimmeridgian-Tithonian age for the Villar del Arzobispo Formation. This is consistent with the dinosaur assemblages present in the unit, which are strongly related to other European Late Jurassic faunas.