The Duntulm sauropod tracksite and environmental partitioning in Middle Jurassic dinosaurs on the Isle of Skye, Scotland

Abstract

Dinosaur fossils from the Isle of Skye (Scotland, UK), particularly the abundant trace fossil record, provide a window into dinosaur evolution during the poorly known Middle Jurassic. Here we present a comprehensive description of the Duntulm tracksite from Cairidh Ghlumaig Bay, using aerial photography to provide whole site maps, catalogue the tracks, and identify trackways. The tracksite is located in rocks deposited in a shallow lagoonal environment and is dominated by small‐ to medium‐sized (<75 cm) sauropod footprints spanning several preservation styles, from casts with details of toes to impressions with less distinct features. Several short, narrow‐gauge trackways indicate that the sauropods were moving with a walking gait and the wide range of orientations of the trackways does not indicate any gregarious behaviour. Sparse, isolated theropod footprints are also present along the Duntulm coastline. The abundance of sauropod footprints at this locality prompts an examination of the substrate preferences of Skye's dinosaurs. We surveyed all currently known dinosaur tracks from the island and statistically analysed the relationship of trackmaker with substrate. This analysis indicates that Skye's sauropods had a preference for lagoonal substrates whereas ‘non‐sauropod’ dinosaurs (theropods, thyreophorans and ornithopods) are more abundant in subaerially exposed mudflats. We argue that this signal is robust, but this pattern can be further tested as more footprints are discovered on Skye.