A sauropod-dominated tracksite from Rubha nam Brathairean (Brothers’ Point), Isle of Skye, Scotland

Abstract

Middle Jurassic dinosaur fossils are exceedingly rare, but new discoveries from the Isle of Skye, Scotland, are beginning to fill this gap. We here describe a new dinosaur tracksite found in the Lealt Shale Formation (Bathonian) of the Great Estuarine Group at Rubha nam Brathairean (Brothers' Point) on Skye. The site preserves an abundance of small sauropod manus and pes prints and several isolated and broken medium-to-large tridactyl footprints. The main site occurs on a single horizon of shaley limestone that formed in a lagoonal environment. The sauropod tracks are tentatively assigned to the ichnotaxon Breviparopus due to the narrow gauge of the trackways, the digital characteristics of the pes, and the ratio of heteropody observed between the manus and the pes. A theropod trackmaker is inferred for some of the tridactyl impressions with several indicative of the ichnotaxon Eubrontes . This new site strengthens the inference, originally based on a previously discovered locality near Duntulm Castle (Duntulm Formation) in northern Skye, that sauropods habitually spent time in lagoons during the Middle Jurassic. Supplementary material : The photogrammetric model of track BP2_40 and associated metadata and photographs are available at https://doi.org/10.6084/m9.figshare.c.4046390

Novel track morphotypes from new tracksites indicate increased Middle Jurassic dinosaur diversity on the Isle of Skye, Scotland

“…The only major dinosaur clade that is not represented at the site is Sauropoda. The lack of sauropod tracks at these sites may be environmental as the sauropod tracks previously described from Skye [24,25] were made in shallow lagoons and not on subaerially exposed mudflats (the depositional environments inferred for the BP1 and BP3 sites). Although sauropod tracks are not present at BP1 and BP3, the track morphologies observed at these sites (which are located in close stratigraphic and geographic proximity to one another) illustrate a diverse Middle Jurassic dinosaur fauna for Skye.…”

“…Notably, BP1 and BP3 lack any evidence of sauropod tracks. However, a recently described tracksite from slightly lower in the stratigraphy at Brothers' Point is dominated by them [25] as is another tracksite from the slightly younger Duntulm Formation [24]. When we consider the three geographically and temporally close tracksites at Brothers' Point together, we see representatives from all major dinosaur clades (theropods, sauropods, and ornithiscians).…”

“…It may be possible that one or more of these beds preserve extensive tracksite surfaces across hundreds of meters of lateral continuity, but which are not discernable at outcrop scale because of the patchy nature of the exposures and the extensive metamorphism around Brothers' Point. Indeed, other track-bearing surfaces appear slightly lower in the section at Brothers' Point Site 2 which is located immediately above the '6 m sill' in Beds 24 and 25 [25].…”

Fossil heritage conservation in Scotland

“…Internationally signifi cant fi nds, refl ecting the variety and richness of fossils and their preservation in Scotland, are continually being made. This is exemplifi ed by the recent discovery of tracksites within the Middle Jurassic sequences of Skye (de Polo et al, 2018).…”

First dinosaur from the Isle of Eigg (Valtos Sandstone Formation, Middle Jurassic), Scotland

“…Finds from other formations within the Great Estuarine Group and underlying units include a theropod limb bone , an isolated theropod tooth (Young et al 2019), isolated sauropod teeth (Barrett 2006), and a thyreophoran proximal ulna and radius (Clark 2001). Dinosaur ichnofossil tracks range from isolated tracks on loose boulders (from the Valtos Sandstone Formation, Clark & Gavin 2016, from other formations in the Great Estuarine Group, Andrews & Hudson 1984;Clark et al 2005), to extensive in situ trackway sites (from the Valtos Sandstone Formation, Marshall 2005, and from other formations in the Great Estuarine Group, Clark et al 2004;Marshall 2005;Brusatte et al 2016;dePolo et al 2018dePolo et al , 2020.…”