The Ureocrinus bockschii bed of Trearne Quarry SSSI (Mississippian, Lower Carboniferous), north Ayrshire, Scotland

Trearne Quarry in north Ayrshire, SW Scotland, is a Brigantian (Mississippian) age Site of Special Scientific Interest (SSSI) with a diverse marine biota. The crinoids are notable, many species being known from well-preserved cups and columns showing pitted infestations. The horizon considered herein is named, informally, the Ureocrinus bockschii bed. The named species is a dendrocrinid cladid that is the most common species from this site. The calyx seems to have had an inherent robustness as they are more common than any other crinoid species. The U. bockschii bed yields only rare disarticulated calyx plates of other crinoid species. Pits, Oichnus simplex Bromley, in stems are more likely to be domiciles of unmineralized infesting organisms rather than evidence for gastropod parasitism or predation. Crinoid attachment structures are rare. The associated fauna is limited, including brachiopods, corals (Othoceras sp.), bryozoans (Rhabdomeson sp.), the bellerophontid Euphemites urii (Fleming) and rare fishes, Petalodus acuminatus (Agassiz).