Soft-bodied fossils from the roof shales of the Wigan Four Foot coal seam, Westhoughton, Lancashire, UK

Abstract

Exceptionally preserved fossils are described from the Westhoughton opencast coal pit near Wigan, Lancashire, UK (uppermost Westphalian A, Lower Modiolaris Chronozone, regularis faunal belt). The fossils occur within sideritic concretions in a 1.5-metre zone above the Wigan Four Foot coal seam. Arthropods dominate the fauna and include arachnids, arthropleurids, crustaceans, eurypterids, euthycarcinoids, millipedes and xiphosurans. Vertebrates are represented by a single palaeoniscid fish, numerous disarticulated scales and coprolites. Upright Sigillaria trees, massive bedded units and a general lack of trace fossils in the roof shales of the Wigan Four Foot coal seam suggest that deposition of the beds containing these concretions was relatively rapid. Discovery of similar faunas at the equivalent stratigraphic level some distance away point to regional rather than localized controls on exceptional preservation.