title: An Ordovician variation on Burgess Shale-type biotas.
abstract: The Cambrian Burgess Shale-type biotas form a globally consistent ecosystem, usually dominated by arthropods. Elements of these communities continued into the Early Ordovician at high latitude, but our understanding of ecological changes during the Great Ordovician Biodiversification Event (GOBE) is currently limited by the paucity of Ordovician exceptionally preserved open-marine faunas. Here we clarify the early stages of the GOBE by describing a new open-marine Konservat-Lagerstätte from the Early Ordovician of Wales. The Afon Gam Biota includes many lineages typical of the Cambrian Burgess Shale-type biotas, but the most abundant groups were sponges, algae and worms, with non-trilobite arthropods being unexpectedly rare. Labile tissues occur abundantly in the sponges and are also present in other groups, including brachiopods and hyoliths. Taphonomic biases are considered and rejected as explanations for arthropod rarity; the preserved biota is considered to be an approximation to the original community composition. We note that other exceptionally preserved communities in the Welsh Ordovician are also sponge-dominated, suggesting a regional change in benthic ecology during the early stages of the GOBE.
authors.affiliation: 1] Chatsworth, Spa Road, Llandrindod Wells, Powys, LD1 5EY, UK [2] Nanjing Institute of Geology and Palaeontology, Nanjing, China.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Botting
authors.affiliation: Chatsworth, Spa Road, Llandrindod Wells, Powys, LD1 5EY, UK.
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Muir
authors.affiliation: Department of Earth Science and Engineering, South Kensington Campus, Imperial College London, SW7 2AZ.
authors.forename: Naomi
authors.initials: N
authors.lastname: Jordan
authors.affiliation: 1 Hamilton Terrace, Shoscombe, Bath BA2 8ND, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Upton
mesh_terms: D000818:Animals; D001181:Arthropods / Q000033:anatomy & histology; D044822:Biodiversity; D058448:Biota; D053476:Extinction, Biological; D005580:Fossils; D011161:Porifera / Q000033:anatomy & histology