The Early Ordovician bivalve assemblages of the Montagne Noire (France): palaeobiogeography, palaeoecology, and early diversification

 

Authors: Polechová M

Article in press: Received 19 June 2025; Accepted in revised form 22 October 2025; Online 30 November 2025

Keywords: Bivalves, Early Ordovician, Montagne Noire, France,

full text (PDF, 14.43 MB)

Export to RIS

 

Abstract

Early Ordovician bivalves from the Montagne Noire of France include eight taxa: Babinka prima Barrande, 1881, 1982, Coxiconchia guiraudi (Thoral, 1935), Ekaterodonta courtessolei (Babin, 1982), Noradonta redoniaeformis (Thoral, 1935), Redonia michelae (Babin, 1982), Modiolodon sp. (Thoral, 1935), Synek thorali (Babin, 1982) and Thoralia languedociana (Thoral, 1935). They are recorded from the late Tremadocian Saint Chinian Formation, the early Floian La Maurerie Formation, the middle Floian Cluse de l'Orb and Foulon formations, and the late Floian Llandeyran Formation. They represent a high palaeolatitude bivalve assemblage dominated by heteroconchs and protobranchs and exhibit strong similarities to contemporaneous Moroccan fauna, with dominance of Redonia and Babinka. However, Tremadocian bivalves are generally scarce, with only twenty-one known genera. They display diverse ecological strategies, including infaunal deposit and filter feeders, semi-infaunal and epifaunal filter feeders, and byssate semi-infaunal filter feeders. Tremadocian bivalves exhibited highly restricted global dispersion, with the majority of genera being endemic. Although Babinka, Coxiconchia, and Pharcidoconcha achieved a somewhat broader distribution during the Tremadocian, they still remained confined to Gondwana and its peri-Gondwana margin. Nevertheless, the western Gondwana corridor played a role in facilitating some faunal exchange, despite the general limitations on bivalve migration during this period.