Dipnoan diversity in the early Pennsylvanian of Scotland: new lungfish from the Lower Coal Measures of North Lanarkshire

Abstract

Only two lungfish have been recorded in the Scottish Coal Measures in the past one hundred and fifty years: Ctenodus and Sagenodus . Here we describe a suite of new lungfish specimens collected from sites in the Scottish Central Coalfield that represent a least four taxa: Sagenodus ; Conchopoma ; and two new forms Braccodus kerri gen. et sp. nov and Lanarkodus clarki gen. et sp. nov. These are part of an extensive vertebrate fauna recently discovered in colliery waste from mining the Upper and Lower Drumgray Coal. These coals lie within the Communis Chronozone and are of Langsettian age. The specimens are much smaller than those found previously in the Scottish Coal Measures and represent fish between 60 and 300 mm long. The basihyal tooth plates of Conchopoma are the first record of this genus in the Pennsylvanian of Europe. Lanarkodus clarki has a heterodont dentition not previously described from the Pennsylvanian. All the new material is preserved in thin, laminated shales, suggesting a small lake environment rather than the typical coal swamp. These new discoveries demonstrate that Pennsylvanian lungfish were more diverse than previously realised and add to growing evidence that the rate of lungfish evolution did not decline significantly after the Devonian, and remained high throughout the Carboniferous. Thematic collection: This article is part of the The Palaeontology of Scotland collection available at: https://www.lyellcollection.org/topic/collections/palaeontology-of-scotland