A review of Silvanerpeton miripedes, a stem amniote from the Lower Carboniferous of East Kirkton, West Lothian, Scotland

Abstract

Previously described and new specimens of the anthracosaur Silvanerpeton miripedes from the Scottish Viséan of East Kirkton yield important new data which allow us to provide a more complete reconstruction of the skull roof, palate, braincase and lower jaw. A stout sacral rib and an incompletely ossified tarsus with a subquadrangular intermedium are also recorded for the first time. A remarkably well preserved humerus in extensor view shows similarities with humeri of immature specimens of the embolomere Proterogyrinus. A new cladistic analysis, built from combining characters used in two recent matrices, places Silvanerpeton in a basal position relative to embolomeres and more derived stem amniotes. Data from Silvanerpeton inform character polarity near the base of the amniote total group. We discuss some morphofunctional implications of character changes at the root of total group amniotes, acquisition of terrestrial habits, and patterns of early disparity in this clade.