Morphology of the Late Carboniferous temnospondyl Limnogyrinus elegans, and the evolutionary history of the Micromelerpetidae

摘要

The Pennsylvanian tetrapod Limnogyrinus elegans from the gas coal of Nyrany (Czech Republic) is revised. This small dissorophoid temnospondyl bears closer resemblance to the Permian genus Branchierpeton than hitherto known, highlighted by the abbreviated postparietal and tabular and the shallow squamosal embayment. It has a wide open squamosal embayment, with a posterolaterally much widening skull table, quadrate condyles well anterior to occipital ones, a lacrimal overplating the prefrontal with a substantial medial process, and a tabular that is dorsally overplapped by the supratemporal. Contrasting former suggestions, phylogenetic analysis finds Limnogyrinus to nest well within a monophyletic family Micromelerpetidae, with Nyranerpeton and Branchierpeton as successive sister taxa, whereas the relatively long-skulled Micromelerpeton and Eimerisaurus form the base of this Clade.