Jeanerpeton mazonensis , gen. et sp. nov.: a new, exceptionally preserved, late Carboniferous amphibamiform from the Mazon Creek Lagerstätte, Illinois

The Mazon Creek fossil assemblage has provided the earliest fossil records of several important early tetrapod lineages, including the oldest dissorophoid temnospondyl, Amphibamus grandiceps. Recent systematic efforts have unveiled exceptional diversity of recumbirostran tetrapods at Mazon Creek; however, similar attention has not been paid to the numerous temnospondyl fossils from the site. Here, we provide an anatomical and systematic revision to a uniquely preserved amphibamiform from Mazon Creek, FMNH PR 558, that was previously reported to have the earliest body fossil evidence of lissamphibian-like toe pads in temnospondyls. Restudy of this fossil, with particular attention devoted to the dorsal and lateral skull and the axial skeleton has revealed distinct differences from coeval and other Permo-Carboniferous amphibamiforms, allowing for the designation of the new taxon Jeanerpeton mazonensis, gen. et sp. nov. Based on preliminary observations of varying presacral vertebral counts among Mazon Creek amphibamiform fossils there is more diversity of this group from the Moscovian amongst known material than previously recognized.