The Carboniferous (Pennsylvanian; 309-307 Mya) 'Mazon Creek' Lagerstätte produces some of the earliest tetrapod fossils of major Palaeozoic lineages. Previously, the Mazon Creek record of lysorophians was known from a single poorly preserved specimen consisting only of a partial vertebral column. Here we describe a new, virtually complete lysorophian genus and species, Infernovenator steenae gen. & sp. nov. on the basis of a unique combination of characters, including a near complete circumorbital series and the retention of a postfrontal. Parsimony-based phylogenetic analysis placed the new taxon in the family Molgophidae, as sister to Brachydectes newberryi. Those results and the more generalized cranial morphology present in Infernovenator further support a recumbirostran origin of Molgophidae. Co-occurrence of two morphologically and functionally distinct molgophids in the Early Moscovian suggests a rapid and underappreciated diversification of this family in the Early Pennsylvanian.

Carboniferous, fossil, Microsauria, Molgophidae, Pennsylvanian, Recumbirostra
Zoological Journal of the Linnean Society
Department of Earth Sciences

Mann, A. (Arjan), Pardo, J.D. (Jason D.), & Maddin, H. (2019). Infernovenator steenae, a new serpentine recumbirostran from the 'Mazon Creek' Lagerstätte further clarifies lysorophian origins. Zoological Journal of the Linnean Society, 187(2), 506–517. doi:10.1093/zoolinnean/zlz026