The impact of taphonomic data on phylogenetic resolution: Helenodora inopinata (Carboniferous Mazon Creek Lagerstätte) and the onychophoran stem lineage

摘要

BackgroundThe origin of the body plan of modern velvet worms (Onychophora) lies in the extinct lobopodians of the Palaeozoic. Helenodora inopinata, from the Mazon Creek Lagerstätte of Illinois (Francis Creek Shale, Carbondale Formation, Middle Pennsylvanian), has been proposed as an intermediate between the “weird wonders” of the Cambrian seas and modern terrestrial predatory onychophorans. The type material of H. inopinata, however, leaves much of the crucial anatomy unknown.