Erpetonyx arsenaultorum is an extinct genus of bolosaurian parareptile from the uppermost or Gzhelian stage of the Carboniferous rocks. It is known from a single, articulated and mostly complete specimen from Cape Egmont, in southwestern Prince Edward Island, Canada Prince County, in the Edgmont Bay Formation that preserves fossils in the stratigraphic layer that dates back to the Carboniferous period. It is the earliest known parareptile, and brings back the origins of several clades into the Carboniferous.