James St. John: Diplocraterion trace fossil (Arnheim Formation, Upper Ordovician; Hamilton County, southwestern Ohio, USA)
James St. John: Diplocraterion trace fossil (Kope Formation, Upper Ordovician; Rt. 9 roadcut near Alexandria, Kentucky, USA)
James St. John: Diplocraterion trace fossils in limestone (Fairview Formation, Upper Ordovician; Maysville West roadcut, Kentucky, USA) 1
James St. John: Diplocraterion trace fossil in limestone (Fairview Formation, Upper Ordovician; Maysville West roadcut, Kentucky, USA) 2
James St. John: Diplocraterion trace fossils in limestone (Fairview Formation, Upper Ordovician; Maysville West roadcut, Kentucky, USA) 3
James St. John: Diplocraterion trace fossil (Kope Formation, Upper Ordovician; Maysville West roadcut, Mason County, Kentucky, USA) 1
James St. John: Diplocraterion trace fossil (Kope Formation, Upper Ordovician; Maysville West roadcut, Mason County, Kentucky, USA) 2