Oldest North American orthostern scorpion from the Carboniferous (Pennsylvanian: Bashkirian) Pottsville Formation of Alabama, USA

Scorpions are an ancient chelicerate group with a fossil record extending back to the Silurian and a peak in reported fossil forms during the Carboniferous. Most Carboniferous scorpions are from Coal Measures sites, a small number of which exceptionally preserve evidence of respiratory structures. To expand the record of such material, we present a new fossil scorpion specimen from the Pennsylvanian (Bashkirian) Pottsville Formation from the Union Chapel Mine, Alabama, USA. We demonstrate that UV imagery is a useful tool for examining fossil scorpions, as it can clearly illustrate exoskeletal sections, and other important morphological structures. This specimen shows probable intrasternal spiracles, illustrating this is one of the oldest members of the derived scorpion infraorder Orthosterni, and potentially preserves evidence of book lungs. Due to the lack of taxonomically important features, such as coxosternal morphologies, we cannot identify the specimen beyond Orthosterni. We used Energy Dispersive X-Ray Spectroscopy (EDS) to explore fossil preservation, determining the specimen is preserved almost entirely as carbon, indicating it had undergone kerogenisation. This body fossil complements walking trace fossils from the same site attributed to scorpions, represents the first fossil scorpion from the southeastern USA, and provides more evidence for extensive diagenetic alteration of cuticle in fossil scorpions from Coal Measures.