title: A new mid-Silurian aquatic scorpion-one step closer to land?
abstract: One of the oldest known fossil scorpions, a new species from the mid-Silurian Eramosa Formation (430 myr) of Ontario, Canada, exhibits several surprising features. The depositional environment and associated biota indicate a marine habitat; however, the leg morphology of this scorpion, which has a short tarsus in common with all Recent scorpions, suggests that a key adaptation for terrestrial locomotion, the ability to support its weight on a subterminal 'foot', appeared remarkably early in the scorpion fossil record. Specimens are preserved intact and undisturbed in a splayed posture typical of moults rather than carcasses. We postulate that these animals were aquatic, but occasionally ventured into extremely shallow water, or onto a transient subaerially exposed surface while moulting, before returning to deeper water. Shed exuviae were preserved in situ by rapid overgrowth of bacterial biofilm.
authors.affiliation: Department of Natural History (Palaeobiology), Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6 jbwaddington@rogers.com.
authors.forename: Janet
authors.initials: J
authors.lastname: Waddington
authors.affiliation: Department of Natural History (Palaeobiology), Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6.
authors.forename: David M
authors.identifier: http://orcid.org/0000-0003-4727-9312
authors.initials: DM
authors.lastname: Rudkin
authors.affiliation: Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, Berlin 10115, Germany.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Dunlop
mesh_terms: D000818:Animals; D017753:Ecosystem; D005121:Extremities / Q000033:anatomy & histology; D005580:Fossils; D008124:Locomotion; D009864:Ontario; D012605:Scorpions / Q000033:anatomy & histology* / Q000145:classification
keywords: Silurian; behaviour; exuviae; locomotion; new species; scorpion