Palaeoecology of Voulteryon parvulus (Eucrustacea, Polychelida) from the Middle Jurassic of La Voulte-sur-Rhône Fossil-Lagerstätte (France)

Abstract

Exceptional and extremely rare preservation of soft parts, eyes, or syn-vivo associations provide crucial palaeoecological information on fossil-rich deposits. Here we present exceptionally preserved specimens of the polychelidan lobster Voulteryon parvulus, from the Jurassic of La Voulte-sur-Rhône Fossil-Lagerstätte, France, bearing eyes with hexagonal and square facets, ovaries, and a unique association with epibiont thecideoid brachiopods, giving insights onto the palaeoenvironment of this Lagerstätte. The eyes, mostly covered in hexagonal facets are interpreted as either apposition eyes (poorly adapted to low-light environment) or, less likely, as refractive or parabolic superposition eyes (compatible with dysphotic palaeoenvironments). The interpretation that V. parvulus had apposition eyes suggests an allochthonous, shallow water origin. However, the presence of thecideoid brachiopod ectosymbionts on its carapace, usually associated to dim-light paleoenvironments and/or rock crevices, suggests that V. parvulus lived in a dim-light setting. This would support the less parsimonious interpretation that V. parvulus had superposition eyes. If we accept the hypothesis that V. parvulus had apposition eyes, since the La Voulte palaeoenvironment is considered deep water and had a soft substrate, V. parvulus could have moved into the La Voulte Lagerstätte setting. If this is the case, La Voulte biota would record a combination of multiple palaeoenvironments.