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.
Highlights
The process of fossilisation offers only a partial insight into past environments: the morphological features of organisms are preserved, but their biotic interactions and their surrounding palaeoenvironments are rarely directly observable, except in a few specific cases
We expand on the palaeoecology and bathymetry of the La Voulte biota based on the exceptional preservation of eyes bearing ommatidia in the polychelidan lobster Voulteryon parvulus Audo et al 2014, and a unique colonization by minute brachiopods: an unusual case of association between brachiopods and a motile host[11,12]
The ocular incisions of Voulteryon parvulus are excavated on short expansions of the carapace reminiscent of the disposition of the eyes in Eryon Desmarest, 1817, and surround most of the ocular peduncle
Summary
The process of fossilisation offers only a partial insight into past environments: the morphological features of organisms are preserved, but their biotic interactions and their surrounding palaeoenvironments are rarely directly observable, except in a few specific cases. An example is the polychelidan lobsters; a group of decapod crustaceans characterized by having four to five pairs of claws From their first occurrence in the Triassic to Jurassic, they had well-developed eyes and occurred in various environments and depths[1], while the few extant species all have reduced eyes and live in deep waters worldwide[2,3]. We expand on the palaeoecology and bathymetry of the La Voulte biota based on the exceptional preservation of eyes bearing ommatidia in the polychelidan lobster Voulteryon parvulus Audo et al 2014, and a unique colonization by minute brachiopods: an unusual case of association between brachiopods and a motile host[11,12] This association has no direct modern counterpart, and it might be linked to the higher brachiopod diversity in the Callovian than nowadays
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