High biodiversity in Polychelida crustaceans from the Jurassic La Voulte-sur-Rhône Lagerstätte

Konservat-Lagerst€ atten are seen as snapshots of past biodiversity for a given location and time. However, processes leading to the exceptional morphological preservation of fossils in these deposits remain incompletely understood. This results in a deficient assessment of taphonomic biases and limits the robustness/relevance of palaeobiological reconstructions. Here, we report the mineralogical characterization of crustacean fossils preserved within carbonate-rich concretions from the Jurassic Konservat-Lagerst€ atte of La Voulte-sur-Rhône (Ard eche, France). The combination of SEM-EDS, TEM, synchrotron-based XRF, XRD and XANES allows the mineralogical phases composing these fossils (i.e. fluorapatite, Fe-sulfides (pyrite, pyrrhotite) and Mg-calcite) and the surrounding matrix (i.e. Mg-calcite, clays and detrital silicates) to be identified. Fluorapatite and pyrite (and pyrrhotite) precipitated during decay under anoxic conditions, replacing delicate organic structures and preserving anatomical details. These mineral structures were subsequently consolidated by a Mg-calcite cement. Of note, histologically similar tissues were replaced by the same mineral phases, confirming that fossilization (in La Voulte) occurred rapidly enough to be influenced by tissue composition. Altogether, the present study shows that exceptional preservation requires fast biodegradation, thereby confirming recent experimental evidence.

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“…, ; Charbonnier ; Audo et al . , b, , ; Jauvion et al . , ; Audo & Schweigert ) and cephalopods (Fischer & Riou , ; Fischer ; Kruta et al .…”

unclassified

Exceptional preservation requires fast biodegradation: thylacocephalan specimens from La Voulte‐sur‐Rhône (Callovian, Jurassic, France)

et al. 2019

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“…Therefore, it seems unlikely that R. oppeli was well adapted to float in the water column. Besides, the structure of the pereiopods in R. oppeli is more consistent with benthic life-habits: indeed, its pereiopods seem more massive than those of Knebelia bilobata¸ Willemoesiocaris ovalis (Van Straelen, 1923) (Audo et al 2014c) and even that of extant Polychelidae. Considering the relatively small uropods and massive pereiopods, a thin carapace does not seem sufficient to propose a swimming life-habit for Rogeryon oppeli.…”

Section: Relation To Substratementioning

confidence: 89%

“…Contrary to polychelidans which might have been more nektobenthic such as Willemoesiocaris ovalis (Van Straelen, 1923) (Audo et al 2014c) or well-adapted to swim (Audo et al 2014b), Rosenfeldia triasica seems to possess a rather thick carapace and stout pereiopods. It was therefore undoubtedly mostly benthic.…”

Section: Palaeobiology Of Rosenfeldia Triasicamentioning

confidence: 99%

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Systematic revision and palaeobiology of Rosenfeldia triasica and Rogeryon oppeli gen. et comb. nov. (Eucrustacea, Polychelida)

Audo

Schweigert

Charbonnier

et al. 2017

EJT

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475

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Abstract. Polychelidan lobsters (Decapoda: Polychelida) are crustaceans with extant species which are restricted to deep water environments. Fossil species, however, used to live in more varied palaeoenvironments, from shallow water to deep water, and were more diverse morphologically. We redescribe two species of polychelidan lobsters, the Late Triassic Rosenfeldia triasica Garassino, Teruzzi & Dalla Vecchia, 1996 and the Late Jurassic Eryon oppeli Woodward, 1866, recently assigned to the same genus, Rosenfeldia, based upon only a few characters. Our investigation of all available material of both species leads us to distinguish these two species and to erect Rogeryon gen. nov. to accommodate Eryon oppeli. The palaeobiology of both species is interpreted for the first time. Rosenfeldia triasica with its stout first pereiopods and mandibles with both incisor and molar processes (documented for the first time in Polychelida) was benthic and probably fed either on slow-moving sedentary preys or was a scavenger. Rogeryon oppeli gen. et comb. nov. was benthic, visually adapted to shallow water palaeoenvironments, and possibly had a diet similar to that of slipper lobsters and horseshoe crabs. The redescription of these two species highlights the palaeobiological diversity of fossil polychelidans.

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“…Polychelids were most morphologically diverse during Mesozoic (Audo et al, 2014), with fi ve families recognized: Eryonidae De Haan, 1841, Coleiidae Van Straelen, 1924, Tetrachelidae Beurlen, 1930and Polychelidae Wood-Mason, 1874. Th e latter family is the only extant and currently comprises about 38 species distributed in six genera (Ahyong, 2009;De Grave et al, 2009;Chan, 2010).…”

Section: Introductionmentioning

confidence: 99%

Primitive decapods from the deep sea: first record of blind lobsters (Crustacea: Decapoda: Polychelidae) in northeastern Brazil

Ribeiro

2015

Nauplius

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ABSTRACT:We report herein the occurrence of the infraorder Polychelida in Potiguar Basin, northeastern Brazil. Specimens were collected by the project "Avaliação da Biota Bentônica e Planctônica na porção off shore das Bacias Potiguar e Ceará", developed by the Brazilian Oil Company (PETROBRAS). Th ree species were recorded for the fi rst time in this region: Pentacheles validus A. Milne-Edwards, 1880, Polycheles typhlops Heller, 1862, and Stereomastis sculpta (Smith, 1880) at 2000 m, 400 m and 2057 m depth, respectively. Th e Brazilian deep-sea fl oor remains poorly known, but progress has been made as a result of collections obtained by oceanographic expeditions and research projects developed by PETROBRAS in Campos Basin (Rio de Janeiro) and Potiguar Basin (Rio Grande do Norte), expanding the knowledge of the distribution area of Polychelidae in Brazilian deep sea waters.

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High biodiversity in Polychelida crustaceans from the Jurassic La Voulte-sur-Rhône Lagerstätte

Cited by 26 publications

References 32 publications

Exceptional preservation requires fast biodegradation: thylacocephalan specimens from La Voulte‐sur‐Rhône (Callovian, Jurassic, France)

Exceptional preservation requires fast biodegradation: thylacocephalan specimens from La Voulte‐sur‐Rhône (Callovian, Jurassic, France)

Systematic revision and palaeobiology of Rosenfeldia triasica and Rogeryon oppeli gen. et comb. nov. (Eucrustacea, Polychelida)

Primitive decapods from the deep sea: first record of blind lobsters (Crustacea: Decapoda: Polychelidae) in northeastern Brazil

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