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Thylacocaris schrami Audo and Charbonnier nov. gen, nov. sp. from the Cenomanian of Hadjoula, Lebanon. A-D. Holotype MNHN.F. A57240, left lateral view, cross-polarized light (A), line-drawing of carapace, and soft-parts (B), carapace and fragments of anterior prehensile appendages, green-orange fluorescence desaturated (C), close-up of optical notch showing broken rostrum and two optical spines, green-orange fluorescence desaturated (D). E-F. Paratype MSNM i24785, carapace, right lateral view, natural light (E), UV light (F). Abbreviations: avp = antero-ventral process, dc = dorsal carina, dm = dorsal margin, ms = muscle scar, on = optical notch, os = optical spine, pn = posterior notch, pu = punctuation, rap = prominent anterior appendages, tl = paddle-like limbs or trunk limbs, ts = trunk somites, vm = ventral margin. Scale bars: 5 mm (A-C, E, F) and 2 mm (D). Line drawing: S. Charbonnier. Photographs: D. Audo (A), J. Haug (C, D) and L. Cazes (E-F).
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Thylacocephalans (Euarthropoda, Thylacocephala) are characterized by their "bivalved" carapace and three anterior prehensile appendages. It is still not clear how they used to live, or what their evolutionary history is. This study focuses on new thylacocephalans from the Late Cretaceous Konservat-Lagerstätten of Lebanon, which yielded the youngest...
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Citations
... Another structure found on the shield of thylacocephalans might be interpreted as a muscle scar. A large rounded protuberance, located on the central area of the shield has been described as muscle scar on multiple species of thylacocephalan species (Ligulacaris parisiana [see Charbonnier et al. 2019]; Dollocaris ingens [see Secrétan & Riou 1983]; Paraostenia voultensis [see Secrétan 1985]; Victoriacaris muhiensis [see Hegna et al. 2014]; Paradollocaris vannieri, Globulocaris garassinoi, Keelicaris deborae [see Charbonnier et al. 2017]; Mayrocaris bucculata [see Laville et al. 2021a]). However, no muscles are found associated with these protuberances, making unlikely that they are muscle scars. ...
Thylacocephalans are enigmatic euarthropods, known at least from the Silurian to the Cretaceous. Despite remaining uncertainties concerning their anatomy, key features can be recognised such as a shield enveloping most of the body, hypertrophied compound eyes, three pairs of raptorial appendages and a posterior trunk consisting of eight up to 22 segments bearing appendages and eight pairs of gills. Well-known for its euarthropod diversity, the La Voulte-sur-Rhône Lagerstätte (Callovian, Middle Jurassic, France) has provided many remains of four thylacocephalan species so far: Dollocaris ingens, Kilianicaris lerichei, Paraostenia voultensis and Clausocaris ribeti. In this paper, we study the type material as well as undescribed material. The re-description of La Voulte thylacocephalans reveals an unexpected diversity, with the description of two new species, Austriocaris secretanae sp. nov. and Paraclausocaris harpa gen. et sp. nov., and of specimens of Mayrocaris, a taxon originally described from Solnhofen Lagerstätten. We also reassign Clausocaris ribeti to Ostenocaris. The reappraisal of La Voulte thylacocephalans also provides important insight into the palaeobiology of Thylacocephala. New key anatomical features are described, such as an oval structure or a putative statocyst, which indicate a nektonic or nektobenthic lifestyle. Finally, we document a juvenile stage for Paraostenia voultensis.
... Known from at least the Silurian (Haug et al., 2014) up to the Late Cretaceous (e.g., Schram et al., 1999;Lange et al., 2001;Charbonnier et al., 2017), thylacocephalans were relatively diverse in the Devonian (Table 1). Fourteen species have been formally described from 10 different localities corresponding to a wide variety of depositional environments, from tidal channels to offshore environments. ...
... In many thylacocephalan species, a thickening of all free margins, or at least of the ventral margin, has been reported. A range of terminology has been used to describe such structure: flanges (Briggs and Rolfe, 1983), marginal carina (Arduini et al., 1980;Schram et al., 1999;Charbonnier et al., 2017), marginal belt (Charbonnier et al., 2019), marginal rim (Ji et al., 2017(Ji et al., , 2021, or mar-FIGURE 9. Appendages of Concavicaris woodfordi (Cooper, 1932). A, longitudinal section (3D rendering). ...
... In many species, large rounded spots located in the anterior or central part of the shield have been described as putative muscle scars. (Secrétan and Riou, 1983;Pinna et al., 1985;Secrétan, 1985;Charbonnier et al., 2017Charbonnier et al., , 2019Laville et al., 2021a). Moreover, those muscle scars can be associated with muscles, as for Ostenocaris cypriformis Arduini, Pinna and Teruzzi, 1980 from the Early Jurassic of Italy (Arduini et al., 1980;Pinna et al., 1985). ...
Known from at least the Silurian to the Cretaceous, Thylacocephala is an enigmatic fossil euarthropod ingroup, often allied with Pancrustacea. Previous studies show that thylacocephalans are characterized by a folded protective shield, hypertrophied compound eyes, three pairs of raptorial appendages, a posterior trunk comprised of eight to 22 segments bearing appendages, and eight pairs of gills. Despite this knowledge of their anatomy, many questions remain, especially surrounding the anatomy of Paleozoic representatives.
The Upper Devonian Woodford Shale (upper Famennian, Oklahoma, USA) has yielded several fossil euarthropods, including two species of Thylacocephala: Concavicaris elytroides and Concavicaris woodfordi. Here, we use micro-computed X-ray tomography to re-explore the anatomy of the holotype of C. woodfordi, illustrating fine details of the shield structure, of the circulatory, digestive and reproductive systems, and of the appendages. A marginal fold of the shield as well as an inner layer are described for the first time in a thylacocephalan. Concavicaris woodfordi shares similarities with Concavicaris submarinus, another Famennian species, including the morphology of the shield and the internal anatomy. It also displays a similar organisation as Mesozoic taxa, such as Dollocaris ingens. All of this provides important information that will be crucial to reconstruct the evolution and the affinities of Thylacocephala.
... Questions also remain about their lifestyles. Various modes of life were proposed for representatives of Thylacocephala: endobenthic (Pinna et al. 1985), pelagic (Schram et al. 1999;Charbonnier et al. 2017) or nektobenthic (Rolfe 1985;Vannier et al. 2016). Concerning their diets, thylacocephalans are often interpreted as predators based on the combination of raptorial appendages, large forwardly directed eyes and preserved gut contents (Vannier et al. 2016). ...
... Haug et al. 2014). They probably became extinct in the Late Cretaceous, when they last occur (Schram et al. 1999;Lange et al. 2001;Charbonnier et al. 2017). Thylacocephalans are known from China (Shen 1983;Feldmann et al. 2015;Ji et al. 2017Ji et al. , 2021, Japan (Ehiro et al. 2015(Ehiro et al. , 2019, Australia (Briggs & Rolfe 1983;Haig et al. 2015), Lebanon (Schram et al. 1999;Lange et al. 2001;Charbonnier et al. 2017), Madagascar (Arduini 1990), Morocco (Jobbins et al. 2020), Austria (Glaessner 1931), Czech Republic (Chlup a c 1963;Rak et al. 2018;Broda et al. 2020), France (Van Straelen 1923;Secr etan & Riou 1983;Secr etan 1985;Charbonnier et al. 2010), Germany (Polz 1990(Polz , 1994(Polz , 2001Braig et al. 2019), Italy (Pinna 1974(Pinna , 1976Arduini et al. 1980;Arduini & Brasca 1984;Pinna et al. 1982Pinna et al. , 1985Dalla Vecchia & Muscio 1990;Arduini 1992;Dalla Vecchia 1993;Teruzzi & Muscio 2019), Poland (Broda et al. 2015, Scotland (Van Der Brugghen et al. 1997), Slovenia (Kri znar & Hitij 2010), Spain (Calzada & Mañ e 1993), Mexico (Hegna et al. 2014) and the USA (e.g . ...
... They probably became extinct in the Late Cretaceous, when they last occur (Schram et al. 1999;Lange et al. 2001;Charbonnier et al. 2017). Thylacocephalans are known from China (Shen 1983;Feldmann et al. 2015;Ji et al. 2017Ji et al. , 2021, Japan (Ehiro et al. 2015(Ehiro et al. , 2019, Australia (Briggs & Rolfe 1983;Haig et al. 2015), Lebanon (Schram et al. 1999;Lange et al. 2001;Charbonnier et al. 2017), Madagascar (Arduini 1990), Morocco (Jobbins et al. 2020), Austria (Glaessner 1931), Czech Republic (Chlup a c 1963;Rak et al. 2018;Broda et al. 2020), France (Van Straelen 1923;Secr etan & Riou 1983;Secr etan 1985;Charbonnier et al. 2010), Germany (Polz 1990(Polz , 1994(Polz , 2001Braig et al. 2019), Italy (Pinna 1974(Pinna , 1976Arduini et al. 1980;Arduini & Brasca 1984;Pinna et al. 1982Pinna et al. , 1985Dalla Vecchia & Muscio 1990;Arduini 1992;Dalla Vecchia 1993;Teruzzi & Muscio 2019), Poland (Broda et al. 2015, Scotland (Van Der Brugghen et al. 1997), Slovenia (Kri znar & Hitij 2010), Spain (Calzada & Mañ e 1993), Mexico (Hegna et al. 2014) and the USA (e.g . Schram 1990;C. ...
Known from at least the Silurian (c. 435 Ma) up to the Late Cretaceous (c. 85 Ma), thylacocephalans are among the most intriguing fossil euarthropods. They are characterized by a prominent shield enveloping most of the body, hypertrophied compound eyes, three pairs of large, raptorial appendages and a trunk with 8–22 stout segments bearing appendages. Despite this knowledge of their anatomy, the phylogenetic affinities of Thylacocephala are controversial due to a lack of knowledge on their body organization and tagmosis. This study focuses on Mayrocaris bucculata Polz, 1994 Polz, H. 1994. Mayrocaris bucculata gen. nov. sp. nov. (Thylacocephala, Conchyliocarida) aus den Solnhofener Plattenkalken. Archaeopteryx, 12, 35–44. [Google Scholar] from the Solnhofen Lagerstätte, Germany (c. 150 Ma, early Tithonian, Jurassic). We document new specimens of Mayrocaris bucculata from the Solnhofener Plattenkalke sensu lato and provide new descriptions for previously reported specimens. We demonstrate that the raptorial appendages of Thylacocephala are most probably maxillulae, maxillae and maxillipeds. Additionally, we report new details on the posterior trunk appendages, including the description of a paddle-like proximal part and of a rod-like distal part, but also of a specialized terminal trunk appendage. These new findings, in addition to the reinterpretation of a cephalic appendage of Clausocaris lithographica as a possible mandible, are essential for a better understanding of the body organization in thylacocephalans and their phylogenetic affinities within Eucrustacea.
... Indeed, for the Cenomanian localities, the sub-lithographic limestones yield varied and exquisitely preserved fossils including vertebrates (fish, reptiles), invertebrates (arthropods, annelids, cephalopods, echinoderms) and terrestrial plants. Amongst the arthropods, malacostracans are the most common fossils and they were the subject of several studies (Brocchi, 1875;Fraas, 1878;Dames, 1886;Glaessner, 1945;Roger, 1946;Förster, 1984;Garassino, 1994Garassino, , 2001Larghi, 2004;Garassino and Schweigert, 2006;Schram et al., 1999;Charbonnier, 2012, 2013;Petit and Charbonnier, 2012;Charbonnier et al., 2017aCharbonnier et al., , 2017bGarassino and Pasini, 2020;Pasini et al., 2020). ...
A large sample of mecochirid lobsters (Crustacea, Decapoda, Mecochiridae) has been recently collected from the early Barremian (Early Cretaceous) of Lebanon. The studied specimens are described as Meyeria libanotica sp. nov. The genus Meyeria M’Coy, 1849 is also revised and new combinations are proposed for two species: Meyeria bartholomaii (Jell, Woods, and Cook, 2017) comb. nov. (Aptian, Australia), and Meyeria rostrata (Collins and Rasmussen, 1992) comb. nov. (Campanian–Maastrichtian, Greenland). The stratigraphic range and the palaeogeographic distribution of Meyeria are consequently recognized to spread from the Oxfordian (Late Jurassic) to the Maastrichtian (Late Cretaceous) and from Australia to Greenland, passing by Europe, respectively.
... Thylacocephala has a long stratigraphic record and was especially highly diversified in the Mesozoic. Their fossil record dates back to the Silurian (Haug et al., 2014) and possibly even earlier to the Cambrian (Vannier et al., 2006), and extends to as recently as the Late Cretaceous (Dames, 1886;Schram et al., 1999;Charbonnier et al., 2017). Multiple localities have been reported with records spanning from Europe, Central and East Asia, Madagascar, and Australia (see Schram, 2014 andBraig et al., 2019 for a review). ...
... Charbonnier et al. (2017, p. 5) pointed out the feeble bases of Schram's subdivision but kept using it without redefining this family. Moreover, Charbonnier et al. (2017) made the situation more confusing at least for a few genera/ (2014) already pointed out that Thylacocephalus was assigned to Microcaridida only on the basis of a similar, but not identical, ornamentation while its body outline is very different from other Triassic genera, especially in the presence of a long posterior spine rather than the anterior rostrum. Following Charbonnier et al. (2017, p. 12), we exclude Thylacocephalus from this family because of its unique ornamentation (the presence of posterior and ocular spines and several vertical rows of pits) and carapace outline. ...
Here we report and describe a new assemblage of Thylacocephala (Crustacea) from the late Spathian (Early Triassic) of Chaohu, Anhui Province, South China. The assemblage consists of at least three species from different genera: the small-sized Microcaris rectilineatus n. sp. appears the most abundant, while the large-sized Ankitokazocaris sp. and Diplacanthocaris chaohuensis n. gen. n. sp. are rare. A morphometric analysis of the carapace outline separates Diplacanthocaris chaohuensis n. gen. n. sp. from other genera. Along with Ankitokazocaris chaohuensis Ji et al., 2017 and Kitakamicaris sp. from the horizon 28 m above this assemblage, four different genera of Thylacocephala occur in the Chaohu Fauna. With additional materials reported from Japan and North America, the Early Triassic is now known as the period when Thylacocephala reached their highest diversity and widest geographical distribution. Thylacocephala quickly diversified shortly after the Permian–Triassic mass extinction, probably because of their ability to survive in a relatively low-oxygen environment. Thylacocephalan fossils from Chaohu are found in dense concentrations, suggesting they might have constituted a food source for the fishes and marine reptiles in the Chaohu Fauna.
UUID: http://zoobank.org/b24e82a7-ea9a-49dc-9c6c-8ad8262db276
... Par rapport à la fluorescence UV, la fluorescence orange présente l'avantage de ne pas être sensible aux fréquentes poussières de papier ou de textiles blancs. De nombreux fossiles présentent une autofluorescence sous une lumière verte, c'est notamment le cas des crustacés issus des calcaires lithographiques du Jurassique d'Italie, d'Allemagne, de France et du Crétacé du Liban (Haug et al. 2016 ;Charbonnier et al. 2017b). ...
Le MNHN est l’un des piliers de la recherche sur les crustacés fossiles qui s’appuie sur une collection de plus de 20 000 échantillons. Cette collection a été constituée par les pionniers de la paléontologie des invertébrés marins et de la micropaléontologie. Elle a servi de base à l’établissement de la systématique des crustacés et de leur histoire évolutive. Cette collection est aujourd’hui valorisée par l’utilisation de nouvelles technologies qui permettent de répondre à des questionnements sur les relations de parenté entre les crustacés fossiles et actuels, sur leur origine et leur diversification, sur leur distribution géographique et l’occupation des niches écologiques au cours des temps géologiques. Lumière ultra-violette, lumière verte, radiographie aux rayons X, microtomographie à rayons X ct-scan, imagerie par fluorescence des rayons X synchrotron sont autant de techniques qui révèlent la préservation de détails anatomiques invisibles à l’œil nu, des organes internes, des dispositifs visuels, des stades larvaires. Le microscope électronique à balayage documente, à partir de prélèvements anciens, des formes inédites de microcrustacés et permet ensuite de révéler de nouvelles relations paléobiogéographiques. Les nouvelles technologies valorisent ainsi la collection de crustacés fossiles qui ne cesse de s’enrichir.
... Their first undisputed appearance in the fossil record dates back to the Silurian 1 , although some fossils of Early Cambrian age 2 may also belong to this group. Thylacocephalans lived until the Late Cretaceous period; the youngest fossils were found in the Cenomanian of Lebanon [3][4][5] . ...
Thylacocephalans are enigmatic arthropods with an erratic Palaeozoic and Mesozoic fossil record. In many of the few localities where they occur, they are quite abundant. This also holds true for the Famennian Thylacocephalan Layer in the Maider (eastern Anti-Atlas of Morocco), a small epicontinental basin hosting some strata with taphonomic properties of a conservation deposit yielding exceptionally preserved gnathostomes and non-vertebrates. In a thin argillaceous interval in the earliest middle Famennian, thylacocephalans occur in such great numbers that they became eponyms of this unit. Therein, we discovered a new taxon of thylacocephalans, Concavicaris submarinus sp. nov., which represent the oldest records of thylacocephalans from Africa. In the CT-imagery, the holotype of Concavicaris submarinus sp. nov. revealed anatomical details including its eyes, appendages and other soft parts. Sedimentary facies and faunal composition of the Thylacocephalan Layer suggest that these animals populated the water column above the low-oxygen sea floor. Thus, thylacocephalans likely represented an important component of the diet of chondrichthyans and placoderms, which are quite common as well. The abundance of thylacocephalans in other conservation deposits like the Cleveland Shale (USA) and the Gogo Formation (Australia) underline their pivotal role in Late Devonian pelagic food webs.
... Fossil arthropods from these Konservat-Lagerstätten are all preserved flattened on sublithographic limestones. Despite this compaction, three-dimensional aspects are occasionally preserved (Charbonnier et al. 2017a) in addition to fine structures such as ommatidia and setae (Charbonnier et al. 2017b). However, the cuticle is commonly subject to microfracturing and recrystallization of the fossil occurs infrequently. ...
... Fossil arthropods from these Konservat-Lagerstätten are all preserved flattened on sublithographic limestones. Despite this compaction, three-dimensional aspects are occasionally preserved (Charbonnier et al. 2017a) in addition to fine structures such as ommatidia and setae (Charbonnier et al. 2017b). However, the cuticle is commonly subject to microfracturing and recrystallization of the fossil occurs infrequently. ...
... The origins of this exceptional preservation relate to the very pure, extremely fine-grained limestone, consisting of ca. 1 μm wide (Barthel et al. 1990;Briggs and Wilby 1996;Briggs et al. 2005), Cerin (Briggs 2003;Bernier et al. 2014), and Canjuers (Peyer et al. 2014)-in which each bed is capped with millimetre to centimetre thick laminates, consisting of smooth and continuous calcite layers that preserve the fossils. Extensive excavation of these Konservat-Lagerstätten (Charbonnier et al. 2017b) yielded marine invertebrates (ammonites, bivalves, gastropods, echinoderms, polychaetes, decapod and isopod crustaceans, thylacocephalans, xiphosurids), and vertebrates (fish, pterosaurs, snakes, turtles, varanoids, and birds) (Dalla Vecchia et al. 2001;Wippich and Lehmann 2004;Tong et al. 2006;Audo and Charbonnier 2012a;Charbonnier et al. 2017b). Among these fossils, xiphosurids represent a small part of the assemblage. ...
Xiphosurida—crown group horseshoe crabs—are a group of morphologically conservative marine chelicerates (at least since the Jurassic). They represent an idealised example of evolutionary stasis. Unfortunately, body fossils of horseshoe crabs seldom preserve appendages and their associated features; thus, an important aspect of their morphology is absent in explorations of their conservative Bauplan. As such, fossil horseshoe crab appendages are rarely considered within a comparative framework: previous comparisons have focussed almost exclusively on extant taxa to the exclusion of extinct taxa. Here, we examine eight specimens of the xiphosurid Tachypleus syriacus (Woodward, 1879) from the Cenomanian (ca 100 Ma) Konservat-Lagerstätten of Lebanon, five of which preserve the cephalothoracic and thoracetronic appendages in exceptional detail. Comparing these appendages of T. syriacus with other fossil xiphosurids highlights the conserved nature of appendage construction across Xiphosurida, including examples of Austrolimulidae, Paleolimulidae, and Limulidae. Conversely, Belinuridae have more elongate cephalothoracic appendages relative to body length. Differences in appendage sizes are likely related to the freshwater and possible subaerial life modes of belinurids, contrasting with the primarily marine habits of other families. The morphological similarity of T. syriacus to extant members of the genus indicates that the conserved nature of the generic lineage can be extended to ecological adaptations, notably burrowing, swimming, possible diet, and sexual dimorphism.
... Thylacocephalans are among the most intriguing euarthropods of the Palaeozoic and Mesozoic. They have a stratigraphic range extension from the Silurian ( Haug et al., 2014) and possibly earlier (Cambrian;Vannier et al., 2006) to the Late Cretaceous (Dames, 1886;Schram et al., 1999;Charbonnier et al., 2017), when they probably became extinct. They also show a high palaeobiogeographic distribution and are known from all continents except Antarctica and South America ( Hegna et al., 2014). ...
... The specimens were therefore documented under macro-fluorescence setting to enhance the contrast between the fossil and its surrounding matrix. UV fluorescence is obtained by illuminating the fossil with a ''dark-light'' (blue to UV light) under which numerous fossil euarthropods, especially from limestone, display a strong yellow autofluorescence (e.g., Haug et al., 2009;Charbonnier et al., 2017). Pictures are digitally white-balanced to facilitate the visualisation of fluorescence. ...
... However, Ehiro et al. (2015) considered that no clear definition was given to these families and it seems that further examination is necessary for family-level classification. Even if it is probably perfectible, and according to Charbonnier et al. (2017), we follow here the classification (''working hypothesis'') proposed by Schram (2014 Brasca, 1984;Ferrecaris Calzada et Mañ e ´ , 1993;Microcaris Pinna, 1974;Kitakamicaris Ehiro et Kato in Ehiro et al., 2015; Parisicaris nov. gen. ...
... Thylacocephalans are among the most intriguing euarthropods of the Palaeozoic and Mesozoic. They have a stratigraphic range extension from the Silurian (Haug et al., 2014) and possibly earlier (Cambrian; Vannier et al., 2006) to the Late Cretaceous (Dames, 1886;Schram et al., 1999;Charbonnier et al., 2017), when they probably became extinct. They also show a high palaeobiogeographic distribution and are known from all continents except Antarctica and South America (Hegna et al., 2014). ...
... The specimens were therefore documented under macro-fluorescence setting to enhance the contrast between the fossil and its surrounding matrix. UV fluorescence is obtained by illuminating the fossil with a ''dark-light'' (blue to UV light) under which numerous fossil euarthropods, especially from limestone, display a strong yellow autofluorescence (e.g., Haug et al., 2009;Charbonnier et al., 2017). Pictures are digitally white-balanced to facilitate the visualisation of fluorescence. ...
... However, Ehiro et al. (2015) considered that no clear definition was given to these families and it seems that further examination is necessary for family-level classification. Even if it is probably perfectible, and according to Charbonnier et al. (2017), we follow here the classification (''working hypothesis'') proposed by Schram (2014 Genus Parisicaris Charbonnier nov. gen. ...
Two new genera and species of thylacocephalans (Arthropoda, Thylacocephala), Parisicaris triassica Charbonnier and Ligulacaris parisiana Charbonnier, are described from the early Spathian Paris Biota. These new occurrences are the first reports of thylacocephalans from Triassic rocks in North America. They considerably enlarge the spatiotemporal distribution of these enigmatic arthropods and highlight their relatively high generic richness during the Early Triassic. It also confirms that the Triassic was the taxonomically richest period for Thylacocephala.
