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... France, Germany and Switzerland). Specifically, we extracted data from the lower jaws of Torvoneustes jurensis (MJSN BSY008-465; [34]); Proexochokefalos heberti (MNHN.F 1890-13) Machimosaurus buffetauti (SMNS 91415), Suchodus durobrivensis (unnumbered specimen; see [35]) and Dakosaurus maximus (SMNS 82043). The measurements of the majority of specimens were personally hand measured by D.F. with digital callipers, while the remaining were obtained through literature and corroborated with digital measurements using ImageJ [36]. ...
Mesozoic marine ecosystems were dominated by diverse lineages of aquatic tetrapods. For over 50 Ma in the Jurassic until the Early Cretaceous, plesiosaurians, ichthyosaurians and thalattosuchian crocodylomorphs coexisted at the top levels of trophic food webs. We created a functional dataset of continuous craniomandibular and dental characters known from neontological studies to be functionally significant in modern aquatic tetrapods. We analysed this dataset with multivariate ordination and inferential statistics to assess functional similarities and differences in the marine reptile faunas of two well-sampled Jurassic ecosystems deposited in the same seaway: the Oxford Clay Formation (OCF, Callovian–early Oxfordian, Middle–Late Jurassic) and the Kimmeridge Clay Formation (KCF, Kimmeridgian–Tithonian, Late Jurassic) of the UK. Lower jaw-based macroevolutionary trends are similar to those of tooth-based diversity studies. Closely related species cluster together, with minimal overlaps in the morphospace. Marine reptile lineages were characterized by the distinctive combinations of features, but we reveal multiple instances of morphofunctional convergence among different groups. We quantitatively corroborate previous observations that the ecosystems in the OCF and KCF were markedly distinct in faunal composition and structure. Morphofunctional differentiation may have enabled specialization and was an important factor facilitating the coexistence of diverse marine reptile assemblages in deep time.
... This skeleton is nearly 2.5 m long, with a perfectly intact vertebral column (not sheared, as with many specimens from this area) and has all its gastric contents in place within the rib cage. Having been in a private collection, this specimen was only mentioned in [1] in a limited context for measurements used for its locomotor profile, and was first figured in 2008 as part of a crocodilian exhibition in Normandy (complete skeleton illustrated in [2], Figure 1). This specimen has been housed in Elbeuf, Fabrique des Savoirs (FBS) since 2012, under the accession number 2012. ...
... This specimen was diagnosed as Metriorhynchus cf. superciliosus [1,2]. ...
... The skeleton itself is composed of the left posterior mandibular ramus, nearly thirty complete cervical and thoracic ribs, forty articulated vertebrae from the cervical to caudal areas, the right pectoral girdle, the right humerus, and both sides of the pelvic girdle ( [2]). ...
A new metriorhynchid specimen with stomach contents is described here. Assigned to Metriorhynchus cf. superciliosus., this specimen has a clear longirostrine form as indicated by its gracile and elongated mandibular rami. This is the second example of gastric contents described for Metriorhynchidae. This specimen’s preservation allows the identification of the gill apparatus remains of Leedsichthys, the giant suspension-feeding osteichthyan from the Jurassic, including its gill rakers. The gastric contents also contain remains of invertebrates. This specimen indicates that Leedsichthys was not the direct prey of these crocodiles but more that its body was scavenged by them. Longirostrine metriorhynchids were piscivorous but also opportunistic and may have had more of a scavenging component in their lifestyle than previously understood, as all discovered fossils point in this direction.
... C3 to V6 share a very similar morphology, with short centra and prominent prezygapophyses (Fig 12A, 12B). C4 and C5 preserve the lateral shape of the neural arch, cranially projected in a prominent prezygapophysis, and of the neural spines, caudally projected and distally bifurcated; both features are typical of metriorhynchoid cervical centra [2,99,100]. C5 centrum is missing, represented only by a large imprint (Fig 12A). ...
... C5 centrum is missing, represented only by a large imprint (Fig 12A). V6 is laterally sectioned, with a natural cast of the neural channel preserved below the arch (Fig 12E); the neural spine is short and squarish, consistent with the morphology of metriorhynchoid dorsal centra [99,100]. A small vertebral element lies right below V6 centrum, possibly being its left lateral process. ...
... Therefore, the origin of Metriorhynchidae must be pre-Bathonian. Moreover, our study supports the hypothesis that the taxonomic diversity observed in the Callovian metriorhynchids of western Europe (with members of Metriorhynchinae and Geosaurinae being present, e.g., [2,4,95,99]) was likely the result of the marine transgression at the beginning of the Callovian expanding the geographical range of pre-existing clades, and not the origination of the clades themselves. ...
Despite their extremely rare and fragmentary record, aquatic crocodylomorphs from the Middle to Upper Jurassic (Bajocian-Tithonian) Rosso Ammonitico Veronese (RAV) of northeastern Italy have sparked interest since the late 18th century. Among marine reptiles, Tha-lattosuchia is by far one of the best represented groups from the RAV units, especially in the Middle Jurassic. Although some specimens have been the subject of multiple studies in recent times, most of them still lack precise stratigraphic assignment and taphonomic assessment, while others remain undescribed. Here we provide a comprehensive revision of the thalattosuchian record from the RAV, alongside the most up-to-date age determination , by means of calcareous nannofossils, when available. Three new metriorhynchoid specimens are described for the first time from the Middle Jurassic of Asiago Plateau (Vicenza province). While the taphonomy of the newly described specimens hampers any taxonomic attribution below superfamily/family level, all three were confidently assigned to a precise interval between the upper Bajocian and the upper Bathonian. This revised record has major paleobiogeographical implications: the new specimens confirm an early origin and distribution of Metriorhynchoidea in the Tethys area and suggest a fast colonization of the open-ocean environment since the upper Bajocian. PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.
... Specimens that pertain to this clade are known from the late Oxfordian/early Kimmeridgian to early Tithonian of England, France, Germany, and Switzerland (see Abel, Sachs & Young, 2020;Young et al., 2020b). Tooth crowns of these taxa range from being mediolaterally compressed to almost as robust as Dakosaurus teeth (Lepage et al., 2008;Abel, Sachs & Young, 2020); the 'Passmore crocodile' -OUMNH J1583). The distribution of serrations in this clade is not well understood, but the specimen from Germany described by Abel, Sachs & Young (2020) had irregular microscopic denticles (incipient microziphodonty, Young et al., 2013a), while it is unclear if all the teeth of the 'Passmore crocodile' (OUMNH J1583) have denticles. ...
... The crown MRUM 1315/1 suggests that Thalattosuchus had a broad geographical range across Europe in the early Callovian, spanning from France to Russia, and PIN 5477/3253 suggests that the genus remained in the Middle Russian Sea at least until the middle Callovian. The majority of Thalattosuchus specimens are known from middle-late Callovian deposits of the UK and late Callovian-early Oxfordian deposits of northern France (e.g., Eudes-Deslongchamps, 1867-69;Andrews, 1913;Lepage et al., 2008;. ...
... Our data shows that during the Callovian, at least three or four metriorhynchid species were present in the Middle Russian Sea and that there probably should be some taxonomic overlap with metriorhynchids known from Western Europe (e.g., Eudes-Deslongchamps, 1867-69;Andrews, 1913;Buffetaut, 1982;Lepage et al., 2008;Young et al., 2013a;Foffa et al., 2018a). However, the two early Callovian geosaurin teeth have morphologies not observed in known material from Western Europe. ...
From the Middle Jurassic to the Early Cretaceous, metriorhynchid crocodylomorphs inhabited marine ecosystems across the European archipelago. Unfortunately, European metriorhynchids are only well known from Germany, France, and the UK, with the Eastern European fossil record being especially poor. This hinders our understanding of metriorhynchid biodiversity across these continuous seaways, and our ability to investigate provincialism. Here we describe eleven isolated tooth crowns and six vertebrae referable to Metriorhynchidae from the Callovian, Oxfordian, Volgian (Tithonian), and Ryazanian (Berriasian) or Valanginian of European Russia. We also describe an indeterminate thalattosuchian tooth from the lower Bajocian of the Volgograd Oblast, the first discovery of a marine reptile from the Bajocian strata of European Russia. These rare fossils, along with previous reports of Russian thalattosuchians, indicate that thalattosuchians have been common in the Middle Russian Sea since it was formed. Palaeolatitude calculations for worldwide metriorhynchid-bearing localities demonstrate that the occurrences in European Russia are the most northern, located mainly between 44–50 degrees north. However, metriorhynchids appear to be rare at these palaeolatitudes, and are absent from palaeolatitudes higher than 50°. These observations support the hypothesis that metriorhynchids evolved an elevated metabolism but were not endo-homeothermic, especially as endo-homeothermic marine reptiles (ichthyosaurs and plesiosaurs) remained abundant at much higher palaeolatitudes.
... Overall, the nasals are triangular in shape, with the anterior part being elongate and acute. This shape is found in most metriorhynchoids (Andrews, 1913;Lepage et al., 2008) including rhacheosaurines such as Cricosaurus Wagner, 1858 (Fraas, 1902;Herrera, Fernández & Gasparini, 2013;Parrilla-Bel & Canudo, 2015;Sachs et al., 2019Sachs et al., , 2021, derived geosaurins like Dakosaurus, Plesiosuchus, Torvoneustes, Purranisaurus (Wilkinson, Young & Benton, 2008;Pol & Gasparini, 2009;Young et al., 2012bYoung et al., , 2013b and basal metriorhynchoid such as Pelagosaurus typus Bronn, 1841 (Pierce & Benton, 2006). Based on the skull reconstruction (Fig. 4), the nasals do not reach the premaxillae anteriorly. ...
... 5C, 7). As in most metriorhynchids, the posterolateral corner of the prefrontal is rounded in MJSN BSY008-465 (Andrews, 1913;Lepage et al., 2008), which differs from the geosaurines To. coryphaeus (Young et al., 2013b) and D. maximus (Young et al., 2012a;Pol & Gasparini, 2009) in which the posterolateral corner is angular. The inflection point of this corner is directed posteriorly and forms with the midline of the skull an angle of about 70 , which is found in other Geosaurinae such as To. ...
... This ridge forms the posterior part of the postorbital-squamosal ridge, whose postorbital-squamosal contact would be an area of muscle attachment (Holliday & Witmer, 2007Young et al., 2013b). This ridge is present in all Metriorhynchidae but significantly lower among Metriorhynchinae compared to Geosaurinae (Andrews, 1913;Lepage et al., 2008;Pol & Gasparini, 2009;Young et al., 2012bYoung et al., , 2013bYoung & Andrade, 2009). The median process of the squamosal forms the posterolateral corner of the supratemporal fossa and was probably in contact with the lateral process of the parietal, this contact however is not preserved. ...
Metriorhynchids are marine crocodylomorphs found across Jurassic and Lower Cretaceous deposits of Europe and Central and South America. Despite being one of the oldest fossil families named in paleontology, the phylogenetic relationships within Metriorhynchidae have been subject to many revisions over the past 15 years. Herein, we describe a new metriorhynchid from the Kimmeridgian of Porrentruy, Switzerland. The material consists of a relatively complete, disarticulated skeleton preserving pieces of the skull, including the frontal, prefrontals, right postorbital, nasals, maxillae, right premaxillae and nearly the entire mandible, and many remains of the axial and appendicular skeleton such as cervical, dorsal, and caudal vertebrae, ribs, the left ischium, the right femur, and the right fibula. This new specimen is referred to the new species Torvoneustes jurensis sp. nov. as part of the large-bodied macrophagous tribe Geosaurini. Torvoneustes jurensis presents a unique combination of cranial and dental characters including a smooth cranium, a unique frontal shape, acute ziphodont teeth, an enamel ornamentation made of numerous apicobasal ridges shifting to small ridges forming an anastomosed pattern toward the apex of the crown and an enamel ornamentation touching the carina. The description of this new species allows to take a new look at the currently proposed evolutionary trends within the genus Torvoneustes and provides new information on the evolution of this clade.
... Plusieurs espèces furent rattachées au genre Machimosaurus (Sauvage, 1874 ;Sauvage et Liénard, 1879) sur la base de matériel trouvé dans le Jurassique français. Dans ses travaux, Krebs (1967Krebs ( , 1968) ne retint comme valide que l'espèce type Machimosaurus hugii à laquelle furent également rapportés des spécimens de l'Oxfordien supérieur de la Meuse (Maubeuge 1963(Maubeuge , 1968Hua 1996), du Kimméridgien inférieur de l'Ain (Buffetaut 1982a) et de Normandie (Buffetaut 1982b ;Lepage et al. 2008). Plus tard, l'espèce Machimosaurus mosae Liénard in Sauvage et Liénard, 1879, du Kimméridgien supérieur fut rétablie (Hantzpergue et al. 1982 ;Hua et al., 1993 ;Vignaud, 1995 ;Hua, 1999 ;Pierce et al., 2009 ;Young et al., 2014a ;Brignon, 2023). ...
Intensive exploitation of the Calcaire de Tonnerre in Burgundy, France (Late Oxfordian - Early Kimmeridgian, Planula and Platynota zones), as a building stone was conducive to palaeontological discoveries during the 19th century. The most important collection of fossils from the Calcaire de Tonnerre was built up by Charles Rathier (1812–1888), a lawyer at the court of first instance of Tonnerre, who was briefly mayor of the city and deputy of the French Constituent Assembly between 1848 and 1849. This almost forgotten amateur fossil collector played a major role in the knowledge of the Jurassic fauna of Burgundy. This article traces the history of this collection, which was donated to the École des Mines de Paris by a relative by marriage, Colonel Jules André Jullien (1850–1911). The palaeontological collections of this school were transferred in the 1970s to the Muséum National d’Histoire Naturelle, Paris, and to the Université Claude Bernard Lyon 1. A great part of the vertebrate remains from the Calcaire de Tonnerre in the former Rathier collection has been rediscovered in these two institutions. Together with some scattered specimens from other collections formed in the 19th century, this material reveals the presence of several species of hybodontiform elasmobranchs, pycnodontiforms, ginglymodians, teleosteomorphs, plesiosaurs and crocodylomorphs. -- Résumé -- L’exploitation intensive du Calcaire de Tonnerre (Oxfordien supérieur - Kimméridgien inférieur, zones à Planula et Platynota) comme pierre de construction favorisa les découvertes paléontologiques au XIXe siècle. La plus importante collection de fossiles du Calcaire de Tonnerre avait été constituée par Charles Rathier (1812-1888), avocat-avoué au tribunal de première instance de Tonnerre, qui fut brièvement maire de la ville et député à l’Assemblée constituante entre 1848 et 1849. Ce collectionneur amateur, pratiquement oublié, joua pourtant un rôle prépondérant dans la connaissance des faunes du Jurassique de Bourgogne. Cet article retrace l’histoire de cette collection qui fut offerte à l’École des Mines de Paris par un parent par alliance, le colonel Jules André Jullien (1850–1911). Les collections paléontologiques de cette école furent transférées dans les années 1970 au Muséum National d’Histoire Naturelle, Paris, et à l’Université Claude Bernard Lyon 1. Une grande partie des restes de vertébrés du Calcaire de Tonnerre de l’ancienne collection Rathier a pu être retrouvée dans ces deux institutions. Avec quelques spécimens épars d’autres collections formées au XIXe siècle, ce matériel met en évidence plusieurs espèces d’élasmobranches hybodontiformes, des pycnodontiformes, des ginglymodiens, des téléostéomorphes, des plésiosaures et des crocodylomorphes.
... Plusieurs autres espèces furent ensuite rattachées au genre Machimosaurus (Sauvage 1874 ; Sauvage & Liénard 1879) sur la base de matériel trouvé dans Jurassique français. Dans ses travaux, Krebs (1967Krebs ( , 1968 ne retint comme valide que l'espèce type Machimosaurus hugii à laquelle furent également rapportés des spécimens de l'Oxfordien supérieur de la Meuse (Maubeuge 1963(Maubeuge , 1968Hua 1996), du Kimméridgien inférieur de l'Ain (Buffetaut 1982a) et de Normandie (Buffetaut 1982b ;Lepage et al. 2008). Plus tard, l'espèce Machimosaurus mosae du Kimméridgien supérieur fut rétablie (Hua et al. 1993 ;Hua 1999 ;Vignaud 1995 ;Pierce et al. 2009 ;Young et al. 2014a). ...
... Échelle : 2 cm. Mis à part les Konservat-Lagerstätten de Cerin et Orbagnoux dans l'Ain (Thiollière 1854-1873 ; Lortet 1892 ; Bernier et al. 2014), Canjuers dans le Var (Roman et al. 1994; Peyer et al. 2014), Crayssac dans le Lot (Hantzpergue & Lafaurie 1994; Mazin et al. 1997) et du Causse Méjean en Lozère (Moreau et al. 2022), célèbres pour la conservation exceptionnelle des fossiles qui s'y rencontrent, les carrières à ciment de Fumel et ses environs ont livré un des plus riches assemblages de vertébrés du Jurassique supérieur français à côté des gisements de l'Oxfordien supérieur des environs de Lisieux(Bigot & Brasil 1904 ; Buffetaut et al. 1985), du Kimmeridgien des environs du Havre, Octevillesur-Mer, Villerville et Cricqueboeuf(Lennier 1868(Lennier , 1887(Lennier , 1892Candoni 1995 ;Lepage et al. 2008 ;Lepage 2014), du Kimméridgien supérieur d'Alligny-Cosne dans la Nièvre (Brignon 2020), du Kimméridgien-Tithonien duBoulonnais (Sauvage 1867, 1874, 1880 Hua et al. 1993 ;Cuny et al. 1991 ; Bardet et al. 1997 ; Vadet et al. 1997 ;Brignon 2015), de l'Yonne(Sauvage 1879 ; Priem 1911 ; Gand et al. 2012) et du Tithonien de l'île d'Oléron(Candoni 1995 ;Vullo et al. 2014). Jusqu'alors uniquement connu par un mémoire de Henri-Émile Sauvage publié en 1902, l'ensemble des spécimens de Fumel récoltés durant la seconde moitié du XIXe siècle par Jacques-Ludomir Combes était considéré comme perdu. ...
The vertebrates from the Upper Kimmeridgian of Fumel (Lot-et-Garonne department, France) in the collection of Jacques-Ludomir Combes (1824-1892). --- ABSTRACT --- This article presents the history of the collection of Jacques-Ludomir Combes (1824-1892), a pharmacist living in Fumel, who built up the most important collection of fossils and prehistoric objects from the Lotet-Garonne department of his time. In 1880, Combes sold his collection to the Museum of Agen, where an entire room was devoted to its exhibition. Among the most remarkable specimens were numerous vertebrate remains from the Upper Kimmeridgian of Fumel and its surroundings, whose discoveries were closely linked to the intensive exploitation of the region’s cement quarries. These specimens were studied in the early 1900s by Henri-Émile Sauvage (1842-1917), who published a study on them in 1902. After the museum was restructured and renamed the Musée des Beaux-Arts d’Agen, the natural history collections were relegated to storage. Long considered lost, dispersed, or even destroyed, many Kimmeridgian vertebrates of Fumel from the Combes collection have been rediscovered and are presented here for the first time since the work of Sauvage. This vertebrate assemblage, the richest known today in the Upper Jurassic of southwestern France, highlights a fauna composed of chondrichthyans (Hybodontiformes, Holocephali), actinopterygians (Pycnodontiformes, Ginglymodi, Halecomorphi, Pachycormiformes), turtles (Thalassochelydia), ichthyosaurs (Ophthalmosauridae), plesiosaurs (Cryptoclididae) and thalattosuchians (Teleosauroidea, Metriorhynchoidea).
--- Résumé --- Cet article présente l’histoire de la collection de Jacques-Ludomir Combes (1824-1892), pharmacien à Fumel, qui avait formé en son temps la plus importante collection de fossiles et d’objets préhistoriques du Lot-et-Garonne. Combes vendit en 1880 sa collection au Musée d’Agen dans lequel une salle entière lui était consacrée. Parmi les spécimens les plus remarquables, se trouvaient de nombreux restes de vertébrés du Kimméridgien supérieur de Fumel et ses environs, dont la découverte était étroitement liée à l’exploitation intensive des carrières à ciment de la région. Ces spécimens furent étudiés au début des années 1900 par Henri-Émile Sauvage (1842-1917) qui leur consacra un mémoire publié en 1902. Après une restructuration du musée qui prit le nom de Musée des Beaux-Arts d’Agen, les collections d’histoire naturelle furent reléguées dans des réserves. Longtemps considérés comme perdus, dispersés, voire détruits, de nombreux spécimens de vertébrés du Kimméridgien de Fumel de la collection Combes ont été redécouverts et sont présentés ici pour la première fois depuis les travaux de Sauvage. Cet ensemble de vertébrés, le plus riche aujourd’hui connu dans le Jurassique supérieur du sud-ouest de la France, met en évidence une faune composée de chondrichtyens (Hybodontiformes, Holocephali), d’actinoptérygiens (Pycnodontiformes, Ginglymodi, Halecomorphi, Pachycormiformes), de tortues (Thalassochelydia), d’ichtyosaures (Ophthalmosauridae), de plésiosaures (Cryptoclididae) et de thalattosuchiens (Teleosauroidea, Metriorhynchoidea).
... Although similar notches are present in other pholidosaurids (e.g. Mook 19344;Sereno et al. 2001;Lepage et al. 2008;Fortier et al. 2011), the position of this opening that splits the premaxillary tooth series into distinct units is considered autapomorphic of Elosuchus (Young et al. 2016). ...
... P5 is located posteromedially relative to the P4 alveolus, as in Elosuchus (de Lapparent de Broin 2002;Fortier et al. 2011;Young et al. 2016), and Chalawan thailandicus (Martin et al. 2013), while P5 is posterolateral to the P4 alveoli in most pholidosaurids (e.g. Mook 1934;Sereno et al. 2001;Wu et al. 2001;Hua et al. 2007;Lepage et al. 2008;Fortier et al. 2011). The posterolateral position of the fifth premaxillary tooth regarding the tooth row was proposed as a synapomorphy of Pholidosauridae by Fortier et al. (2011), but the medial 'migration' of the last premaxillary alveolus could be characteristic of a more inclusive clade within pholidosaurids (Young et al. 2016). ...
Sometimes Natural History Museums unknowingly treasure singular specimens in their collections for decades. The re-discovery of such elements allows the description of previously unknown features of well-known taxa. Here, we describe a nearly complete left premaxilla attributed to the pholidosaurid Elosuchus. Specimen IPS3303 shows some remarkable differences with previously known premaxillae of Elosuchus, especially concerning the relative position of the fifth premaxillary tooth and the premaxilla-maxilla sutural surface morphology. Because of the scarcity of current data, it is difficult to evaluate the significance of such differences. The described element is about 40% larger than the largest premaxilla of Elosuchus known so far, suggesting that this taxon could achieve remarkable body size proportions. The preliminary analyses of the dentition and the neurovascular system of the premaxilla provide new insight into the palaeoecology of this riverine crocodylomorph from the Cretaceous of Africa.
... The presence of Metriorhynchidae in the Jurassic of Normandy has been known since the 19th century, (Cuvier, 1808(Cuvier, , 1824Blainville, 1853;Eudes-Deslongchamps, 1867-1869, leading to the erection of several species within this family, Metriorhynchus superciliosus Blainville, 1853, Metriorhynchus brachyrhynchus Eudes-Deslongchamps, 1868, Metriorhynchus blainvillei Eudes-Deslongchamps, 1869, Metriorhynchus moreli Eudes-Deslongchamps, 1867-1869 and Metriorhynchus hastifer Eudes-Delongschamps, 1868 (see Young et al., 2010Young et al., , 2020 for taxonomic changes). Most of the studied metriorhynchid remains from Normandy consist of skull specimens and despite their recognized local high diversity during the Jurassic (Eudes-Deslongchamps, 1867-1869Wenz, 1968Wenz, , 1970Lepage et al., 2008;Hua, 2019), knowledge about their postcranial anatomy is limited (Hua, 2003;Lepage et al., 2008). The study of a wellpreserved specimen (MPV 2010.3.610) from the Vaches-Noires cliffs extends our knowledge of this group. ...
... The presence of Metriorhynchidae in the Jurassic of Normandy has been known since the 19th century, (Cuvier, 1808(Cuvier, , 1824Blainville, 1853;Eudes-Deslongchamps, 1867-1869, leading to the erection of several species within this family, Metriorhynchus superciliosus Blainville, 1853, Metriorhynchus brachyrhynchus Eudes-Deslongchamps, 1868, Metriorhynchus blainvillei Eudes-Deslongchamps, 1869, Metriorhynchus moreli Eudes-Deslongchamps, 1867-1869 and Metriorhynchus hastifer Eudes-Delongschamps, 1868 (see Young et al., 2010Young et al., , 2020 for taxonomic changes). Most of the studied metriorhynchid remains from Normandy consist of skull specimens and despite their recognized local high diversity during the Jurassic (Eudes-Deslongchamps, 1867-1869Wenz, 1968Wenz, , 1970Lepage et al., 2008;Hua, 2019), knowledge about their postcranial anatomy is limited (Hua, 2003;Lepage et al., 2008). The study of a wellpreserved specimen (MPV 2010.3.610) from the Vaches-Noires cliffs extends our knowledge of this group. ...
... The depositional environment is still calm but the sedimentation rate increases compared with the summit of the "Marnes de Dives" (The Lamberti Zone is 5 metres thick and the Mariae Zone is 20 metres thick) (Dugué et al., 1998). Fossils are scarcer in this level but remains of Thalattosuchia have already been found (Lepage et al., 2008;Hua, 2013). It is possible that the specimen comes from the upper Callovian, as the individual is relatively well-preserved and the "Marnes de Dives" that crop out on the foreshore have produced abundant vertebrate material. ...
The metriorhynchids from the Jurassic of Normandy have been known since the 19th century. However, the remains studied until now have rarely been found in anatomical connection. The acquisition of specimen MPV 2010.3.610 that was found in the Callovian of Vaches-Noires cliffs by the Paleospace Museum in 2010, allowed the first description of the most complete Metriorhynchidae from this locality so far. The analysis of this Metriorhynchidae raises questions about the taxonomic value of several criteria currently used to distinguish between the different Callovian and Oxfordian species. The study of the cranial and postcranial elements shows that this specimen presents diagnostic criteria of different Metriorhynchidae such as the shape of the prefrontals, the mandible, the palato-maxillary suture, the atlas/axis, the cervical vertebrae as well as the extension of the jugal bone and the morphology of the teeth. A discussion highlights the limitations of the current classification of Metriorhynchidae.
... 1). Metriorhynchidae evolved during the Middle Jurassic, and diversified throughout the Jurassic into highly successful marine predators, becoming extinct during the Early Cretaceous (Fraas, 1902;Andrews, 1913;Lepage et al., 2008;Pol and Gasparini, 2009;Young et al., 2010;Larsson et al., 2011;Chiarenza et al., 2015;Herrera and Vennari, 2015;Fernández et al., 2019;Sachs et al., 2020). As they transitioned from semiaquatic basal metriorhynchoids into open-ocean swimming metriorhynchids, their body plan underwent a radical change, evolving paddle-shaped limbs, a hypocercal tail fin, and hypertrophied nasal salt glands, while losing their osteoderms (Fraas, 1902;Andrews, 1913;Fernández and Gasparini, 2008;Young et al., 2010;Wilberg, 2015;Ősi et al., 2018). ...
... These characters match those seen in the English 'M.' brachyrhynchus specimens (NHMUK PV R 3699, NHMUK PV R 3700, NHMUK PV R 3804; Andrews, 1913). The distinctly concave supraoccipital is a readily identifiable character, and it is not seen in the Vaches Noires specimens of Thalattosuchus superciliosus or Suchodus durobrivensis (see Lepage et al., 2008). Nor is this feature seen in Maledictosuchus riclaensis (Parrilla-Bel et al., 2013), Dakosaurus andiniensis (Pol and Gasparini, 2009), D. cf. ...
... In essence, there is a gap between the two otoccipital corners, which is filled by the basioccipital. This is the case in most other thalattosuchians (Andrews, 1913;Pierce and Benton, 2006;Lepage et al., 2008;Jouve, 2009;Foffa and Young, 2014). In derived geosaurine metriorhynchids such as Plesiosuchus manselii (Young et al., 2012) and Torvoneustes coryphaeus , however, the otoccipital covers the entire dorsal margin of the occipital condyle, the left and right otoccipitals meet to exclude the basioccipital from the dorsal margin of the condyle, and thus the floor of the foramen magnum. ...
During their long evolutionary history crocodylomorphs achieved a great diversity of body sizes, ecomorphotypes and inferred feeding ecologies. One unique group of crocodylomorphs are the thalattosuchians, which lived during the Jurassic and Cretaceous (ca. 191–125 Ma). They transitioned from shallow marine species, like teleosauroids, into fully pelagic forms with paddle shaped limbs and a vertically orientated tail fluke, the metriorhynchids. The osteological adaptations that allowed metriorhynchids to live in the water are generally well understood, but less is known about their neurosensory and endocranial systems, such as the brain, inner ears, sinuses and cranial nerves and how they relate to their aquatic lifestyle. Based on micro-computed tomography (μCT) data and three-dimensional models, we here describe the braincase and endocranial anatomy of a fully marine metriorhynchid, ‘Metriorhynchus’ cf. ‘M.’ brachyrhynchus (NHMUK PV OR 32617). We found several neuroanatomical features that likely helped this species function in its marine environment. These include a unique flexure in the brain endocast not seen in other thalattosuchians. Other features that have previously been seen in thalattosuchians include enlarged cerebral hemispheres, a hypertrophied venous sinus system, enlarged internal carotid arteries and foramina, and closed/absent lateral pharyngotympanic foramina. The specimen also possesses a pelagic metriorhynchid bony labyrinth morphology, with a compact and dorsoventrally short shape, thick semicircular canals, an enlarged vestibule and potentially a short cochlear duct. A review of character distribution confirms that some of these features evolved at the base of Thalattosuchia in semiaquatic species, long before metriorhynchids became pelagic, suggesting that endocranial anatomy helped allow metriorhynchoids colonize the ocean realm.
